Masako Katsuki

Learn More
Insect body temperature is usually determined by ambient temperature. Therefore, most biochemical and physiological processes underlying behavioural patterns are temperature dependent. Mating duration is also dependent on temperature, and therefore temperature should influence on sperm transfer and female remating frequency. In the adzuki bean beetle,(More)
Traditional concepts of sexual selection and sexual conflict make different predictions about the costs and benefits to females of exposure to males with higher mating success. The traditional concepts of sexual selection assume that females benefit from their mate choices, whereas sexual conflict assumes that the females suffer greater costs by mating with(More)
Female mate choice and male-male competition are the typical mechanisms of sexual selection. However, these two mechanisms do not always favour the same males. Furthermore, it has recently become clear that female choice can sometimes benefit males that reduce female fitness. So whether male-male competition and female choice favour the same or different(More)
Males and females frequently have different fitness optima for shared traits, and as a result, genotypes that are high fitness as males are low fitness as females, and vice versa. When this occurs, biasing of offspring sex-ratio to reduce the production of the lower-fitness sex would be advantageous, so that for example, broods produced by high-fitness(More)
The West Indian sweet potato weevil Euscepes postfasciatus (Fairmaire) is a troublesome pest insect of sweet potato that originally came from the Caribbean, but is now expanding its distribution into the Pacific Islands. Although sterile insect techniques have been used against this pest in a demonstration experiment on Kume Island [Ohno et al. (2006)(More)
Females prefer male traits that are associated with direct and/or indirect benefits to themselves. Male-male competition also drives evolution of male traits that represent competitive ability. Because female choice and male-male competition rarely act independently, exploring how these two mechanisms interact is necessary for integrative understanding of(More)
It is now generally recognized that it is necessary to examine how sexual selection operates across the lifespan of a male, in order to understand the total sexual selection in action. However, less attention has been paid to the fact that selection pressures can change in response to varying environmental conditions. Here, we examine male allocation to(More)
Polyandry creates the opportunity for post-mating sexual selection, and pre- and post-mating sexual selection affects male traits. Investigation of selection pressures in both pre- and post-mating stages is necessary to understand sexual selection. In the cigarette beetle Lasioderma serricorne, we found previously that males that mated faster are thought to(More)
The seed beetle Callosobruchus maculatus larvae exhibit two types of resource competition: scramble, in which a resource is shared, and contest, in which the resource is monopolized. This difference in larval behavior results in different adult densities. Under contest competition, adult density remains constant regardless of larval density, but under(More)
Although polyandry is common, it is often unclear why females mate with multiple males. While polyandry may provide females with direct or indirect fitness benefits, it can also be costly. Thus, investigating both the costs and benefits of polyandry is needed to understand the evolution of female polyandry. Here, we investigated the potential benefits and(More)