Long & Medium-Term Research: Foraging and Sex Allocation Behavior of An Autoparasitoid in A Spatially-Structured Environment. This award recommendation is made under the Program for Long & Medium-Term Research at Foreign Centers of Excellence. The program seeks to enable U.S. scientists and engineers to conduct long-term research abroad at research institutions of proven excellence. Awards provide opportunities for the conduct of joint research, and the use of unique or comple. mentary facilities, expertise and experimental conditions in foreign countries. This award for a proposal sponsored by Dr. David Pimentel will support a six-and-one-half month-post-doctoral research visit to the United Kingdom by Dr. Martha S. Hunter to work with Dr. H.C.J. Godfray at the Imperial College at Silwood Park, on "Foraging and Sex Allocation Behavior of An Autoparasitoid in A Spatially-Structured Host Environment." Parasitic wasps called "autoparasitoids" offer a unique opportunity to test Fisher's (1930) theory on the evolution of the sex ratio. Fisher's principle that organisms should invest equally in each sex generally leads to a 1:1 sex ratio. In autoparasitoids, however, males and females are laid in different hosts; thus the "cost" of each sex and the predicted sex ratio varies with the changing host environment. At high total host densities, wasps should be egg-limited, and prefer to oviposit in the less abundant host type, thus producing a sex ratio which is close to 1:1. At low host densities, wasps should be host-limited and simply oviposit in hosts as they encounter them, thus producing a sex ratio which reflects the relative abundance of the two host types. The investigator proposes to test this extension of Fisher's theory with the autoparasitoid Encarsia tricolor in a spatially structured host environment. In particular, she will evaluate the effects of the relative availability of the two host types, total host density, and spatial structure of the host population on sex ratio. Since sex allocation is central in determining the population dynamics of autoparasi- toids, this research will help bridge the gap between sex ratio theory and population dynamics, and will contribute to evaluating autoparasitoid species as biological control agents. The award recommendation provides funds to cover, as appropriate, international travel, local travel abroad, stipend, dependents' allowance if applicable, and a flat administrative allowance of $250 for the U.S. home institution.
