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Research article - Peer-reviewed, 2015

How far away is the next basket of eggs? Spatial memory and perceived cues shape aggregation patterns in a leaf beetle

Stephan, Jörg; Stenberg, Johan A.; Björkman, Christer

Abstract

Gregarious organisms need to handle the trade-off between increasing food competition and the positive effects of group living, and this is particularly important for ovipositing females. We hypothesized that insect females consider how many conspecifics previously visited a host plant. In a no-choice assay, we show that the gregarious blue willow leaf beetle (Phratora vulgatissima) laid the most eggs and the largest clutches on plants where a sequence of few individual females was released, compared to plants where one or many different females were repeatedly released. Therefore, this species is more sensitive to the indirectly perceived number of conspecifics than the directly perceived number of eggs on a plant. We further hypothesized that females adjust their own intra-plant egg clutch distribution to that of conspecifics and discovered a new behavioral component, i.e., the modulation of distances between clutches. Females adjusted these distances in ways indicating the use of spatial memory, because the largest distance increases were observed on plants with their own clutches, compared to plants with clutches from conspecifics. However, adjustment of aggregation level and distance between clutches occurred only on a suitable, and not on an unsuitable, Salix genotype. We conclude that both behaviors should reduce competition between sibling and non-sibling larvae.

Keywords

blue willow leaf beetle, Phratora vulgatissima; clutch size; cognitive map; Coleoptera; density; distance; egg pooling; kin recognition; learning; relatedness; Salix

Published in

Ecology
2015, volume: 96, number: 4, pages: 908-914
Publisher: ECOLOGICAL SOC AMER

Authors' information

Swedish University of Agricultural Sciences, Department of Ecology
Stenberg, Johan A. (Stenberg, Johan A)
Swedish University of Agricultural Sciences, Department of Plant Protection Biology
Swedish University of Agricultural Sciences, Department of Ecology

Associated SLU-program

SLU Future Forests

UKÄ Subject classification

Ecology

Publication Identifiers

DOI: https://doi.org/10.1890/14-1143.1.sm

URI (permanent link to this page)

https://res.slu.se/id/publ/67126