Primary attraction and random landing in host‐selection by wood‐feeding insects: a matter of scale?

Abstract

1 Most plant-feeding insects show some degree of specialization and use a variety of cues to locate their host. Two main mechanisms of host location, primary attraction and random landing, have been investigated for such insects. 2 Research has led to contradictory conclusions about those hypotheses, especially for wood-feeding insects; however, recent studies suggest that both mechanisms may take place in a single taxon but at different scales. 3 We developed a field experiment to test the hypothesis that primary attraction occurs at larger scale and random landing at finer scale in wood-feeding insects.Landing rates, measured using sticky traps, were compared first between patches and then between individual trees according to their distance to a baited central tree. 4 Polynomial functions describing landing rate to distance relationships were compared with a function produced by a null model describing what should occur under the random landing hypothesis. Scolytidae and Cerambycidae (Coleoptera) responded to volatiles at the patch scale, supporting the primary attraction hypothesis, but the landing patterns of some groups at finer scale matched closely the predictions of our null model, giving support to the random landing hypothesis. 5 Our results show that the primary attraction and random landing hypotheses are not mutually exclusive and that prelanding use of host-produced volatile is scaledependant. Scale considerations should thus be included in the study of prelanding host-selection of wood-feeding insects.

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

“…Alternatively, beetles may select a host by means of close-range olfactory, gustatory, or other contact cues following random landing on the bark surface. These beetles land presumably in response to the host's dark vertical silhouette and evaluate each tree before attempting to initiate a mine; they resume flight if the tree is found to be unsuitable (Byers, 1996;Hynum and Berryman, 1980;Moeck, 1978;Moeck et al, 1981;Saint-Germain et al, 2007). Evidence that beetles follow this "random landing" strategy include that (1) in some instances landing frequency by dispersing beetles on potential host trees is uncorrelated to subsequent attacks or is not stimulated by artificial treatments inducing host susceptibility (Hynum and Berryman, 1980;Moeck et al, 1981;Raffa and Berryman, 1980), and (2) models which indicate that, although long-range identification of suitable host trees by primary cues may be a more efficient host selection strategy, random landing is a sufficient means for host location by pioneers (Byers, 1996;Gries et al, 1989).…”

Phylogenetic Relationships of the Genus Chamaecyparis Inferred from Leaf Essential Oil

“…It acts as a semiochemical, playing an important role in recruiting coccinellid natural enemies of the scale insects [37]. Ethanol and a-pinene have been shown to act as attractants to a large number of wood-feeding species and often act synergistically [38] [39].…”

Post-fire attractiveness of maritime pines (Pinus pinaster Ait.) to xylophagous insects

“…Host selection mechanisms by bark beetles are fundamentally olfactory and visual, driven by plant size, shape, colour and volatile compounds (Bernays and Chapman 1994;Brattli et al 1998;Mustaparta 2002;Saint-Germain et al 2007a;Campbell and Borden 2009). Several species of wood-feeding insects almost exclusively prefer trees that are heavily stressed or have been recently killed by fire, fungal diseases, defoliating insects or harvesting operations, taking advantage of the weakened defence system of the host plant (Christiansen et al 1987;Paine et al 1997;Dajoz 2000;Parker et al 2006).…”