Ontogenetic shift in plant-related cognitive specialization by the mosquito-eating jumping spider, Evarcha culicivora

Abstract

The East African jumping spider, Evarcha culicivora, preferentially feeds on Anopheles mosquitoes. This spider carries out apparently complex cognitive processes, namely, cross-modal selective attention, to detect and locate this specific prey. Juvenile E. culicivora supplement their diet with nectar, primarily from Lantana camara, and the sugar from these nectar meals makes them more proficient at capturing their preferred prey. Both the adult and the juvenile spiders are attracted to the odour of L.camara among other plants. Here, I test the effects of plant odours on adult and juvenile spiders’ response to visual stimuli, in order to elucidate the function of E. culicivora’s response to plant odours across the spider’s lifetime. I found that, for juveniles, plant odours elicit selective attention to a visual stimulus consisting of L.camara flowers, consistent with previous research showing plants are important to juveniles in the context of nectar feeding. For adults, I found that plant odours elicit selective attention to a visual mate stimulus, in much the same way that mate odour did. Specifically, adult spiders responded strongly to a visual stimulus consisting of mates in conjunction with plants after exposure to plant odour. I discuss the implications of these findings with regards to the representation of the plant stimulus in the spider’s miniature brain. I propose a model in which the cognitive process triggered by the plant odour stimulus changes between the juvenile and adult life stages. I conclude with the suggestion that spiders use highly specialized representations of salient stimuli to perform apparently complex cognitive tasks. Moreover, my results show that these representations change between these life stages.