Functional response of Anthocoris nemoralis (Hemiptera: Anthocoridae) to the pear psylla, Cacopsylla pyricola (Hemiptera: Psyllidae): effect of pear varieties

Anthocoris nemoralis (F.) (Hemiptera: Anthocoridae) is one of the most prominent predators of the pear psylla, Cacopsylla pyricola (Forster) (Hemiptera: Psyllidae) and is considered as a biological control agent against this pest. In order to investigate the effects of plant varieties on predation of C. pyricola by A. nemoralis, the functional response of both the sexes of A. nemoralis to pear psylla nymphs was studied on three pear varieties including ‘Shahmiveh’, as a susceptible host plant and ‘Sebri’ and ‘Coscia’, as partially-resistant host plants. Different densities of C. pyricola nymphs were offered to single A. nemoralis and predation proceeded for 24 h. The experiments were carried out under constant environmental conditions (27 ± 1 °C, 70 ± 5% RH and L: D 16: 8 h). Logistic regression and nonlinear least-squares regression were used to determine the type of functional response and to estimate attack rate (a) and handling time (Th), respectively. The results showed a type II functional response on all varieties. The asymptotic 95% confidence intervals, estimated by the model with indicator variable revealed that there was no significant difference between either the attack rates or between handling times of same sex of the predator on the tested varieties. However, when sexes were compared, the females of A. nemoralis had a shorter handling time and higher searching efficiency than the males on all varieties. The maximum predicted daily prey consumption by a female predator (T/Th) was the highest on the susceptible variety. Based on the type of functional response and its parameter values, the effectiveness of A. nemoralis was not affected by plant resistance; these findings may be promising for the integration of the partially-resistant varieties and A. nemoralis in sustainable pest management programs against the pear psylla. The implications of the results for biological control of pear psylla were discussed in a tritrophic context.