Understanding the mismatch between behaviour and development in a novel host-parasitoid association

Joanna K. Konopka,Tara Gariepy,Danny Poinapen,Jeremy N. McNeil

doi:10.1038/s41598-018-33756-6

Joanna K. Konopka, Tara Gariepy + Show 2 more

Open Access

https://doi.org/10.1038/s41598-018-33756-6

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Abstract

Foraging parasitoid females should preferentially oviposit on hosts most suitable for progeny development to maximize their fitness. However, the introduction of a new host species may disrupt the link between the reliability of the cues and the expected adaptive outcome of female choice, leading to an evolutionary trap. This mismatch between behavioural acceptance and lack of development exists for North American and European egg parasitoids (Scelionidae) that encounter invasive Halyomorpha halys in areas where this exotic host has recently established. To explain this mismatch, we utilized an L9 orthogonal array design to assess and rank the influence of several critical factors characterizing host resource (host species, egg age, egg status, and surface wash) on behaviour (acceptance, patch residence and patch exploitation) and development of North American native Trissolcus euschisti egg parasitoid. Our results indicate that the host egg age is most important for behaviour, but is least influential for development of the progeny. This study suggests that the maladaptive decision to oviposit in an unsuitable host is due to a mismatch between the cues that females use, and the subsequent expected outcome of this choice. Therefore, it is the relative importance of individual factors when assessed simultaneously that influences the decision-making of female parasitoids.

Highlights

The preference-performance hypothesis postulates that female insects will oviposit in or on hosts most suitable for their offspring’s development[1]
Trissolcus euschisti females accepted H. halys and E. variolarius egg masses washed in acetone (Experiments 5 and 9 respectively), significantly less often as oviposition sites (53% and 40% respectively) (χ2 (8, N= 135) = 56.84, p < 0.001) than all other egg masses, including the control (Experiment 3; freshly laid non washed P. maculiventris eggs) (Fig. 1)
The majority of time spent on an egg mass was allocated to oviposition, and the remainder to unsuccessful parasitization attempts and surface antennation

Summary

Introduction

The preference-performance hypothesis postulates that female insects will oviposit in or on hosts most suitable for their offspring’s development[1]. At any step in this behavioural sequence, the female’s decision will be influenced by several factors These factors include the female’s biological and physiological state (e.g. age, egg load, nutritional or mating status, previous oviposition experience), or the perceived quality of the egg mass or individual eggs within the mass (e.g. age, size, shape, chemical cues, parasitized state or presence of a competitor)[18,19,20,21,22,23]. No clear explanation or mechanism has been proposed for this mismatch between behavioural acceptance by these females and lack of larval development, even though significant efforts are being made to characterize and understand the impact H. halys has on the native parasitoid communities following its introduction[32]

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