Abstract
Parasitoid host selection behaviour has been extensively studied in experimentally simplified tritrophic systems formed by one single food chain (one plant, one herbivore and one parasitoid species). The "Mother knows best" hypothesis predicts that the preference for a plant-host complex should be positively correlated with plant quality for offspring performance. We studied the host selection behaviour of the generalist endoparasitoid Aphidius matricariae towards the black bean aphid Aphis fabae in the intercrop system including Vicia faba as a focal plant and its companion plant Camelina sativa. Dual-choice laboratory bioassays revealed that parasitoid females preferred to orientate towards (1) the plant-aphid complex over the non-infested plant whatever the complex (2) the C. sativa-A. fabae complex over the V. faba-A. fabae complex. In dual choice attack rate bioassays, parasitoid females showed more interest towards the aphids on C. sativa but paradoxically chose to oviposit more in aphids on V. faba. Ultimately, parasitoids that had developed on the V. faba-A. fabae complex exhibited better fitness parameters. By demonstrating that parasitoid females were able to discriminate the aphid host that offered the highest fitness to their offspring but selected beforehand the least suitable plant-aphid complex, we provide key insight into the disruption in their host selection behaviour potentially triggered by diverse habitats. This suggests that the "Mother knows best" hypothesis could be thwarted by increasing the complexity of the studied systems.
Highlights
The "Mother knows best" hypothesis, known as the "preference-performance hypothesis", derives from the general optimality theory originally set for phytophagous insects [1,2,3,4], which states that female oviposition preferences should positively correlate with host suitability for offspring development
In the presence of both infested plants, A. matricariae females exhibited a significant preference for the C. sativa-A. fabae complex (χ2-test, χ2 = 4.737, P = 0.029; S4 Table)
The number of Antennal Examination, Abdomen Bending and Ovipositor Insertion was significantly greater on A. fabae on C. sativa
Summary
The "Mother knows best" hypothesis, known as the "preference-performance hypothesis", derives from the general optimality theory originally set for phytophagous insects [1,2,3,4], which states that female oviposition preferences should positively correlate with host suitability for offspring development (i.e. offspring survival and further adult fecundity). The "Mother knows best" hypothesis has been recently expanded to parasitoid insects [5], natural enemies of phytophagous insects. Because their larvae develop as obligatory parasites, the reproductive success. Parasitoid Host Selection in a Complex Habitat
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