Effects of temperature on predation by the stinkbugsPicromerus bidensandPodisus maculiventris(Heteroptera: Pentatomidae) on noctuid caterpillars

Abstract

AbstractEnvironmental risks associated with the use of non-indigenous organisms for augmentative biological control have received growing attention. In Europe, the native pentatomid predatorPicromerus bidens(Linnaeus) has been considered a potential alternative to the North American pentatomidPodisus maculiventris(Say) for the control of lepidopteran, coleopteran and hymenopteran defoliator pests. In the current study, prey consumption and developmental duration of the predatory stages ofP. bidensandP. maculiventriswere investigated at three temperatures (18, 23 and 27°C) in the laboratory using caterpillars ofSpodoptera littoralisas prey. Development time from second to fifth instar was longer forP. bidensthan forP. maculiventris, taking on average 17–44 and 14–32 days, respectively, at the different temperatures. Total nymphal consumption of fourth instarS. littoraliscaterpillars indicated a greater voracity ofP. bidensas compared withP. maculiventrisat both the low and high temperatures tested (18 and 27°C). At 23°C, however, the predation rate ofP. maculiventrisnymphs exceeded that ofP. bidensnymphs. Effect of temperature on the functional response ofP. bidensto densities of fourth instarSpodoptera exiguawas assessed on potted green bean plants. Female adults ofP. bidensexhibited a type II functional response at 18 and 23°C but a type III response at 27°C. Searching efficiency was not affected by temperature but handling time decreased from 4.2 to 1.4 h as temperature increased from 18 to 23°C. However, the predator spent twice as much time handling prey at 27°C (2.9 h) than at 23°C. This study indicates high predation rates ofP. bidensat a wide range of temperatures and suggests that the species may be a valuable asset for the biological control of defoliating caterpillars, provided that obstacles to its mass production can be overcome.