Clutch size decisions of Cotesia glomerata, a gregarious parasitoid of Pieris brassicae

Abstract

This work investigated the ability of the gregarious larval endoparasitoid Cotesia glomerata L. (Hymenoptera: Braconidae) to adjust the progeny sex ratio and clutch size with repeated oviposition experience and the effect of a honey-based diet on the clutch size. In the field-collected clusters many clusters were female-biased but some clusters (3.8%) produced only male wasps, suggesting that there is a low percentage of unmated females in the field. Superparasitism was common in the field, and females were believed to increase progeny sex ratio when attacking previously parasitized hosts. In the laboratory, the number of eggs laid in a day tended to decrease with increasing female age. For females that were offered two hosts per day and for those offered three hosts per day, this value became nearly the same at 9 days after the start of oviposition. Old females which attacked many hosts tended to lay fewer eggs in a day than young ones. However, the degree of this tendency was not the same for all the parasitoid females of all three groups because sperm remained viable throughout a female's lifetime. The amount of sperm used in a single oviposition bout seemed fixed and was not dependent on the number of eggs laid. Over the 2 days of the clutch size response experiment, the number of hosts a female attacked per day was not affected by the presence or absence of honey.

Experience‐ and age‐mediated oviposition behaviour in the yellow fever mosquito Stegomyia aegypti (=Aedes aegypti)

“…Older individuals did, however, lay significantly fewer eggs than younger mosquitoes ( P = 0.017), which may be a strategy to reduce maternal mortality by resorbing eggs with age, as has been shown previously in an ectoparasitoid (Giron & Casas, ). Reduced egg loads in older adults may also be a physiological consequence of the gradual depletion of nutrients necessary for egg production (Begon & Parker, ), which has been shown in other insects (Elzinga et al , ; Hasan & Ansari, ).…”

Facultative gregarious development in a solitary koinobiont parasitoid, Ephedrus californicus: implications of larval ecology and host constraints

“…The two lifestyles differ in the manner in which larvae respond to superparasitism, that is, the presence in the host of more parasitoid offspring than can complete development to the adult stage. In gregarious species, the larvae are tolerant of potential competitors; survival and final clutch size are determined by scramble competition for resources during late larval development (Salt, 1961; Harvey et al., 1998; Dorn & Beckage, 2007; Hasan & Ansari, 2010). In solitary species, in contrast, first instars behave aggressively towards potential competitors including siblings, with survival being determined by fighting; only one larva completes development per host (Salt, 1961; Mackauer, 1990; Roberts et al., 2004; Chau & Maeto, 2008).…”

Australian native flowering plants enhance the longevity of three parasitoids of brassica pests

“…This important finding has important implications for their effects on biological control in adjacent crops. Literature shows that increased reproductive lifespan enhances fecundity as well as host parasitism in general (Heimpel & Jervis, 2005;Benelli et al, 2017) as well as specifically for D. rapae (Tylianakis et al, 2004;Jamont et al, 2013), D. semiclausum (Yang et al, 1993;Winkler et al, 2006), and C. glomerata (Hasan & Ansari, 2010). The extent of longevity benefit to parasitoids varied depending on the flower species and interplay between flower species and parasitoid species.…”