|Legaspi, JR., Benjamin - STATE OF FLORIDA|
Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 9, 2004
Publication Date: October 1, 2004
Citation: Legaspi, J.C., Legaspi, Jr., B.C. 2004. Does a polyphagous predator prefer prey species that confer reproductive advantage?: case study of Podisus maculiventris. Environmental Entomology. 33(5):1401-1409. Interpretive Summary: The spined soldier bug feeds on over 75 insect species including several important pests. The bug is reared and sold commercially in both Europe and North America. An important concept in biology is that living organisms seek to maximize their reproduction. When given a choice of different prey species, a logical prediction would be that a predator would prefer to consume those that allowed it to lay more eggs because of say, better nutritional quality. USDA, ARS scientists at the Florida A&M University in Tallahassee, FL, tested the theory that the spined soldier bug would prefer to eat nutritious prey that allowed it to lay the greatest number of eggs. We also dissected adults of different ages to see if the bug was "synovigenic", meaning it produced eggs during its lifetime. Given a choice of beet army worm, fall army worm, cabbage looper, greater wax moth and yellow mealworm, the spined soldier bug preferred to consume beet armyworm. However, most eggs were laid when bugs were fed the cabbage looper. We discuss factors other than maximal egg production that may dictate prey preference. Dissections showed that adult females are synovigenic; they continue to produce eggs during their lifetimes and do not hatch with a full egg complement. Future research will identify the egg-production factors in cabbage looper and these will be used to improve artificial diets.
Technical Abstract: The purpose of this study was to determine whether preferred prey of Podisus maculiventris (Say) (Heteroptera: Pentatomidae) adult females also conferred maximal fecundity, and whether the predator displayed synovigenic or pro-ovigenic reproduction. Adult females were simultaneously offered: Spodoptera exigua, S. frugiperda, Trichoplusia ni, Galleria mellonella and Tenebrio molitor as prey. Afterwards, adult P. maculiventris females were provided one of each prey species for life. This experiment was repeated over four durations: 7, 15, 22, and 30 days. After each trial, egg load dissections were performed, and numbers of mature and immature eggs were recorded. Podisus maculiventris displayed a preference of beet armyworm, however, few significant differences were found in cumulative numbers of eggs laid under the different prey treatments. Only in the 22-day trial were more eggs laid when feeding on the cabbage looper. Egg load dissections revealed total number of eggs and numbers of mature eggs declined significantly with predator age. However, numbers of immature eggs increased. The mean number of mature eggs in 7-day old predators represented only about 5% of mean cumulative numbers of eggs laid by 30-day old predators. Therefore, P. maculiventris female adults showed no preference for prey species that conferred reproductive advantage, and P. maculiventris is strongly synovigenic. The implications of these results are discussed from the context of P. maculiventris as a biological control agent.