Host stage preference and reproductive fitnessof Aphidius eadyi(Hymenoptera: Aphidiidae) onAcyrthosiphon pisum(Hemiptera: Aphididae)

Abstract

Host stage preference by Aphidius eadyiStarý, González & Hall on pea aphid, Acyrthosiphon pisum (Harris), and its effects on the reproductive fitness of A. eadyi, were studied in the laboratory at 20 ± 1°C and RH 60-70% with a photoperiod of 16 h light: 8 h dark. Aphidius eadyi females accepted aphids of all stages but preferred fourth instar nymphs and adults for oviposition. Females developed increasingly faster with the increase of host stages, and males developed faster than females in all host stages. The sex ratio of resulting parasitoids was close to 1:1 from all host stages. The egg load and body size of A. eadyi progeny at emergence increased with increasing host stage at the time of parasitisation. The host stage had nonlinear relationships with the number of eggs laid and aphids parasitised by A. eadyi, and the body size of its resulting progeny. Both host stage and body size of resulting parasitoid progeny affected the egg load of newly emerged parasitoids but the latter had more effect. The fourth instar aphids appeared to be the most appropriate hosts for the mass-rearing programme because they gave the best fitness return for the parasitoids. The field release of parasitoids

Host instar preference and functional response of Aphidius transcaspicus, a parasitoid of mealy aphids (Hyalopterus species)

“…Coquerel (Volkl et al 1990), preferred 4th instars and adults of Aphis glycines (Lin and Ives 2003), but 1st and 2nd instars of Myzus persicae and Aphis gossypii (Perdikis et al 2004). A. eadyi also showed a preference for 4th instars and adults of Acyrthosiphon pisum (He et al 2005). However, most Aphidius species, such as A. transcaspicus, show a preference for mid instars of their aphid hosts, as is the case for A. ervi attacking Acyrthosiphon pisum (Ives et al 1999), and Aulacorthum solani (Henry et al 2005).…”

“…Host instar preference among Aphidius spp. appears to be species specific and also to depend on the relative sizes of the different host species attacked (Liu et al 1984;Hagvar and Hofsvang 1991;Weisser 1995;Villagra et al 2002;Perdikis et al 2004;Colinet et al 2005;He et al 2005;Henry et al 2005). Thus, A. colemani showed no preference among instars or morphs of Pentalonia sp.…”

“…The host instar preferences of aphidiine parasitoids are known to be host and parasitoid species specific (e.g. Walker and Hoy 2003;Perdikis et al 2004;He et al 2005;Henry et al 2005), and while invulnerable instars seldom if ever occur, a strong preference for younger instars (e.g. Perdikis et al 2004) may nonetheless contribute to population persistence.…”

Honeydew as a source of nutrition for Lysiphlebus testaceipes (Cresson) (Hymenoptera: Braconidae): effect of adult diet on lifespan and egg load

“…Wasp body size is known to affect egg load (Chau & Mackauer ; He et al . ), so, in this study, HTL was used as a covariate to correct the egg load of wasps for size. A regression analysis was used to test the relationship between HTL and egg load: data from the three carbohydrate diets from 48 to 96 h feeding durations were used in the analysis.…”

Effects of host stage and number of feeding larvae on parasitism success and fitness in the coleopteran parasitoid, Dastarcus longulus Sharp (Coleoptera: Bothrideridae)

“…In several parasitoid wasps, the fitness elements (developmental rate, body size or egg load) of the progeny increased with progressive host stages at the time of parasitism (e.g., Nechols and Kikuchi, 1985;Bell et al, 2003;He et al, 2005). As D. longulus parasitizes larvae, pupae, and adults of M. alternatus, the fitness of the progeny is expected to differ with the host stage.…”