Effects of Adult Behavior on Larval Survivorship of a Major Predator of Tropical Mosquitos

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9408143 Fincke Abstract A major assumption in biology is that over evolutionary time, males that obtain the greatest number of matings (i.e., fertilizations) make the greatest contribution to the next generation. In contrast, females are thought to be limited, not by the number of matings they obtain, but by the number of eggs or embryos they can physically produce. These basic assumptions have rarely been tested for animals that do not have parental care (i.e., the majority of species) because it is usually impossible to follow the survivorship of offspring of known parents under natural conditions. In the New World tropics, males of an unusual damselfly defend water-filled tree holes where females lay their eggs. The offspring of known adults will be determined using a DNA- fingerprinting technique. Survivorship of offspring to emergence (adulthood) will be measured for all males and females using a given tree hole. Although mosquito larvae are the major source of food for larval damselflies, larger damselflies readily cannibalize smaller ones. Females lay many more eggs in a given hole than the number of individuals that emerge there. Experiments are designed to determine whether a female that lays an excess of eggs in one hole, thereby promoting cannibalism among sibs, produces larger or faster-developing offspring than a female that lays a few eggs in many holes. Other experiments test whether or not an adult male stops defending a particular hole once the chances of cannibalism of younger offspring by older siblings become high. Dr. Fincke's research will determine the extent to which male and female behavior has been shaped by evolution to produce few, high-quality offspring at the expense of producing numerous offspring. Because this damselfly is the major predator of forest mosquito larvae, the research is directly relevant to understanding the biological control mechanisms of several mosquito species that are vectors of human diseases in the New World tropics.