Enantiospecific responses of southern pine beetle (Dendroctonus frontalis) and its clerid predator, Thanasimus dubius, to α-pinene

Abstract

Multi-trophic interactions between pine bark beetles, their host trees, and predators are mediated in part by volatile terpenes in host tree oleoresin that can influence aggregation and/or host finding by both prey and predator species. The southern pine beetle, Dendroctonus frontalis Zimmermann, mass-attacks pine trees in response to its aggregation pheromone combined with host resin odors including a-pinene. We investigated discrimination of apinene enantiomers in olfactory responses of D. frontalis, and in behavioral responses of D. frontalis and its major clerid predator, Thanasimus dubius (Fabricius). Trapping trials in the spring and fall assessed attraction of both species to the D. frontalis aggregation pheromone components, frontalin and endo-brevicomin, either alone or in combination with a-pinene lures of differing enantiomeric compositions. a-Pinene lures enriched with the (?)-enantiomer (97.5 %) increased D. frontalis catches significantly more than (-)-enriched (93 %) lures, but did not differ from racemic lures. Sexes of D. frontalis did not differ from one another in their responses to the enantiomers, and there was no difference in lure discrimination by D. frontalis and T. dubius. Thanasimus dubius did not distinguish between different a-pinene enantiomers. Dose-response electroantennogram studies of D. frontalis indicated that their antennae had a slightly lower response threshold to (?) than (-)-a-pinene. Each enantiomer habituated the antennae more to itself than to its antipode, implying the existence of olfactory receptors with differing affinities for enantiomers. The preference of D. frontalis for (?)-apinene may affect its host selection behavior, and should be considered in population monitoring lures.

EAG response and behavioral orientation of Dastarcus helophoroides (Fairmaire) (Coleoptera: Bothrideridae) to synthetic host-associated volatiles

“…The prey-associated plant volatiles played a crucial role in the prey location process of D . helophoroides , as demonstrated in another coleopteran predator Thanasimus dubius for the forest pest Dendroctonus frontalis [ 29 ] . D .…”

Semiochemicals in the Natural History of Southern Pine Beetle Dendroctonus frontalis Zimmermann and Their Role in Pest Management

“…(Mirov, 1961). The (+)-enantiomer of α-pinene is a better synergist than the (À)-enantiomer, and EAG cross-adaptation studies indicated that both sexes possess at least some receptors with differing affinities for the two enantiomers (Staeben et al, 2015). The antennae also have a lower response threshold to (+) than (À)-α-pinene.…”

“…Thanasimus dubius apparently locate D. frontalis-attacked trees primarily by responding to frontalin and host monoterpenes (Vit e and Williamson, 1970). In experimental trials the host component could be presented as either α-pinene or distilled pine resin (Billings, 1985;Billings and Cameron, 1984;Costa and Reeve, 2011;Staeben et al, 2015;Vit e and Williamson, 1970). Thanasimus dubius may sometimes be observed congregating on pines where D. frontalis brood beetles are emerging (Clarke and Menard, 2006), presumably because the emergent D. frontalis contain their aggregation pheromone (Pureswaran et al, 2007) and are apparently "leaking" it in sufficient quantities during emergence to attract this predator.…”

“…As such, its presence might not increase the odds of a T. dubius encountering a prey insect at least at close range. A mismatch of attractive cues also occurs due to a preference by D. frontalis for the (+)-enantiomer of the synergistic host monoterpene α-pinene when combined with its aggregation pheromone, whereas no preference for enantiomers occurs in T. dubius (Staeben et al, 2015). As the host species of pine utilized by D. frontalis vary in the enantiomeric composition of α-pinene, presumably D. frontalis might enhance escape from predation in preferential attack of trees with relatively high (+)-α-pinene composition, such as Pinus taeda L. which is a preferred host for D. frontalis (Phillips et al, 1999).…”

How to fight against southern pine beetle epidemics: An insurance approach

“…Scholars from different scientific backgrounds have done extensive research on infestation, spread, and outbreak patterns of SPB. Biologists (Hofstetter, Cronin, Klepzig, Moser, & Ayres, 2006;Vasanthakumar et al, 2006) have studied the individual SPB infestation behavior, while forest entomologists (Fargo, Coulson, Pulley, Pope, & Kelley, 1978;Staeben, Sullivan, Nowak, & Gandhi, 2015;Strom, Meeker, Bishir, Roberds, & Wan, 2016) have studied the SPB outbreaks at the stand scale. In addition, SPB outbreaks across tree stands and at the landscape level have been evaluated (Niemiec, Lutz, & Howarth, 2014;Nowak, Meeker, Coyle, Steiner, & Brownie, 2015).…”