Chemical Ecology of Host- and Mate-Finding in the Cypress Bark Beetle Phloeosinus aubei, with Notes on Congeneric Species

TL;DR

This paper reviews the chemical signals used by the cypress bark beetle to find hosts and mates, aiming to develop traps for pest control.

Contribution

The paper provides a detailed overview of the chemical communication system of Phloeosinus aubei and its congeneric species.

Findings

Host selection by females relies on kairomones from host plants.

Aggregation pheromones attract conspecifics and are reinforced during mass colonization.

An inhibitory signal limits population density to prevent over-colonization.

Abstract

The Mediterranean cypress bark beetle (CBB), Phloeosinus aubei, is a serious xylophagous pest of scale-leaved conifers of the Cupressaceae family. Its increasing silvicultural importance and accelerated spread, favored by climate change and driven by international timber trade, has brought it into the focus of chemoecological research. The latest investigations on host plant volatiles and intraspecific signaling have paved the way for the development of attractant traps for monitoring and mass trapping. In this review, we provide insight into the complex chemical communication system of P. aubei. First, host selection by the females occurs using kairomones. Then aggregation pheromones attract more conspecifics, initially produced by the pioneering females and reinforced by both sexes as mass colonization ensues. Finally, an inhibitory signal is emitted to limit population density.

Recent intensive research on the cypress bark beetle, Phloeosinus aubei was prompted because of its invasion of Central Europe that caused serious damage to scale-leaved conifer ornamental trees. This dynamic also increased the risk of accidental introduction into North America. In contrast to other historically well-studied bark beetles infesting spruce, pine or broad-leaf trees, intense study of the pheromones and host plant kairomones of bark beetles associated with cupressaceous trees has only begun in the past decade. This highly specialized clade is represented by the genus Phloeosinus. The pressing need for semiochemical-baited traps demands the identification of behavior-modifying compounds. This challenge involves unraveling the various stimuli interacting in the complex communication system to reveal the composition of signal bouquets and the absolute configuration of their components capable of evoking behavior responses. In this short overview we describe the recent research results on host-finding and intraspecific chemical communication of P. aubei, with a short outlook on the species of this genus.

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