Effects of host size on sex ration, development time and size ofPimpla turionellae (L.) (Hymenoptera: Ichneumonidae)

Abstract

Pimpla turionellae (L.) (= exarainator F.) is a pupal parasite of many species of Lepidoptera. During propagation of this species for release in Canada against the European pine shoot moth, Rhyacionia buoliana (SCHIFF.), and the spruce budworm, Choristoneura ]umi]erana (CL~.M.), data were obtained oil the influence of the size of the host pupae on sex ratio, development time, and size of the adults. Material and MethodsMated females of P. turio~ellae that had been reared in the laboratory on a number of medium-sized hosts were plaeed singly in cages that measured 4 • 4 • 2 1/2 inches. They were fed daily a 10 per eent solution of honey and sprayed twiee daily with tap water. Pupae of different hosts were introduced into the cage and eaeh was removed as soon as the parasite had laid one egg on it. The hosts were then weighed, placed singly in glass vials, and incubated at 22-24 oC. and 60 q-5 per cent relative humidity. Weight was used as a measure of host size because of differences in shape between moth and butterfly pupae. When the parasites emerged they and the host remains were weighed separately. As this species is arrhenotokous, only data from females that produced both males and females were used. Pupae that did not produce parasites were dissected.Nine speeies of lepidopterous hosts were used. Anagasta k4~hniella (ZELL.) and Galleria mellonella (L.) (Pyralidae) were taken from labo-

Functional response and life history parameters of Apanteles taragamae, a larval parasitoid of Maruca vitrata

“…Parasitism success on one-day-old larvae was the lowest. This was associated with low immature survival, which may be due to limited nutritional resources available in such early instar larvae (Arthur and Wylie 1959;Harvey et al 2004). Hence, the parasitoid took longer to complete its development on one-day-old larvae (Table 1).…”

“…Sex allocation in many parasitoids species was found to be influenced by host age or size at oviposition (Arthur and Wylie 1959;Jones 1982;King 1987). Female wasps were reported to be selective as to the sex of the offspring they deposit in the host (Dicke 1999).…”

“…Thus, the host size selected for oviposition by a female parasitoid affects the size and sex of its progeny (Arthur and Wylie 1959;Jones 1982;King 1987;Dicke 1999;Lacoume et al 2006). In general, large adult parasitoids emerge from large hosts, and a larger proportion of females are produced when larger hosts are selected by the female parasitoid (Dicke 1999).…”

Parasitic Behaviour of Xanthopimpla pedator Fabricius (Hymenoptera: Ichneumonidae) on Tropical Tasar Silkworm, Antheraea mylitta Drury (Lepidoptera: Saturniidae) Reared on Seven Forestry Host Plants in Uttarakhand, India

“…Literature survey does not indicate any specific reason for such intersexual host selection behaviour of X. pedator or in any other species of Ichneumonidae, except that in pimpline, ichneumonids female lay their large size female eggs into larger hosts and male eggs of smaller size into smaller host (Arthur and Wylie, 1959;Kishi, 1970), thus investing most resources to a daughter, leads to increased egg production and greater longevity for oviposition (Charvov, 1982).…”

Biology of Rhembobius quadrispinus (Hymenoptera: Ichneumonidae): Pupal parasitoid of saprophagous species of syrphids (Diptera: Syrphidae)

“…Host size at oviposition closely reflects the amount of food available to the offspring of idiobiont parasitoids that attack non-feeding host stages (eggs or pupae) (Arthur & Wylie, 1959;Corrigan & Lashomb, 1990;Otto & Mackauer, 1998).…”