Abstract
Hyssopus pallidus (Askew) (Hymenoptera: Eulophidae) is a gregarious ectoparasitoid of late larvae of the codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae). In the present work reproduction and the development and morphology of the immature stages were studied. Five larval instars were differentiated by the shape and size of the mandibles. The larvae are hymenopteriform with a weakly sclerotized head and 13 segments. The first instar has four pairs of spiracles, while the other four instars have nine pairs. Under laboratory conditions of 22-24°C and 60-80% RH the egg stage lasted 1.5 days, the larval instars 6.3 days, and the pupal stage 7.9 days in females and 7.2 days in males. The duration of each of the five larval instars (L1-L5) is approximately 1, 0.5, 0.75, 0.75 and 3.5 days, respectively. Male and female development time does not differ significantly in the egg and larval stages, but differences are highly significant in the pupal stage. Male and female pupae can be differentiated by their sexual rudiments. Copulation takes place immediately upon emergence of the females between siblings, adult males appearing before the females. Females in culture with access to an energy source can survive for more than 60 days. They are synovigenic: they emerge with no mature eggs in their ovaries and take the first two days after emergence to mature the full set of around 24-30 eggs. They continue paralyzing hosts, ovipositing and maturing eggs for as long as they live. After an oviposition a female needs two to three days to mature a new full set of eggs. Age and feeding influence egg load. OÜsorption is significant in starved females, but also occurs in older fed females with no host contact.
Highlights
The reproductive success of many hymenopterous parasitoids is influenced by supplemental feeding
Most studies of the effects of adult feeding on lifetime reproductive success have shown that, for host-feeding species, sugar meals increase longevity, while host-feeding provides materials used for egg maturation
Reproductive biology Two-way ANOVA shows that egg load is significantly influenced by age (F = 22.42, df = 4,152, P < 0.0001) and by feeding (F = 202.51, df = 1,152, P < 0.0001)
Summary
The reproductive success of many hymenopterous parasitoids is influenced by supplemental feeding (reviewed by Thompson, 1999). Though, can have a direct influence on the number of mature eggs a female carries, as for example in species with oosorption (Edwards, 1954) and in species that have to feed first after eclosion, in order to mature their eggs (Mao & Kunimi, 1994). Knowledge of these factors is important, as they may influence the success of an antagonist released as a biological measure in the field
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