Functional and numerical responses of the parasitoid wasp, Aphidius matricariae (Hym.: Braconidae) feeding on current lettuce aphid, Nasonovia ribisnigri (Hem.: Aphididae)

unctional and numerical responses of Aphidius matricariae Haliday were studied on Nasonovia ribisnigri Mosely at 20±1°C, 65±5% RH and a photoperiod of 16:8 (L: D) h. Different densities (2, 4, 8, 16, 32 and 64) of third instar nymphs of N. ribisnigri were provided to mated female wasp (< 24 h old) with ten replicates in 24 hours. The functional response was determined using logistic regression and the parameters were estimated by non–linear regression. The results revealed a type II functional response of A. matricariae to different densities of third instar nymphs of N. ribisnigri. Attack rate and handling time were obtained as 0.0367 h–1 and 0.4114 h, respectively. Also, maximum attack rate (T/Th) was estimated 58.33 nymphs. The data of numerical response of A. matricariae indicated that with increase of host density, the average number of mummified aphids in life span of parasitoid increased from 7.8 (density of 2) to 140.7 mummies (density of 64). According to these results, it seems that A. matricariae is potentially suitable biological control agent in suppressing N. ribisnigri population.