Chemical Ecology of Capnodis tenebrionis (L.) (Coleoptera: Buprestidae): Behavioral and Biochemical Strategies for Intraspecific and Host Interactions.

Giuseppe Bari,Heiko Vogel,Enrico De Lillo,Antonella Maria Aresta,Vita Garzone,Pasqua Vernile,Osvaldo Facini,Rosanna Salvia,Patrizia Falabella,Andrea Scala,Francesca Rapparini,Sabino A Bufo,Cem Yalcin,Rita Baraldi

doi:10.3389/fphys.2019.00604

Abstract

This study focuses on several aspects of communication strategies adopted by adults of the Mediterranean flat-headed root-borer Capnodis tenebrionis (Coleoptera: Buprestidae). Morphological studies on the structures involved in mate recognition and acceptance revealed the presence of porous areas in the pronota in both sexes. These areas were variable in shape and size, but proportionally larger in males. The presence of chaetic, basiconic, and coeloconic sensilla in the antennae of both males and females was verified. Bioassays revealed stereotyped rituals in males and the involvement of female pronotal secretions in mate recognition and acceptance. During the mating assays, the female’s pronotum was covered by a biologically inert polymeric resin (DenFilTM), which prevented males from detecting the secretions and from completing the copulation ritual. The use of the resin allowed for the collection of chemical compounds. GC-MS analysis of the resin suggested it may be used to retain compounds from insect body surfaces and revealed sex-specific chemical profiles in the cuticles. Since adult C. tenebrionis may use volatile organic compounds (VOCs) emitted from leaves or shoots, the VOC emission profiles of apricot trees were characterized. Several volatiles related to plant-insect interactions involving fruit tree species of the Rosaceae family and buprestid beetles were identified. To improve understanding of how VOCs are perceived, candidate soluble olfactory proteins involved in chemoreception (odorant-binding proteins and chemosensory proteins) were identified using tissue and sex-specific RNA-seq data. The implications for chemical identification, physiological and ecological functions in intraspecific communication and insect–host interactions are discussed and potential applications for monitoring presented.

Highlights

Capnodis tenebrionis (L.) (Coleoptera: Buprestidae), commonly known as the Mediterranean flat-headed root-borer, affects many species of Rosaceae, apricot, peach, plum, nectarine, cherry, and almond (Malagon et al, 1990; Ben-Yehuda et al, 2000; Marannino and de Lillo, 2007; Morton and García del Pino, 2008)
The pore arrangement was not perfectly symmetrical and porous fields were larger in males than in females when the surfaces of whole pronotum were compared
Gland pores were previously detected on pronota of other male Coleoptera, including many long-horned beetles, and in some species were related to sex or aggregation pheromone secretions (Noldt et al, 1995; Ray et al, 2006; Hanks et al, 2007; Lacey et al, 2007; Hanks and Millar, 2016)

Summary

Introduction

Capnodis tenebrionis (L.) (Coleoptera: Buprestidae), commonly known as the Mediterranean flat-headed root-borer, affects many species of Rosaceae, apricot, peach, plum, nectarine, cherry, and almond (Malagon et al, 1990; Ben-Yehuda et al, 2000; Marannino and de Lillo, 2007; Morton and García del Pino, 2008). Adult beetles feed on the bark of shoots, buds, and leaf petioles, and usually prefer weakened and diseased trees rather than vigorous ones (Rivnay, 1946; Garrido, 1984; Bonsignore and Bellamy, 2007). These adults can seriously damage young trees in nurseries, orchards and greenhouses, but rarely affect established, well-cultivated and irrigated fruit-bearing orchards (García del Pino and Morton, 2005). One-year-old trees can be killed by a single larva; a few larvae can lead to the death of a mature tree within 1 or 2 years (Ben-Yehuda et al, 2000; García del Pino and Morton, 2005)

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Results

Conclusion