Functional response of Scymnus syriacus (Coleoptera: Coccinellidae) on Aphis gossypii (Hemiptera: Aphididae) reared on cucumber

Abstract

The functional response of both fourth larval instar and adult stage of the predator Scymnus syriacus was studied on cotton aphid. Both stages exhibited a type II functional response when fed on six different densities of cotton aphid nymphs (5, 0, 20, 40, 80, and 160 nymphs/Petri dish). Rogers' model was found to be the most suitable for the data. Predation efficiency varied with the life stage and temperature, as handling time (T_h) decreased and attack rate (α) increased for both stages when the temperature rose from 22°C to 28°C. Females were the most efficient, with the highest attack rate (0.204 nymphs/hour) and shortest handling time (0.414 hours) at 28°C. The study confirmed that adult females are the most suitable biological control agent against the cotton aphid, demonstrating superior efficacy, especially at higher temperatures and lower prey densities.