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Impact of Prey Density and Facultative Plant Feeding on the Life History of the Predator Podisus maculiventris (Heteroptera: Pentatomidae)
Editor(s): Oscar Alomar; Robert N. Wiedenmann
Author(s): Robert N. Wiedenmann, Jesusa Crisostomo Legaspi, Robert J. O’Neil
Print Publication Date: 1996

The pentatomid predator Podisus maculiventris (Say) is found in diverse agricultural and nonagricultural habitats, and has been reported to feed on plants as well as >75 prey species. Field-cage studies have shown that the predator found few prey when prey were at densities likely to have been encountered by the predator in the field. Attack rates averaged ≈0.5 attacks per day at lowest prey densities but increased linearly at prey densities that were comparable to outbreak pest densities. Even the linearly increasing attack rates were of a small magnitude, reaching a level of only 2 attacks per day at the greatest prey densities. Despite attacking few prey, the predator persists in many habitats. In light of low attack rates, laboratory experiments were conducted to determine the impact of such attack rates on predator life history attributes such as survivorship, fecundity, and body mass, as well as lipid storage. When prey were provided at infrequent intervals, P. maculiventris maintained survivorship but at the cost of lower reproduction. The decreases in reproduction, measured as numbers of eggs oviposited and as eggs stored in the ovaries, resulted from an apparent trade-off in which scarce energy was allocated to lipid storage rather than to egg production. Predator survival when food was scarce was enhanced by its ability to feed on plant material. Phytophagy provided the predator with water and possibly carbohydrates, which may have been used for short-term energy needs. Facultative phytophagy by P. maculiventris apparently enhances the ability of the predator to survive and maintain populations in crop habitats during times of prey scarcity. By being in the habitat before the population buildup of an herbivore, this predator may deter increases of the herbivore sufficiently that pest status is not achieved. As a result, facultatively phytophagous predators, such as P. maculiventris may offer some benefits for use in an IPM strategy. Such predators cannot reduce populations of a pest species after economic damage has occurred, because of the low magnitude of the functional response. However, the benefits such predators offer may be to keep the population of the potential pest below damaging levels long enough to avert economic losses.

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