Host preference and offspring performance are linked in three congeneric hyperparasitoid species

Abstract

International audience1. The optimisation theory predicts that insect mothers should oviposit on resources on which they attain the highest exclusive fitness. The development of parasitoid wasps is dependent on limited host resources that are often not much larger than the adult parasitoid.2. In the present study preference and development in three congeneric species of secondary hyperparasitoids attacking cocoons of two congeneric primary parasitoids that differ significantly in size were compared. Gelis agilis (Fabricius) and G. acarorum (L.) are wingless hyperparasitoids that forage in grassy habitats, whereas G. areator (Panzer) is fully winged and forages higher in the canopy of forbs.3. The three species were reared on cocoons containing pupae of a small gregarious endoparasitoid, Cotesia glomerata (L.), and a larger solitary species, C. rubecula (Marshall), both of which develop in the caterpillars of pierid butterflies.4. Adult mass was correlated with initial cocoon mass in all three species, whereas development time was unaffected. Wasps were larger when developing in C. rubecula. However, for a given host mass, wasps were larger when developing on the smaller host, C. glomerata. This suggests that there is a physiological limit to hyperparasitoid size that was exceeded when C. rubecula served as host.5. All three hyperparasitoids strongly preferred to attack cocoons of the larger species, C. rubecula, often avoiding cocoons of C. glomerata entirely. 6. Preference and performance are correlated in the three Gelis species. However, owing to variation in the distribution and thus abundance of their hosts, it is argued that cumulative fitness may be still higher in the smaller host species

Spatial and temporal diversity in hyperparasitoid communities of Cotesia glomerata on garlic mustard, Alliaria petiolata

“…By contrast, wingless species clearly cannot traverse very large distances (as they do not possess wings), but they can easily navigate more dense vegetation and leaf litter, where many Gelis species are often found (Harvey et al, , 2015. Similar to the previous study, we noted that the wingless species of the genus Gelis are mainly found in the clusters near the ground, whereas the winged species, such as G. aereator and A. nens, are mostly found in the canopy.…”

“…Having wings, however, comes with a trade-off, as flying is likely to be more difficult in dense undergrowth, leaving an entire area relatively unexplored. By contrast, wingless species clearly cannot traverse very large distances (as they do not possess wings), but they can easily navigate more dense vegetation and leaf litter, where many Gelis species are often found (Harvey et al, , 2015. What is interesting is that the composition of the communities differed quite substantially from the previous study.…”

“…Previous studies have shown that some species of the Gelis genus have life spans of 70 days without hosts at ambient temperatures (Harvey, 2008;Harvey et al, 2015Harvey et al, , 2017Visser et al, 2016). Around this time, it is rare to see a cabbage white butterfly adult, let alone their larvae.…”

“…This raises the question as to where these early hyperparasitoids come from and why they are already active during times when their hosts are not yet present. Previous studies have shown that some species of the Gelis genus have life spans of 70 days without hosts at ambient temperatures (Harvey, 2008;Harvey et al, 2015Harvey et al, , 2017Visser et al, 2016). As metabolic rates generally decrease with falling temperatures, it is expected that life span could be even higher under colder temperature regimes, so it could be that these species overwinter during the adult stage and oviposit at the first opportunity that is presented.…”

The roles of foraging environment, host species, and host diet for a generalist pupal parasitoid

“…Most parasitoids use multiple host species, preferring and performing better on one over another (Ode, 2006;Harvey et al, 2015). We found that a larger fraction of M. cinxia than of M. athalia that were placed in the field became parasitised, suggesting that the M. cinxia is the preferred or more accessible host.…”