Koji Tsuchida

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The bumblebee Bombus terrestris is not only an effective pollinator, but also a potential invasive alien species outside its native range. Recently, nearly 30% of queens of the Japanese native species Bombus hypocrita sapporoensis and B. hypocrita hypocrita were estimated to copulate with B. terrestris males in the field, suggesting that indigenous(More)
We surveyed male survival and reproductive performances associated with dimorphism in the Japanese horned beetleAllomyrina dichotoma L. in a secondary forest in 1996. Morphological comparisons between living marked and prey individuals indicated that the larger horned males suffered higher predatory pressure than the smaller ones. The dominant predators of(More)
Beyond helping the queen's reproductive function, the worker caste of Polistes wasps is expected to have an alternative reproductive strategy; to become a replacement queen, following copulation with early males that emerge along with the first brood workers. We analyzed genotypes and chromosome numbers of the early males in a natural population of P.(More)
In social insects, nestmate recognition systems can be dynamic and modulated in response to various kinds of genetic and environmental cues. For example, multiple-queen colonies can possess weak recognition abilities relative to single-queen colonies, due to broader exposure to heritable and environmentally derived nestmate recognition cues.We conducted(More)
Kin-selection theory predicts that a worker prefers to produce her own sons in a colony with monandry and monogyny because relatedness to her sons (0.5) and nephews (0.375) exceeds that to brothers (0.25). In spite of this prediction, recent studies reveal that workers police each other (mutual-worker egg removal) even in monandrous and monogynous colonies.(More)
Several geometrical isomers of 3,13- and 2,13-octadecadien-1-ols and their acetates were synthesized starting from 1,8-octanediol or 1,9-nonanediol utilizing acetylene coupling reactions. In addition to commercially available compounds, all geometrical isomers of each dienyl compound were analyzed by NMR and GC-MS to accumulate chemical data for studies of(More)
In a colony headed by a single monandrous foundress, theories predict that conflicts between a queen and her workers over both sex ratio and male production should be intense. If production of males by workers is a function of colony size, this should affect sex ratios, but few studies have examined how queens and workers resolve both conflicts(More)
The European bumblebee, Bombus terrestris, is an invasive eusocial species whose distribution is expanding greatly beyond its native range because numerous colonies are imported to or locally produced in non-native countries for pollination of agricultural crops. Closely related species exist in Japan where the unrestricted import and use of B. terrestris(More)
Gynandromorphy, or the development of organisms with a combination of male and female morphological features, is common in Hymenoptera. The underlying mechanism is likely associated with the sex-determination system, and studying this phenomenon should lead to a deeper understanding of both embryonic development and sex determination. The reproductive(More)
In social-insect colonies, cooperation among nestmates is generally stabilized by their high genetic similarity. Thus, fitness gained through cooperation drops quickly as the number of reproductive females (queens) increases. In this respect, wasps of the tribe Epiponini have attracted special attention, because the colonies have tens, or even hundreds of(More)