Foraging efficiency of Lysiphlebus fabarum Marshall (Hymenoptera: Aphidiidae) parasitizing the black bean aphid, Aphis fabae Scopoli (Hemiptera: Aphididae), under laboratory conditions

Foraging efficiency of Lysiphlebus fabarum Marshall, the most abundant and effective parasitoid of the black bean aphid, Aphis fabae Scopoli, in terms of functional and numerical responses and mutual interference, was studied on broad bean plants in a growth chamber at 21 °C, 70 ± 5% RH and a photoperiod of 16:8 (L:D) h. Using logistic regression, a type II functional response was determined for L. fabarum. Nonlinear least-square regression was used to estimate the searching efficiency (a') and handling time (Th). Numerical response of L. fabarum to cumulative host densities was partially linearly increasing. Nicholson's model and linear regression were used to determine the per capita searching efficiency and interference coefficient, respectively. In general, the per capita parasitism and, consequently, the per capita searching efficiency decreased significantly as parasitoid density increased. Mutual interference and quest constants were − 0.508 and − 0.697, respectively. The results of this study suggest that both the host and parasitoid densities have no significant impact on the progeny sex ratio. The information provided here will be useful in assessing the efficiency of L. fabarum as a biological control agent of A. fabae, devising mass-rearing protocols and implementing release programs for this parasitoid.