Abstract
Two sibling weevil species, Pissodes strobi Peck and P. nemorensis Germar (Coleoptera: Curculionidae), can form reduced-fitness hybrids in the laboratory, but neither their premating isolation mechanisms nor mating behaviors are well-understood. Cuticular hydrocarbons (CHCs) have been reported as crucial chemical cues in mating recognition in many insects, including weevils, and, thus, may also mediate the mating behavior of P. strobi and P. nemorensis. We conducted a series of behavioral observations, bioassays, and chemical analyses to investigate the role of CHCs in their mating behavior. Copulation behavior of both species followed similar steps: approaching, mounting, tapping, aedeagus extrusion, and copulation. In P. strobi, hexane extraction significantly reduced the number of successful male copulations compared with freeze-killed females. Conversely, significantly fewer P. nemorensis males copulated with dead females compared with live females. No significant differences were detected among hexane-extracted, freeze-killed or recoated female carcasses to P. nemorensis. These findings suggested that female cuticular extracts contain important cues in mate recognition in P. strobi but not in P. nemorensis. We identified 21 CHCs from both species with variation in abundances between sexes and seasons. Discriminant analysis revealed incomplete overlap of CHC compositions in females of the two species in summer, when hybridization potentially occurs.
Highlights
Cuticular hydrocarbons (CHCs) are nonvolatile long-chain hydrocarbons that protect insects from desiccation, pathogens, and mechanical damage [1]
P. strobi adults were collected from white pine, Pinus strobus, leaders near Star Lake (44.167551, −75.048181), NY, USA, and P. nemorensis adults were collected from fallen red pine, Pinus resinosa, in the Svend O
The mating behavior patterns we observed in P. strobi and P. nemorensis were similar to those observed in other curculionids
Summary
Cuticular hydrocarbons (CHCs) are nonvolatile long-chain hydrocarbons that protect insects from desiccation, pathogens, and mechanical damage [1] They have an important role in insect chemical communication, such as mate recognition and stimulating copulation [2]. Pissodes strobi Peck and Pissodes nemorensis Germar (Coleoptera: Curculionidae) are sibling species that damage a range of Pinus and Picea species in North America with one generation per year [19,20,21]. These two weevil species are morphologically similar and can mate, resulting in hybrid offspring [21,22,23]. Feed and oviposit on leaders, whereas P. nemorensis feed and oviposit on slash and the lower stems
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