Larval Cannibalism and Intraguild Predation Between the Introduced Green Lacewing, Chrysoperla carnea, and the Indigenous Trash-Carrying Green Lacewing, Mallada desjardinsi (Neuroptera: Chrysopidae), as a Case Study of Potential Nontarget Effect Assessment

Abstract

Abstract To study the potential competitive risk of the introduced Chrysoperla carnea (Stephens) on the indigenous trash-carrying chrysopid Mallada desjardinsi (Navas), we studied the occurrence of cannibalism and intraguild predation (IGP) at different prey densities. In C. carnea, 100% cannibalism was observed in the absence of aphids. In M. desjardinsi, cannibalism was also observed, but absence of cannibalism occurred at 35% in pairs of second- + third-instar larvae and at 70% in pairs of third- + third-instar larvae. In pairs of M. desjardinsi larvae whose trash package had been artificially removed, all third-instar larvae ate second-instar larvae. The trash package may play a role in the reduced mortality of younger larvae by cannibalism. IGP occurred in all pairs. In the absence of aphids, the interaction was symmetric between second-instar larvae, but asymmetric for second- versus third- and third- versus third-instar larvae, and the interaction was similar when M. desjardinsi larvae with or with...