Functional Response of Two Coccinellid Predators, Scymnus levaillanti and Cycloneda sanguinea, to the Cotton Aphid, Aphis gossypii

Authors: ALİ ARDA IŞIKBER

Abstract: Functional responses of 2 female coccinellid predators, Scymnus levaillanti and Cycloneda sanguinea, to the cotton aphid, Aphis gossypii, at various temperatures were studied under laboratory conditions. Both coccinellid species showed different functional responses to the cotton aphid. The larger species, C. sanguinea, was seen to eat more aphids than the smaller species, S. levaillanti, at each temperature, due to its greater voracity. The female adults of both coccinellid species feed maximally during the first 3 h and therefore, the increase in fresh weight gain and number of aphids killed by both coccinellid species are much higher during the first 3 h at each temperature than those during the following 3 h intervals. The consumption of cotton aphids by both coccinellid species had a type II functional response at each temperature. The parameters estimated from the type II functional response model suggest that C. sanguinea can be more effective at suppressing cotton aphid populations than S. levaillanti when the cotton aphid populations are large. This is because they have less time to process the cotton aphids and are more efficient searchers, requiring more cotton aphids to reach satiation than S. levaillanti.

Keywords: Coccinellid, Scymnus levaillanti, Cycloneda sanguinea, functional response, aphid density, handling time, attack constant

Full Text: PDF