Behavioral responses to specific prey and host plant species by a generalist predatory coccinellid (Cryptolaemus montrouzieri Mulsant)

Abstract

Cryptolaemus montrouzieri is a generalist coccinellid used in the biocontrol of soft scale insects and mealybugs. However, the success of biocontrol field releases is variable. In the native range of the beetle, a close geographical and temporal association between C. montrouzieri and native pseudococcids on Araucaria cunninghamii (hoop pine) has been demonstrated. We investigated the feeding and behavioral responses of C. montrouzieri to various combinations of prey and host plants. These experiments included orchard trees and the pest species against which the beetle is released as a biocontrol agent, as well as endemic plant and prey species with which it is associated in its native range. Beetle oviposition rate was reduced but not prevented by the absence of prey of a suitable life stage. In no-choice tests C. montrouzieri fed more readily on Pseudococcus sp. mealybugs, the genus with which it is most regularly associated in its native range. Olfactometer trials demonstrated that C. montrouzieri responds more quickly to the Australian native mealybug, Ps. araucariarum, than other species. In the same trials C. montrouzieri actively avoided Citrus sp. fruit. Olfactometer trials did not otherwise show a clear response to any prey or host plant combination. This is in contrast to the associations recorded in long term field observations of the beetle in its native range. We conclude that behavioral investigations of generalist predators should include the prey and plant associations that are most commonly recorded within the original distribution of the predator.