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Midori Tuda Last modified date:2024.05.18

Professor / Agricultural Bioresource Sciences
Department of Bioresource Sciences
Faculty of Agriculture

Graduate School
Other Organization

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Research themes, collaboration, and publications .
Academic Degree
Country of degree conferring institution (Overseas)
Field of Specialization
Population ecology, Evolutionary ecology
Total Priod of education and research career in the foreign country
Outline Activities
Prey-predator or host-parasitoid population dynamics, evolutionary ecology and speciation, using both laboratory experimental systems and agricultural ecosystems. Effect of global environmental changes such as global warming and atmospheric CO2 rise on predation/parasitization/infection systems. Spatial population dynamics. Chaotic population dynamics. Preadaptation. Host-plant shift as a possible cause of speciation in herbivores. Anthropogenic, host-plant use, or geographic effects on genetic population structure of pests. Nanoparticles on pests and plants (including volatile emissions). Population structure, Wolbachia infection, and evolutionary dynamics of invasive pests of leguminous plants. Image-based machine learning of insect species and gender.
Research Interests
  • Insect pest control with nanopesticides
    keyword : Nanotechnology, herbivore induced plant volatiles, nanosilica
  • Gender and species classification of insects in random position by machine learning
    keyword : Artificial intelligence, deep learning
  • Ecological factors and gene expression of host-shifting insects
    keyword : host plant, herbivorous insect, phytophagous insect, host jump, RNA-seq
  • Evolutionary mechanism of intrapopulation polymorphism
    keyword : antenna, sexual conflict
  • Effect of genetic diversity on the persistence of plant-herbivore-parasitoid systems
    keyword : genetic diversity, species diversity
    1995.04Effect of genetic diversity on persistence of host-parasitoid systems.
  • Effect of global warming and CO2 increase on host-parasitoid systems
    keyword : temperature, plant reproductive dynamics, host-parasitoid, predator-prey
    1991.04Effect of global warming on plant-host-parasitoid and plant-predator-prey systems.
  • Factors determining the diversity of bean-bean beetles-parasitoid systems
    keyword : number of species, evolution, plant-herbivore, host-parasitoid
    1995.01Factors determining species diversity of legume-bruchid-parasitoid systems.
  • Effect of genetic diversity and host plants on pests and their natural enemy populations
    keyword : geographic population, molecular marker, human-aided dispersal
    1995.04Genetic diversity and ecological property (host plants, habitat) in pest and natural enemy populations.
  • Detection of nonlinear mechanism from population dynamics data
    keyword : chaos, transient, density dependence, statistical method
    1995.01Detection of nonlinear mechanisms from population dynamics data.
Current and Past Project
  • See Activity
Academic Activities
1. Gao S, Tuda M, Silica and selenium nanoparticles attract or repel scale insects by altering physicochemical leaf traits, Plants, 13, 952, 2024.03, [URL], Although nanoparticles have gained attention as efficient alternatives to conventional agricultural chemicals, there is limited knowledge regarding their effects on herbivorous insect behavior and plant physicochemistry. Here, we investigated the effects of foliar applications of nano-silica (SiO2NPs) and nano-selenium (SeNPs), and bulk-size silica (SiO2) on the choice behavior of the arrowhead scale insect on mandarin orange plants. One leaf of a bifoliate pair was treated with one of the three chemicals, while the other was treated with water (control). The respective SiO2, SeO2, calcium (Ca), and carbon (C) content levels in the leaf epidermis and mesophyll were quantified using SEM–EDX (or SEM–EDS); leaf toughness and the arrowhead scale density and body size were measured. First-instar nymphs preferred silica-treated leaves and avoided SeNP-treated leaves. SiO2 content did not differ between control and SiO2NP-treated leaves, but was higher in bulk-size SiO2-treated leaves. The SiO2 level in the control leaves was higher in the SiO2NP treatment compared with that in the control leaves in the bulk-size SiO2 treatment. Silica-treated leaves increased in toughness, but SeNP-treated leaves did not; leaf toughness increased with mesophyllic SiO2 content. The insect density per leaf increased with leaf toughness, SiO2 content and, in the SiO2NP treatment, with epidermal C content. There was no correlation between SeO2 content and insect density. This study highlights the potential uses of SeNPs as an insect deterrent and of silica for enhancing leaf toughness and attracting scale insects..
2. Miksanek JR, Adarkwah C, Tuda M, Low concentrations of selenium nanoparticles enhance the performance of a generalist parasitoid and its host, with no net effect on host suppression, Pest Management Science, doi: 10.1002/ps.7907, 80, 1812–1820, 2024.03, Background: The environmental and economic costs of conventional insecticides have stirred an interest in alternative management tactics, including the use of nanotechnologies. Selenium nanoparticles (SeNPs) have many applications in agriculture but may not be compatible with biological control; however, low concentrations of SeNPs may benefit natural enemies via hormesis. This study investigates the concentration-dependent effects of SeNPs (0-1000 mg L-1 ) on Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae), a generalist parasitoid of stored product pests.
Results: The LC50 of SeNPs was 1540 mg L-1 for female parasitoids and 1164 mg L-1 for males. SeNPs had a significant hormetic effect; average lifespan increased by 10% at a concentration of 4.03 mg L-1 for females and by 35% at 13.83 mg L-1 for males. In a bioassay including hosts [the azuki bean beetle, Callosobruchus chinensis (L.) (Coleoptera: Chrysomelidae: Bruchinae)], a low concentration of SeNPs (25 mg L-1) enhanced the performance of female parasitoids; lifespan increased by 23% and the number of offspring increased by 88%. However, the number of emerging hosts did not significantly decrease; in the absence of parasitism, SeNPs actually improved host emergence by 17%.
Conclusion: Because higher concentrations of SeNPs reduced parasitoid lifespan, whereas low concentrations enhanced not only parasitoid performance but also host emergence, practitioners should exercise caution when considering SeNPs for use in integrated pest management..
3. San PP, Zhang YZ, Helmy EAM, Adarkwah C, Tuda M, Sex-dependent effects of biosynthesized nanoparticles on stored bean pests and their non-target parasitoid, Crop Protection, 173, 106352, 2023.07, The efficacy of green nanotechnology in biological control remains uncertain because of a lack of knowledge of side-effects on natural enemies and sex-dependent effects on target and non-target organisms. To address this issue, we exposed stored bean pest beetles, Callosobruchus chinensis and C. maculatus (Chrysomelidae: Bruchinae), the former infected by endosymbiont Wolbachia, and their non-target parasitoid wasp Anisopteromalus calandrae (Pteromalidae) to six types of fungus-synthesized nanoparticles (NPs): silver (AgNPs), selenium (SeNPs), silicon dioxide (SiO2NPs), copper oxide (CuONPs), titanium dioxide (TiO2NPs) and zinc oxide (ZnONPs). The nanoparticles were applied directly to the adults or indirectly via azuki beans, which served as the oviposition medium for female beetles and the sole resource for beetle larvae.

Susceptibility to the nanoparticles varied across species and between sexes. SeNPs decreased the longevity of female A. calandrae, while both SeNPs and AgNPs decreased the longevity of female C. maculatus. Surprisingly, ZnONPs increased the adult longevity of C. chinensis, and SeNPs extended the longevity of male C. maculatus. When the bean surface was treated, SeNPs significantly reduced the fecundity and egg hatchability of C. maculatus, resulting in 35% reduction in emerged adults, while SiO2NPs reduced egg hatchability in both beetle species. Interestingly, none of the nanoparticles negatively impacted C. chinensis adults, likely due to the high abundance of the endosymbiont Wolbachia at this life stage. Overall, our results suggest that biosynthesized SeNPs have potential as an effective alternative insecticide for controlling C. maculatus in storage. However, the nanoparticles can increase the fitness of Wolbachia-infected pests, and also affect biocontrol agents like A. calandrae..
4. Iwase S, Tuda M, Sugawara Y, Fukuda K, Miksanek JR, Watanabe M, Negative phototaxis of jumping cocooned parasitoid wasp larvae against short wavelengths and physicochemical properties of the cocoon shell, Scientific Reports, 13, 9562, 2023.06, [URL], The parasitoid wasp Bathyplectes anurus (Hymenoptera: Ichneumonidae: Campopleginae) is a successful biocontrol agent against the alfalfa weevil, Hypera postica. This weevil is a serious pest of beneficial fabaceous plants such as alfalfa and Chinese milk vetch. One of the possible reasons for the success of this wasp in hot climates may be the ability of its cocooned larvae to repeatedly jump and roll until they relocate themselves away from detrimental sunlight and heat. It is not yet known which wavelengths of light trigger this avoidance behavior or the microstructure of the cocoon shell that might allow light transmission. Here, the response of the cocooned larvae to different wavelengths, and the microstructure, hardness, and elemental components of the cocoon shell were studied. A population of cocooned larvae were introduced on the boundary line between illuminated and shaded areas with blue, green, red, or near-infrared light-emitting diodes. The cocoons moved away from the blue and green light. The distance from the boundary to the cocoons in the shaded area was longer under these long wavelengths, followed by the red light and shortest under the near-infrared light and nil under darkness. No difference was found in mortality between different wavelengths after three days of illumination. Scanning electron microscope observations of the surface of the cocoon shell revealed that the belt-like central ridge was porous, which likely allows ventilation and light transmission. The surface of the cocoon shell showed a uniform distribution of sulfur, potentially aiding in the capture of green wavelengths. The ridge had twice the thickness of the main body and was 1.9 times harder than the main body. These results may be applied to better understand the individual responses of this biological control agent to modifications to their environment, including light pollution..
5. Helmy EAM, San PP, Zhang YZ, Adarkwah C, Tuda M, Entomotoxic efficacy of fungus-synthesized nanoparticles against immature stages of stored bean pests, Scientific Reports, 10.1038/s41598-023-35697-1, 13, 8508, 2023.05, [URL].
6. Miksanek JR, Tuda M, Endosymbiont-mediated resistance to entomotoxic nanoparticles and sex-specific responses in a seed beetle, Journal of Pest Science, 96, 1257-1270, 2023.06, [URL], Bacterial symbionts can promote insecticide resistance in their hosts by isolating and degrading insecticidal compounds or altering the expression of host genes. Although Wolbachia, a common endosymbiont in arthropods, typically does not influence insecticide resistance, there are cases of increased or decreased susceptibility. Due to the restrictions of applying conventional insecticides in a stored product setting, studies on alternative control methods are needed, including those on entomotoxic nanoparticles and the potential for resistance. For pests of stored beans, selenium nanoparticles (SeNPs) are relatively innocuous to the azuki bean beetle, Callosobruchus chinensis (L.) (Coleoptera: Chrysomelidae: Bruchinae). Here, we hypothesized that this response is mediated by Wolbachia, and we tested this using an isofemale line of C. chinensis (infected or uninfected with Wolbachia). Our results showed that the lifespan of Wolbachia-infected females was not affected by SeNPs, but increasing concentrations of SeNPs still had a negative effect on fecundity; in uninfected females, increasing concentrations of SeNPs significantly decreased both lifespan and fecundity. However, in males, SeNPs enhanced lifespan and decreased the incidence of sexual harassment behavior regardless of infection status (for uninfected males, the duration of harassment behavior also decreased). In the presence of males, 72-h female reproduction increased independent of infection status or SeNP treatment, but egg hatchability was reduced by male presence and SeNPs. This study documents a valuable example of symbiont-mediated resistance to entomotoxic nanoparticles..
7. Zhang YZ, Jin Z, Miksanek JR, Tuda M, Impact of a nonnative parasitoid species on intraspecific interference and offspring sex ratio, Scientific Reports,, 11, 23215, 2021.12.
8. Thabet AF, Boraei HA, Galal OA, El-Samahy MFM, Mousa KM, Zhang YZ, Tuda M, Helmy EA, Wen J, Nozaki T, Silica nanoparticles as pesticide against insects of different feeding types and their non-target attraction of predators., Scientific Reports,, 11, 14484, 2021.07, The agricultural use of silica (SiO2) nanoparticles (NPs) has the potential to control insect pests while the safety and tritrophic effects on plants and beneficial natural enemies remains unknown. Here, we evaluate the effects of silica NPs on insect pests with different feeding niches, natural enemies, and a plant. Silica NPs were applied at different concentrations (75–425 mg/L) on field-cultivated faba bean and soybean for two growing seasons. The faba bean pests, the cowpea aphid Aphis craccivora and the American serpentine leafminer Liriomyza trifolii, and the soybean pest, the cotton leafworm Spodoptera littoralis, were monitored along with their associated predators. Additional laboratory experiments were performed to test the effects of silica NPs on the growth of faba bean seedlings and to determine whether the rove beetle Paederus fuscipes is attracted to cotton leafworm-infested soybean treated with silica NPs. In the field experiments, silica NPs reduced the populations of all three insect pests and their associated predators, including rove beetles, as the concentration of silica NPs increased. In soybean fields, however, the total number of predators initially increased after applying the lowest concentration. An olfactometer-based choice test found that rove beetles were more likely to move towards an herbivore-infested plant treated with silica NPs than to a water-treated control, suggesting that silica NPs enhance the attraction of natural enemies via herbivore-induced plant volatiles. In the laboratory, while silica NPs inhibited the development of faba bean roots at 400 mg/L, they did not affect germination and shoot length..
9. Tuda M, Iwase S, Kebe K, Haran J, Skuhrovec J, Sanaei E, Tsuji N, Podlussany A, Merkl O, El-Heneidy AH, Morimoto K, Diversification, selective sweep, and body size in the invasive Palearctic alfalfa weevil infected with Wolbachia, Scientific Reports,, 11, 9664, 2021.05, The alfalfa weevil Hypera postica, native to the Western Palearctic, is an invasive legume pest with two divergent mitochondrial clades in its invading regions, the Western clade and the Eastern/Egyptian clade. However, knowledge regarding the native populations is limited. The Western clade is infected with the endosymbiotic bacteria Wolbachia that cause cytoplasmic incompatibility in host weevils. Our aim was to elucidate the spatial genetic structure of this insect and the effect of Wolbachia on its population diversity. We analyzed two mitochondrial and two nuclear genes of the weevil from its native ranges. The Western clade was distributed in western/central Europe, whereas the Eastern/Egyptian clade was distributed from the Mediterranean basin to central Asia. Intermediate mitotypes were found from the Balkans to central Asia. Most Western clade individuals in western Europe were infected with an identical Wolbachia strain. Mitochondrial genetic diversity of the infected individuals was minimal. The infected clades demonstrated a higher nonsynonymous/synonymous substitution rate ratio than the uninfected clades, suggesting a higher fixation of nonsynonymous mutations due to a selective sweep by Wolbachia. Trans-Mediterranean and within-European dispersal routes were supported. We suggest that the ancestral populations diversified by geographic isolation due to glaciations and that the diversity was reduced in the west by a recent Wolbachia-driven sweep(s). The intermediate clade exhibited a body size and host plant that differed from the other clades. Pros and cons of the possible use of infected-clade males to control uninfected populations are discussed..
10. San PP, Tuda M, Takagi M, Impact of relative humidity and water availability on the life history of the predatory mite Amblyseius swirskii, BioControl,, 66, 497–510, 2021.08.
11. Tuda M, Luna-Maldonado AI,, Image-based insect species and gender classification by trained supervised machine learning algorithms., Ecological Informatics, 60, 101135, 2020.11, Classification of specimens is the important first step to characterize populations and species assemblages. Although species-level classification has been a popular goal, the sex difference and sex ratio are also an important property in ecology and pest control. Here we focus on the images of mixed sex specimens of a stored product pest beetle (Callosobruchus chinensis) and its parasitoids (parasitic wasps; Anisopteromalus and Heterospilus) in various postures and classify them into species and sex, by training supervised machine learning programs: logistic model trees (LMT), random forest, support vector machine (SVM), simple logistic regression, multilayer perceptron and AdaBoost (adaptive boosting). Both object-based features and pixel-based features were extracted from each image. Simple logistic regression, LMT and AdaBoost (employing simple logistic regression as base learner) performed well to classify sexes or species/sexes; average true positive rates (prediction accuracy) of 88.5–98.5% were achieved for within-species sexing of beetles or wasps, 97.3% for two species sexing and 93.3% for three species sexing. For most datasets, the best performed models incorporated both object-based features and pixel-based features. LMT models were identical to simple logistic regression models in most cases. Robust performance and small variation in prediction accuracy of simple logistic regression, irrespective of classification target (sexes or species), was shown, and this is probably because of the efficient feature selection implemented in the algorithm. This study is one of the earliest to classify the gender of insects using machine learning based on still images..
12. Nakamichi Y, Tuda M, Wajnberg E., Intraspecific interference between native parasitoids modified by a non-native parasitoid and its consequence on population dynamics, Ecological Entomology, DOI: 10.1111/een.12909, 45, 2020.12.
13. Sanaei E, Husemann M, Seiedy M, Rethwisch M, Tuda M, Toshova TB, Kim MJ, Atanasova D, Kim I, Global genetic diversity, lineage distribution and Wolbachia infection of the alfalfa weevil Hypera postica (Coleoptera: Curculionidae), Ecology and Evolution, 10.1002/ece3.5474, 9, 9546-9563, 2019.09.
14. Takano S, Tuda M, Takasu K, Furuya N, Imamura Y, Kim S, Tashiro K, Iiyama K, Tavares M, Amaral AC, Unique clade of alphaproteobacterial endosymbionts induces complete cytoplasmic incompatibility in the coconut beetle., Proceedings of the National Academy of Sciences of the United States of America (PNAS), 10.1073/pnas.1618094114, 114(23), 6110–6115, 2017.06, Maternally inherited bacterial endosymbionts in arthropods manipulate host reproduction to increase the fitness of infected females. Cytoplasmic incompatibility (CI) is one such manipulation, in which uninfected females produce few or no offspring when they mate with infected males. To date, two bacterial endosymbionts, Wolbachia and Cardinium, have been reported as CI inducers. Only Wolbachia induces complete CI, which causes 100% offspring mortality in incompatible crosses. Here we report a third CI inducer that belongs to a unique clade of Alphaproteobacteria detected within the coconut beetle, Brontispa longissima. This beetle comprises two cryptic species, the Asian clade and the Pacific clade, which show incompatibility in hybrid crosses. Different bacterial endosymbionts, a unique clade of Alphaproteobacteria in the Pacific clade and Wolbachia in the Asian clade, induced bidirectional CI between hosts. The former induced complete CI (100% mortality), whereas the latter induced partial CI (70% mortality). Illumina MiSeq sequencing and denaturing gradient gel electrophoresis patterns showed that the predominant bacterium detected in the Pacific clade of B. longissima was this unique clade of Alphaproteobacteria alone, indicating that this endosymbiont was responsible for the complete CI. Sex distortion did not occur in any of the tested crosses.
The 1,160 bp of 16S rRNA gene sequence obtained for this endosymbiont had only 89.3% identity with that of Wolbachia, indicating that it can be recognized as a distinct species. We discuss the potential use of this bacterium as a biological control agent..
15. Kébé K, Alvarez N, Tuda M, Arnqvist G, Fox CW, Sembène M, Espíndola A, Global phylogeography of the insect pest Callosobruchus maculatus (Coleoptera: Bruchinae) relates to the history of its main host, Vigna unguiculata., Journal of Biogeography 44, 2515–2526, in press, 2017.11, Aim: The seed beetle Callosobruchus maculatus is an important tropical and subtropical pest of legumes distributed world-wide. Archaeological evidence suggests an African origin with later world-wide invasion facilitated by the last centuries’ legume trading and exchange. To date, no studies could identify the routes or timing of dispersal of the species. Here, we investigate the global phylogeography of this pest to shed light on the main inter-continental dispersal routes that led to it becoming a cosmopolitan pest.
Location: World-wide.
Methods: We sampled seed beetles over a large fraction of the species’ range and sequenced one nuclear and three mitochondrial loci. Using this data, we estimated spatio-temporal phylogeographical reconstructions, and the demographic history of the species. We also used our dataset to evaluate the effect of panmixia on Bayesian demographic estimations.
Results: Callosobruchus maculatus exhibited regional and continental genetic structure, with the highest genetic diversity found in Africa. Our discrete Bayesian phylogeographical approach indicated that the species first dispersed to Asia and then colonized the pantropical belt. The three methods used for inferring the demographic history of C. maculatus indicated a recent demographic expansion in the world-wide dataset, as well as in the subset restricted to African samples. Such a signal was, however, not observed in the subset composed of Asian specimens. This demographic expansion occurred in the Holocene and is likely explained by the spread of cowpea and other host legumes across and out of Africa.
Main conclusions: The inferred dispersal routes support the idea that the evolutionary history of C. maculatus relates to the trade of its main host plant, Vigna unguiculata. Human-mediated processes appear to have shaped the global genetic structure of this pest. As a methodological implication, we demonstrate that coalescent-based demographic reconstructions can be erroneous if the dataset violates the assumption of panmixia..
16. Fukuda K, Yanagawa A, Tuda M, Sakurai G, Kamitani S, Furuya N, Sexual difference in antennal sensilla abundance, density and size in Callosobruchus rhodesianus (Coleoptera: Chrysomelidae: Bruchinae)., Applied Entomology and Zoology, 10.1007/s13355-016-0441-4, 51, 4, 641-651, 2016.11.
17. Saeki Y, Tani S, Fukuda K, Iwase S, Sugawara Y, Tuda M, Takagi M, Costs and benefits of larval jumping behaviour of Bathyplectes anurus., The Science of Nature, 10.1007/s00114-015-1324-1, 103, 1, 2016.02, Bathyplectes anurus, a parasitoid of the alfalfa weevils, forms a cocoon in the late larval stage and exhibits jumping behaviour. Adaptive significance and costs of the cocoon jumping have not been thoroughly studied. We hypothesised that jumping has the fitness benefits of enabling habitat selection by avoiding unfavourable environments. We conducted laboratory experiments, which demonstrated that jumping frequencies increased in the presence of light, with greater magnitudes of temperature increase and at lower relative humidity. In addition, when B. anurus individuals were allowed to freely jump in an arena with a light gradient, more cocoons were found in the shady area, suggesting microhabitat selection. In a field experiment, mortality of cocoons placed in the sun was significantly higher than for cocoons placed in the shade. B. anurus cocoons respond to environmental stress by jumping, resulting in habitat selection. In the presence of potential predators (ants), jumping frequencies were higher than in the control (no ant) arenas, though jumping frequencies decreased after direct contact with the predators. Body mass of B. anurus cocoons induced to jumpsignificantly decreased over time than cocoons that did not jump, suggesting a cost to jumping. We discuss the benefits and costs of jumping behaviour and potential evolutionary advantages of this peculiar trait, which is present in a limited number of species..
18. Iwase S, Tani S, Saeki Y, Tuda M, Haran J, Skuhrovec J, Takagi M, Dynamics of infection with Wolbachia in Hypera postica (Coleoptera: Curculionidae) during invasion and establishment., Biological Invasions, 17, 12, 3639-3648, 2015.12, The process of loss or gain of parasites during invasion of new lands is not well understood. The alfalfa weevil Hypera postica is an invasive pest of various leguminous crops and consists of three major mitochondrial haplotypes, ‘Western’, ‘Egyptian’ and ‘Eastern’. The Western strain is infected with the endosymbiotic proteobacteria Wolbachia, that cause unidirectional complete reproductive incompatibility, in its native (Europe) and an introduced (the United States) ranges. However, our preliminary screening of a few introduced populations in Northern Kyushu, southwestern Japan, failed to detect Wolbachia from the Western strain. A larger-scale and historical assessment of Wolbachia infection may allow to estimate when and how the bacteria were lost, and current geographical distribution of infection among host haplotypes. In this study, we aim to assess the Wolbachia-infection status of H. postica populations throughout Northern Kyushu, where H. postica invasion to Japan was first found. A total of 228 individuals from seven regions in Northern Kyushu collected in different time periods from 1982 to 2015 and 14 individuals from Europe were subjected to PCR diagnostics for Wolbachia. Wolbachia from the Western strain was not detected, irrespective of the time periods and geographic areas in Northern Kyushu. We found ‘Egyptian’-strain H. postica collected most recently from an island off Kyushu harboured a supergroup-B Wolbachia variant. This variant was genetically different from the European Wolbachia variant infecting Western-strain H. postica. The infection was new to the Egyptian haplotype and was estimated to have taken place independently of the loss in the Western strain..
19. Downey MH, Searle R, Bellur S, Geiger A, Maitner BS, Ohm JR, Tuda M, Miller TEX, A comparative approach to testing hypotheses for the evolution of sex-biased dispersal in bean beetles, Ecology and Evolution, 5, 21, 4819-4828, 2015.11.
20. Arnqvist G, Sayadi A, Immonen E, Hotzy C, Rankin D, Tuda M, Hjelmen CE, Johnston JS, Genome size correlates with reproductive fitness in seed beetles., Proceedings of the Royal Society B, 282 (1815), 20151421, 2015.09, The ultimate cause of genome size (GS) evolution in eukaryotes remains a major and unresolved puzzle in evolutionary biology. Large-scale comparative studies have failed to find consistent correlations between GS and organismal properties, resulting in the ‘C-value paradox’. Current hypotheses for the evolution of GS are based either on the balance between mutational events and drift or on natural selection acting upon standing genetic variation in GS. It is, however, currently very difficult to evaluate the role of selection because within-species studies that relate variation in lifehistory traits to variation in GS are very rare. Here, we report phylogenetic comparative analyses of GS evolution in seed beetles at two distinct taxonomic scales, which combines replicated estimation of GS with experimental assays of life-history traits and reproductive fitness. GS showed rapid and bidirectional evolution across species, but did not show correlated evolution with any of several indices of the relative importance of genetic drift. Within a single species, GS varied by 4–5% across populations and showed positive correlated evolution with independent estimates of male and female reproductive fitness. Collectively, the phylogenetic pattern of GS diversification across and within species in conjunction with the pattern of correlated evolution between GS and fitness provide novel support for the tenet that natural selection plays a key role in shaping GS evolution..
21. Kergoat GJ, Le Ru BP, Sadeghi SE, Tuda M, Reid CAM, György Z, Genson G, Ribeiro-Costa CS, Delobel A, Evolution of Spermophagus seed beetles (Coleoptera, Bruchinae, Amblycerini) indicates both synchronous and delayed colonizations of host plants., Molecular Phylogenetics and Evolution, 89, 91-103, 2015.08.
22. Iwase S, Nakahira K, Tuda M, Kagoshima K, Takagi M, Host-plant dependent population genetics of the invading weevil Hypera postica, Bulletin of Entomological Research, 2015.02.
23. Ikegawa Y, Ezoe H, Namba T, Tuda M, Effects of nonspecific adaptive defense by pests on efficiency of biological control by multiple natural enemies., Journal of the Faculty of Agriculture, Kyushu University, 59, 2, 305-311, 2014.09.
24. Tuda M, Kagoshima K, Toquenaga Y, Arnqvist G, Global genetic differentiation in a cosmopolitan pest of stored beans: effects of geography, host-plant usage and anthropogenic factors., PLoS ONE, 10.1371/journal.pone.0106268, 9, 9, e106268, 2014.09, Genetic differentiation can be promoted allopatrically by geographic isolation of populations due to limited dispersal ability and diversification over time or sympatrically through, for example, host-race formation. In crop pests, the trading of crops across the world can lead to intermixing of genetically distinct pest populations. However, our understanding of the importance of allopatric and sympatric genetic differentiation in the face of anthropogenic genetic intermixing is limited. Here, we examined global sequence variation in two mitochondrial and one nuclear genes in the seed beetle Callosobruchus maculatus that uses different legumes as hosts. We analyzed 180 samples from 42 populations of this stored bean pest from tropical and subtropical continents and archipelagos: Africa, the Middle East, South and Southeast Asia, Oceania and South America. For the mitochondrial genes, there was weak but significant genetic differentiation across continents/archipelagos. Further, we found pronounced differentiation among subregions within continents/archipelagos both globally and within Africa but not within Asia. We suggest that multiple introductions into Asia and subsequent intermixing within Asia have generated this pattern. The isolation by distance hypothesis was supported globally (with or without continents controlled) but not when host species was restricted to cowpeas Vigna unguiculata, the ancestral host of C. maculatus. We also document significant among-host differentiation both globally and within Asia, but not within Africa. We failed to reject a scenario of a constant population size in the recent past combined with selective neutrality for the mitochondrial genes. We conclude that mitochondrial DNA differentiation is primarily due to geographic isolation within Africa and to multiple invasions by different alleles, followed by host shifts, within Asia. The weak inter-continental differentiation is most likely due to frequent inter-continental gene flow mediated by human crop trade..
25. Saeki Y, Tuda M, Crowley PH, Allocation trade-offs and life histories: a conceptual and graphical framework., Oikos, 0.1111/oik.00956, 123, 7, 786-793, 2014.07.
26. Tuda M, Li-Hsin Wu, Yamada N, Wang C-P, Wu W-J, Buranapanichpan S, Kagoshima K, Chen ZQ, Teramoto KK, Kumashiro BR, Heu R, Host shift capability of a specialist seed predator of an invasive plant: roles of competition, population genetics and plant chemistry., Biological Invasions, 16, 2, 303-313, 2014.02.
27. T Yahara, F Javadi, Y Onoda, LP de Queiroz, DP Faith, DE Prado, M Akasaka, T Kadoya, F Ishihama, S Davies, JWF Slik, T Yi, K Ma, C Bin, D Darnaedi, RT Pennington, M Tuda, et al., Global legume diversity assessment: concepts, key indicators, and strategies., TAXON, 62, 2, 249-266, 2013.04.
28. Tuda, M., Evolutionary diversification of bruchine beetles: climate-dependent traits and development associated with pest status. , Bulletin of Entomological Research, 101(4), 415-422., 2011.07.
29. Vamosi SM, den Hollander MD, Tuda M, Egg dispersion is more important than competition type for herbivores attacked by a parasitoid., Population Ecology, 53(2): 319–326, 2011.04.
30. Arnqvist, G., Dowling, D.K., Eady, P., Gay, L., Tregenza, T., Tuda, M. and Hosken, D.J., The genetic architecture of metabolic rate: environment specific epistasis between mitochondrial and nuclear genes in an insect., Evolution, 64, 3354-3363, 2010.12, 近年、ミトコンドリア(mt)DNAが、エネルギー生産する酵素複合体を一緒に作る核遺伝子と共進化することが解明されている。これはmt遺伝子と核遺伝子の間のゲノム間エピスタシスが生物個体全体の代謝表現型に影響することを示唆する。そこでヨツモンマメゾウムシの複数のmt系統と核系統間で組み合わせ交配し、代謝率を2つの異なる温度下で測定した。代謝率はmtと核の系統間交互作用と温度に影響された。塩基配列データは、mtの遺伝的変異がこの交互作用の結果を決めることを示唆した。この実験は、2つのゲノムの遺伝的相互作用と遺伝子型x遺伝子型x環境間交互作用を明らかにした。これらの結果は1. 生活史進化一般、特に温度適応の複雑性に洞察を与え、2. 非中立的なmtDNA多型の維持機構を示唆する。
The extent to which mitochondrial DNA (mtDNA) variation is involved in adaptive evolutionary change is currently being reevaluated. In particular, emerging evidence suggests that mtDNA genes coevolve with the nuclear genes with which they interact to form the energy producing enzyme complexes in the mitochondria. This suggests that intergenomic epistasis between mitochondrial and nuclear genes may affect whole-organism metabolic phenotypes. Here, we use crossed combinations of mitochondrial and nuclear lineages of the seed beetle Callosobruchus maculatus and assay metabolic rate under two different temperature regimes. Metabolic rate was affected by an interaction between the mitochondrial and nuclear lineages and the temperature regime. Sequence data suggests that mitochondrial genetic variation has a role in determining the outcome of this interaction. Our genetic dissection of metabolic rate reveals a high level of complexity, encompassing genetic interactions over two genomes, and genotype x genotype x environment interactions. The evolutionary implications of these results are twofold. First, because metabolic rate is at the root of life histories, our results provide insights into the complexity of life-history evolution in general, and thermal adaptation in particular. Second, our results suggest a mechanism that could contribute to the maintenance of nonneutral mtDNA polymorphism..
31. Arnqvist, G., Tuda, M., Sexual conflict and the gender load: correlated evolution between population fitness and sexual dimorphism in seed beetles., Proceedings of the Royal Society B, 277, 1345-1352, 2010.04, 雌雄はゲノムの大半を共有しながらも選択は異なる。性的対立する遺伝子座は理論上、集団内の性的負荷を引き起こす。しかし、遺伝子座内性的対立(ISC)が移行的な進化的状態(性的二型(SD)の進化により対立は急速に解消)なのか、慢性的な適応障害なのか、は現在明らかでない。同じ条件下では、ISCは雌雄において表現される形質の集団適応度とSDの相関進化として現れるはずだ。そこで同じ飼育環境に適応したマメゾウムシの異なる実験室集団間で適応度とSDを比較しISCの効果を試験した。重要な生活史形質である幼生発育期間のSDは適応度と正の関係があり、これは集団適応度と発育期間の相関進化(雌で正、雄で負)によった。雌雄間の遺伝的結合を緩めることで雌雄がそれぞれの異なる適応度ピークへと近づいたと言える。
Although males and females share much of the same genome, selection is often distinct in the two sexes. Sexually antagonistic loci will in theory cause a gender load in populations, because sex-specific selection on a given trait in one sex will compromise the adaptive evolution of the same trait in the other sex. However, it is currently not clear whether such intralocus sexual conflict (ISC) represents a transient evolutionary state, where conflict is rapidly resolved by the evolution of sexual dimorphism (SD), or whether it is a more chronic impediment to adaptation. All else being equal, ISC should manifest itself as correlated evolution between population fitness and SD in traits expressed in both sexes. However, comparative tests of this prediction are problematic and have been unfeasible. Here, we assess the effects of ISC by comparing fitness and SD across distinct laboratory populations of seed beetles that should be well adapted to a shared environment. We show that SD in juvenile development time, a key life-history trait with a history of sexually antagonistic selection in this model system, is positively related to fitness. This effect is due to a correlated evolution between population fitness and development time that is positive in females but negative in males. Loosening the genetic bind between the sexes has evidently allowed the sexes to approach their distinct adaptive peaks..
32. Yanagi S, Tuda M, Interaction effect among maternal environment, maternal investment and progeny genotype on life history traits in Callosobruchus chinensis., Functional Ecology, 24, 2, 383-391, 2010.04, 母親の環境条件(前世代の環境preE)に依存して、母親から子への投資量(環境E)が変化するとき、適応度を上げるために子の遺伝子(G)の発現も変化すると予測される。アズキゾウムシにおいて、EとGの遺伝相関の影響を取り除くために近交系の雌を用いて、preEとEに対するGの反応を調べた。高密度(preE)飼育した母親との交配では低密度適応した野外系統の父親の子(G)が、低密度(preE)飼育した母親とでは高密度適応した室内系統の父親の子(G)が、卵サイズ(E)の増大とともに発育期間が急激に短くなり(適応度が上がり)予測を支持した。このような密度依存的な母性効果(preE×E×G交互作用)は、新しい環境における急速な適応進化を可能にする。
1. Transgenerational effects, genetic or non-genetic, affect population dynamics and the evolution of life-history traits. Besides genetic components, the size of gametes (eggs and seeds), simultaneously a parental and progeny character, can mediate environmental condition experienced by a parent. In both animals and arthropods, mothers are known to reduce their egg mass depending on their malcondition.
2. Progeny may also modify their life history traits to increase their own fitness when constrained by maternal investment, which may eventually nullify transgenerational effects on population dynamics and evolution. Such fitness modification by the progeny under new environmental conditions requires phenotypic plasticity interacting with egg mass. We hypothesize that different selective environments should produce inter-population genetic diversification of the response to maternal investment on each egg, which would be detected as a paternal genotype x environment x previous (i.e. maternal) environment (G x E x preE) interaction in progeny fitness.
3. To evaluate the contribution of maternal non-genetic resource and the genetic component separately, we used an inbred-isofemale-line approach to eliminate the influence of the genetic correlation between egg mass and other life history traits, in the adzuki bean beetle, Callosobruchus chinensis. The females were reared at either high or low densities to generate variability in egg resources. To test the additive or interactive effect of genotype, non-genetic egg resources, and maternal environment on the life history traits of the progeny, they were crossed with males from laboratory and wild strains that had been subjected to different levels of population density.
4. The G x E x preE interaction effect was detected on the correlation structure between egg mass and development time: In the offspring of mothers reared at low density, the negative correlation between egg mass and development time was higher with lab strain fathers, whereas in the offspring of mothers reared at high density, the negative correlation was higher with the wild strain fathers.
5. Our results indicate a genetic difference in the response of development time but not of adult mass to environmental variation in egg mass. Such density-dependent enhancement of maternal effects may destabilize population dynamics and accelerate evolution..
33. Ayabe, Y., Tuda, M., Mochizuki, A. , Benefits of repeated mine trackings by a parasitoid when the host leafminer has a tortuous feeding pattern., Animal Behaviour, 76 (6), 1795-1803, 2008.12.
34. Kergoat, G.J., Silvain, J.-F., Delobel, A., Tuda, M., Anton, K.-W., Defining the limits of taxonomic conservatism in host-plant use for phytophagous insects: Molecular systematics and evolution of host-plant associations in the seed-beetle genus Bruchus Linnaeus (Coleoptera: Chrysomelidae: Bruchinae)., Molecular Phylogenetics and Evolution, 43(1), 251-269, 2007.04.
35. Kergoat, G.J., Silvain, J.-F., Buranapanichpan S., Tuda, M., When insects help to resolve plant phylogeny: Evidence for a paraphyletic genus Acacia from the systematics and host-plant range of their seed-predators., Zoologica Scripta, 36 (2), 143-152, 2007.01.
36. Tuda, M., Ronn, J., Buranapanichpan, S., Wasano, N., Arnqvist, G., Evolutionary diversification of the bean beetle genus Callosobruchus (Coleoptera: Bruchidae): traits associated with stored-product pest status., Molecular Ecology, 15(12): 3541-3551, 2006.10.
37. Tuda, M., Matsumoto, T., Itioka, T., Ishida, N., Takanashi, M., Ashihara, W., Kohyama, M. and Takagi, M., Climatic and inter-trophic effects detected in 10-year population dynamics of biological control of the arrowhead scale by two parasitoids in southwestern Japan., Population Ecology, 48(1), 59-70, 2006.01.
38. M. Tuda, M. Shimada, Complexity, evolution and persistence in host-parasitoid experimental systems, with Callosobruchus beetles as the host., Advances in Ecological Research, 10.1016/S0065-2504(04)37002-9, 37, 37-75, 37, 37-75, 2005.01.
39. Tuda, M., Wasano, N., Kondo, N., Horng, S.-B., Chou, L.-Y. and Tateishi, Y., Habitat-related mtDNA polymorphism in a stored-bean pest Callosobruchus chinensis (Coleoptera: Bruchidae)., Bulletin of Entomological Research, 10.1079/BER2003277, 94, 1, 75-80, 94(1), 75-80, 2004.01.
40. Tuda, M., Shima, K., Johnson, C. D. and Morimoto, K., Establishment of Acanthoscelides pallidipennis (Coleoptera: Bruchidae) feeding in seeds of the introduced legume Amorpha fruticosa, with a new record of its Eupelmus parasitoid in Japan., Applied Entomology and Zoology, 36, 3, 269-276, 36 (3), 269-276, 2001.01.
41. Tuda, M., Chou, L.-Y., Niyomdham, C., Buranapanichpan, S. and Tateishi, Y., Ecological factors associated with pest status in Callosobruchus (Coleoptera: Bruchidae): high host specificity of non-pests to Cajaninae (Fabaceae)., Journal of Stored Products Research, 10.1016/j.jspr.2004.09.003, 41, 1, 31-45, 41(1), 31-45, 2005.01.
42. M. Tuda, M.B. Bonsall, Evolutionary and population dynamics of host-parasitoid interactions., Researches on Population Ecology, 10.1007/PL00011985, 41, 1, 81-91, 41(1),81-91, 1999.01.
43. M. Tuda, M. Shimada, Developmental schedules and persistence of experimental host-parasitoid systems at two different temperatures, Oecologia, 103(3),283-291, 1995.01.
Works, Software and Database
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1. 高 思奕, 津田みどり, ミカンとヤノネカイガラムに対する異なる元素ナノ粒子の葉面散布の影響 Impact of foliar applications of different elements of nanoparticles on mandarin orange and scale insects, 第71回日本生態学会大会, 2024.03.
2. Tuda M, Leroy E, Gao S, San PP, Ellies-Oury MP, Egg size plasticity under climate change is affected by endosymbiotic bacterial infection, 第39回個体群生態学会大会, 2023.10.
3. Tuda M, Warming reduces the density-dependent divergence in emergence time for two competing parasitoid species, iTHEMS Biology Seminar (理化学研究所 数理創造プログラム), 2023.03.
4. Gao S, Tuda M, Control of scale insects on mandarin orange Citrus unshiu by foliar applications of nano-micronutrients, 第67回日本応用動物昆虫学会大会, 2023.03.
5. San PP, Tuda M, Impacts of endosymbiotic Wolbachia bacterial diversity, parasitoid diversity, and climate change on host–parasitoids system persistence, 第69回日本生態学会大会, 2022.03.
6. San PP, Tuda M, Effects of Wolbachia infection on life history traits in azuki bean beetle Callosobruchus chinensis and its parasitoids under climate change, 第65回日本応用動物昆虫学会大会, 2021.03.
7. Fukuda K, Tuda M, Mechanism of stable polymorphism of antennal segments number: Trade-off between pre- and post-copulatory fitness in a seed beetle species, XXV International Congress of Entomology, 2016.09.
8. Tuda M, Aung TL, Lwin TH, Kagoshima K, Mori K, Tashiro K, Effect of atmospheric CO2 rise on population size, development and gene expression is different between populations of a seed beetle, XXV International Congress of Entomology, 2016.09.
9. Takagi M, Nakahira K, Tuda M, Biological control of alfalfa weevil under unstable paddy field environment in Japan, XXV International Congress of Entomology, 2016.09.
10. Tuda M, Tani S, Iwase S, Saeki Y, Mori K, Tashiro K, Host-plant and genetic effects on herbivore's fitness and gene expression, The 31st Annual Meeting of the Society of Population Ecology, 2015.10.
11. Saeki Y, Sugawara Y, Tuda M, Switzer PV, Effect of foraging behavior on correlates of dispersal ability in male and female Japanese beetles, 52nd Annual Conference of the Animal Behavior Society, 2015.06.
12. Tuda M, Host-plant change and its mechanism in invasive pest beetles., Symposium on invasive insects: current trends and future directions in research, 2015.02.
13. Midori Tuda, Than Lin Aung, Kumiko Kagoshima, Yasufumi Nakamichi, Eric Wajnberg, Host-parasitoid population dynamics and individual behavior under environmental CO2 rise or species invasion., Netherlands-Japan Seminar on Parasitoid Biology, 2014.08.
14. Than Lin Aung, 津田 みどり, Effect of environmental CO2 concentration on host and parasitoid population dynamics: Is it predictable based on intraspecific competition type?, Annual Meeting of the Society of the Population Ecology, 2013.10.
15. Saeki Y, Tuda M, Crowley P, The size-number trade-off in clonal broods of a parasitic wasp: Responses to the amount and timing of resource availability., Annual Meeting of Society of Population Ecology, 2012.10.
16. Tuda M, Nakamichi Y, Linking community dynamics to population and individual behavior., Second Entomophagous Insects Conference, 2011.06, Three-species systems allow an understanding of irregular, complex population dynamics of multiple species assemblages, with emerging effects of indirect interactions. We focused on a laboratory system consisting of a bruchine species Callosobruchus chinensis as a host and two parasitoids, a chalcid Anisopteromalus calandrae and a braconid Heterospilus prosopidis, with each species introduced sequentially.
With a parameterized semi-mechanistic model, we found the introduction of a second parasitoid (H. prosopidis) destabilized the dynamics of host-parasitoid (A. calandrae) interaction towards chaos. Comparison of parameters before and after the introduction indicated that the parameter that was altered by the introduction was solely the mutual interference in A. calandrae. Finally, to confirm the parameter change detected at the population level, we show our behavioral observation through CCD video camera of the interference between A. calandrae females with a H. prosopidis female when parasitizing their common host..
Membership in Academic Society
  • The Molecular Biology Society of Japan
  • Entomological Society of America
  • International Organisation for Biological Control
  • Japan ICIPE Association
  • Entomological Society of Japan
  • Society for the Study of Evolution
  • Society of Evolutionary Studies, Japan
  • Society of Population Ecology
  • Ecological Society of Japan
  • Japanese Society of Applied Entomology and Zoology
  • Japanese Society for Mathematical Biology
Educational Activities
Graduate courses and laboratory courses for ecology, population biology, ecosystem sciences and biological control.

"Dictionary for Ecology", "Introduction to Ecology", "Encyclopedia of Zoology"
Other Educational Activities
  • 2006.01.
  • 2004.01.
Professional and Outreach Activities
JICA training course for 'Basic Molecular Biology' (lecture and excercises), 2017.9.12-15.、

Invited lectures:

Multiple-species chaos: time-series analysis on 1 host-2 parasitoid laboratory systems by mechanistic nonlinear model. 2002.10.23. IV Hakata International Symposium on Chaos and Nonlinear Time-series

Relation between population and evolutionary dynamics of host-parasitoid system. Joint Research Project for Regional Ecosystems "Interspecific interactions and space"

Effect of winter temperature on biological control system: case study on 2 introduced parasitoids for control of citrus pest, the arrowhead scale, Unaspis yanonensis. 1999.11.27.,IGBP/GAIM meeting.