Competitive interactions between the mountain pine beetle and the pine engraver in lodgepole pine

Abstract

The pine engraver (PE), Ipspini (Say), often coexists with the mountain pine beetle (MPB), Dendroctonusponderosae Hopk., in lodgepole pine, Pinuscontorta var. latifolia Engelm. The PE colonizes the upper bole, while the MPB infests the lower bole. We investigated the hypothesis that interspecific interactions between the PE and the MPB within trees can adversely affect MPB progeny production or survival. In lodgepole pine bark attacked by both species, PE and MPB emergence holes had a strong negative interrelationship, suggesting that high numbers of one species resulted in lower numbers of the other. In the laboratory, attacks by PEs on lodgepole pine logs resulted in significantly decreased numbers of MPB progeny, particularly when MPBs and PEs were allowed to attack logs simultaneously. Reductions in MPB progeny were 92.8 and 96.2% when the ratios of attacking beetles were 100 PE: 50 MPB per square metre and 200 PE: 50 MPB per square metre, respectively, compared with that in control logs with 50 MPB per square metre. In an August field experiment, pheromone-induced attack by the PE on trees just attacked by the MPB resulted in a 72.5% reduction in mean MPB progeny production compared with that in MPB-attacked control trees. Possible reasons for the reduced success of MPB when it and the PE coinhabit the same host may be exploitation competition, interference competition, or introduction of fungal competitors deleterious to the MPB. Induced infestation by PEs of MPB-infested trees may have the potential to reduce or control MPB populations.

Ecological segregation of bark beetle (Coleoptera, Curculionidae, Scolytinae) infested Scots pine

“…This may indicate a low degree of competitive interaction for living space among individuals of the coexisting species (Colvell and Futuyma 1971;Ratchke 1976;Lawlor 1980). The model developed by Price (1997) used for the description of tree infestation patterns shows a positive correlation between the body size of a beetle with the thickness of the phloem and area of the exploited resources. The presented relationships partly confirm the results of the studies carried out in the trap trees.…”

Dynamics of pheromone production and communication in the mountain pine beetle, Dendroctonus ponderosae Hopkins, and the pine engraver, Ips pini (Say) (Coleoptera: Scolytidae)

“…conspecific females (Otte 1972;Thomhill 1983). Satellite males are common in many insect groups in which aggregations are purely a consequence of a communication system intended to attract females to signalling males (Thomhill 1983), especially when aggregation on a scarce resource is of questionable benefit to pheromone producing males (Robins and Reid 1997), as it results in offspring of inferior quality (Rankin and Borden 1991).…”

New repellent semiochemicals for three species of Dendroctonus (Coleoptera: Scolytidae)

“…Interspecific interactions among coniferophagous bark beetles (Coleoptera: Scolytidae) are common when two or more species attack and colonise the same host (Byers & Wood 1980, Svihra et al 1980Rankin & Borden 1991;Byers 1993;Schlyter & Anderbrant 1993;Poland & Borden 1998a, b, c;Ayres et al 2001). Beetles may be attracted to semiochemicals emitted by heterospecifics and apparently use them to locate hosts which may be rare or patchy in distribution (Byers & Wood 1981;Poland & Borden 1994;Savoie et al 1998;Ayres et al 2001).…”

“…Alternatively, they may be repelled, a response that would facilitate resource partitioning, decrease interspecific competition (Byers & Wood 1980Byers et al 1984;Borden et al 1992;Poland & Borden 1998a,b,c;Pureswaran et al 2000;Ayres et al 2001), and maximise survival of brood. While several studies document the perception and deterrence of bark beetles to semiochemicals emitted by heterospecifics inhabiting the same host species (Byers & Wood 1980;Svihra et al 1980;Light et al 1983;Rankin & Borden 1991;Borden et al 1992;Byers 1993;Poland & Borden 1998a, b, c;Savoie et al 1998;Pureswaran et al 2000;Ayres et al 2001), no studies have investigated whether bark beetles can perceive and avoid semiochemicals produced by heterospecifics that attack nonhost conifers. Pureswaran et al (2004) used gas chromatographicelectroantennographic detection analyses (GC-EAD) and GC-mass spectrometry (GC-MS) to survey the production and perception profiles of semiochemicals in four sympatric species of tree-killing bark beetles, three Dendroctonus spp.…”