host stage preference and age-specific functional response of praon volucre (hymenoptera: braconidae, aphidiinae) a parasitoid of acyrthosiphon pisum (hemiptera: aphididae)

the pea aphid, acyrthosiphon pisum (harris) is one of the most important pests of pea throughout the world.host stage preference under choice and no-choice tests and age-specific functional response of praon volucre (haliday) parasitizing a. pisum were investigated. the experiments were carried out under laboratory conditions at 25 ± 1 °c, 60 ± 5% rh and a photoperiod of 14: 10 h (l: d). functional response of p. volucre was evaluated in adult lifetime at seven host densities (2, 4, 8, 16, 32, 64 and 128). praon volucre strongly preferred to oviposit into first and second instar nymphs in both choice and no-choice conditions. parameter estimation of logistic regression revealed type iii functional response for p. volucre in first and second days and type ii from third to the end of parasitoid lifetime. the handling time (th) and searching efficiency (a or b) were estimated using the rogers equation. the shortest and longest handling times were at fourth day (th = 0.19 ± 0.04) and 8th day (th = 0.94 ± 0.15), respectively. the highest searching efficiency (a) was 0.048 ± 0.007 h-1 on third day and lowest searching efficiency was observed at the end of parasitoid lifetime (6th day-8th days). the maximum attack rate ranged from 126.31 nymphs/24 h on fourth day to 25.53 nymphs/24 h on 8th day. the results of this study revealed that the age of adult parasitoid can change the functional response from type iii to type ii, indicating that this factor may contribute to stabilization of parasitoid–prey dynamics.