Functional Responses of Coccinella undecimpunctata and Chrysoperla carnea to their Aphid Prey under Semi-Field Conditions
Journal of Plant Protection and Pathology
Understanding the interactions between predator and prey is the basis for creating a strategy for the biocontrol of aphids. One of the most informative methods to understand these interactions is the functional response. In this study, the predation efficiency, of the second-instars of Coccinella undecimpunctata L. and Chrysoperla carnea (Stephen) to Aphis craccivora and Aphis gossypii were evaluated. The experiments were carried out under semi-greenhouse conditions at predator: prey ratios
... or: prey ratios ranging from 1: 20 to 1: 100 per cage. The decline in the predation rates with increasing density of A. craccivora by each of both predators fits the type II and type I functional responses for C. undecimpunctata and C. carnea, respectively. While, both predator species exhibited a type I responses to changing in A. gossypii densities. The type II functional response estimates showed that C. carnea had greatest attack rate and shorter handling time on A. craccivora than those for the type I of C. undecimpunctata. On A. gossypii, these values were better for C. undecimpunctata larvae than C. carnea. Theoretically, the highest number of prey that could be eaten by a single predatory larva of C. undecimpunctata and C. carnea within a day (T/Th) was 18.31 and 9.30 of A. craccivora, and 24.89 and 16.91 of A. gossypii, respectively. Although, the type of response was generally a type I with a constant mortality rate regardless the prey density increased or not, this type might be turned to type II, on longterm, as the predator establishes.