Categorizing experience-based foraging plasticity in mites: age dependency, primacy effects and memory persistence.

Peter Schausberger,Stéphanie Saussure,Undarmaa Davaasambuu,Inga C Christiansen

doi:10.1098/rsos.172110

Abstract

Behavioural plasticity can be categorized into activational (also termed contextual) and developmental plasticity. Activational plasticity allows immediate contextual behavioural changes, whereas developmental plasticity is characterized by time-lagged changes based on memory of previous experiences (learning). Behavioural plasticity tends to decline with age but whether this holds true for both plasticity categories and the effects of first-in-life experiences is poorly understood. We tackled this issue by assessing the foraging plasticity of plant-inhabiting predatory mites, Amblyseius swirskii, on thrips and spider mites following age-dependent prey experience, i.e. after hatching or after reaching maturity. Juvenile and young adult predator females were alternately presented thrips and spider mites, for establishing 1st and 2nd prey-in-life experiences, and tested, as gravid females, for their foraging plasticity when offered both prey species. Prey experience by juvenile predators resulted in clear learning effects, which were evident in likelier and earlier attacks on familiar prey, and higher proportional inclusion of familiar prey in total diet. First prey-in-life experience by juvenile but not adult predators resulted in primacy effects regarding attack latency. Prey experience by adult predators resulted mainly in prey-unspecific physiological changes, with easy-to-grasp spider mites providing higher net energy gains than difficult-to-grasp thrips. Prey experience by juvenile, but not adult, predators was adaptive, which was evident in a negative correlation between attack latencies and egg production. Overall, our study provides key evidence that similar experiences by juvenile and adult predators, including first-in-life experiences, may be associated with different types of behavioural plasticity, i.e. developmental and activational plasticity.

Highlights

Phenotypic plasticity of behaviour, i.e. the ability of the same genotype to flexibly express or develop a given behaviour, allows animals to adaptively cope with environmental variation and/or novelty [1,2,3,4,5]
Owing to thrips intrinsically being a more difficult-to-get prey for prey-naive predators than spider mites, learning the cues of thrips entails a greater potential for A. swirskii to enhance foraging than learning the cues of spider mites [19,20]
In experiment 2, use of prey-naive individuals—prey-naive because of exclusive rearing on pollen during juvenile development—excludes that any observed behavioural plasticity represents an epiphenomenon of prey experience-based plasticity developed in the juvenile phase [5,8]

Summary

Introduction

Phenotypic plasticity of behaviour, i.e. the ability of the same genotype to flexibly express or develop a given behaviour, allows animals to adaptively cope with environmental variation and/or novelty [1,2,3,4,5]. Behavioural plasticity may be categorized into activational ( termed contextual) and developmental plasticity [3,5]. Developmental plasticity of behaviour is typically dubbed learning, i.e. behavioural change based on experience. The reason is that behavioural plasticity expressed in advanced life phases may be the result, or an epiphenomenon, of developmental plasticity, i.e. learning, early in life Categorizing activational and developmental plasticity inevitably requires knowing about the developmental and rearing history of the experimental animals and their experiences

Methods

Results

Conclusion