Respuesta de insectos descortezadores de pino y de sus depredadores a semioquímicos en el sur de México

Se documenta la atracción en campo de insectos descortezadores (Coleoptera: Curculionidae, scolytinae) de pino y sus depredadores, a trampas multiembudos cebadas con formulaciones comerciales que contenían una de tres combinaciones de a-pineno con frontalina, ipsenol o con ipsdienol en el sur de México. El descortezador Dendroctonus frontalis Zimmermann fue atraído únicamente a frontalina + a-pineno. El descortezador Ips grandicollis (Eichhoff) (Coleoptera: Curculionidae, Scolytinae), los depredadores Enoclerus ablusus Barr (Coleoptera: Cleridae) y Elacatis sp. (Pascoe) (Coleoptera: Salpingidae) fueron atraídos a las combinaciones de ipsenol + a-pineno e ipsdienol + a-pineno; el depredador Temnochila chlorodia Mannerheim (Coleoptera: Trogositidae) respondió a todos los tratamientos. Los depredadores Tenebroides corticalis (Melsheimer) (Coleoptera: Trogositidae) y Temnochila virescens (F.) fueron capturados en números muy bajos. Los resultados de este estudio indican que el depredador T. chlorodia, reconoce y se orienta a los semioquímicos producidos tanto por las especies de descortezador, D. frontalis e I. grandicollis, mientras que los depredadores E. ablusus y Elacatis sp son atraídos exclusivamente por los producidos por las especies de Ips. Las diferentes respuestas de los insectos atrapados son discutidas a la luz de trabajos similares, enfatizando las variaciones encontradas en la asociación descortezador-depredador y la respuesta a los semioquímicos entre las poblaciones de Estados Unidos y las del sur de México para el manejo de los mismos.

The response of Dendroctonus valens and Temnochila chlorodia to Ips paraconfusus pheromone components and verbenone

The red turpentine beetle, Dendroctonus valens LeConte, 1860 (Coleoptera: Curculionidae, Scolytinae), is a common bark beetle found throughout much of North America and China. In 2004, we observed that attack densities of the California fivespined ips, Ips paraconfusus Lanier, 1970 (Coleoptera: Curculionidae, Scolytinae), in logging debris were inversely related to D. valens attacks on freshly cut stumps, which led to the demonstration that components of the aggregation pheromone of I. paraconfusus inhibited the response of D. valens to attractant-baited traps. In this study, we test the response of D. valens and Temnochila chlorodia (Mannerheim, 1843) (Coleoptera: Trogositidae), a common bark beetle predator, to racemic ipsenol, racemic ipsdienol, and (−)-cis-verbenol (IPSR) in the presence and absence of two release rates of (−)-verbenone. The addition of a relatively low release rate of (−)-verbenone (4 mg/24 h) to attractant-baited traps did not affect catch and had no significant effect on the response of D. valens to IPSR. IPSR significantly reduced D. valens attraction to baited traps. The addition of high release rates of (−)-verbenone (50 mg/24 h) to IPSR significantly increased inhibition; however, the effect was not significantly different from that observed with (−)-verbenone alone (50 mg/24 h). Temnochila chlorodia was attracted to traps baited with (−)-β-pinene, (+)-3-carene, and (+)-α-pinene. The addition of (−)-verbenone (50 mg/24 h) significantly increased attraction. Traps baited with IPSR caught significantly more T. chlorodia than those baited with (−)-verbenone. Few other beetles were collected. We are hopeful that these results will help facilitate the development of an effective tool for protecting Pinus spp. from D. valens infestations.

Seasonal Abundance of Temnochila chlorodia (Mannerheim) (Coleoptera: Trogositidae) Collected in Western Pine Beetle Pheromone-Baited Traps in Northern California

Bark beetles (Coleoptera: Scolytidae) are commonly recognized as the most important mortality agent in western coniferous forests. In this study, we describe the abundance of bark beetle predators collected in multiple-funnel traps baited with exo-brevicomin, frontalin and myrcene in northern California during 2003 and 2004. A total of 32,903 Temnochila chlorodia (Mannerheim), 79 Enoclerus lecontei (Wolcott), and 12 E. sphegeus (F.) were collected. The seasonal abundance of E. lecontei and E. sphegeus was not analyzed because too few individuals were collected. In general, T. chlorodia was most abundant in late spring, but a second smaller peak in activity was observed in late summmer. Overall, the ratio of males to females was 0.82. A significant temporal effect was observed in regard to sex ratios with more males collected during later sample periods. Temnochila chlorodia flight activity patterns were similar between years, but activity was generally delayed several weeks in 2003.

Disruption of red turpentine beetle attraction to baited traps by the addition of California fivespined ips pheromone components

The red turpentine beetle, Dendroctonus valens LeConte (Coleoptera: Scolytidae), is a common bark beetle species found throughout much of North America. In California, D. valens and the California fivespined ips, Ips paraconfusus Lanier (Coleoptera: Scolytidae), are sympatric and often colonize the same tree. In an unrelated study, we observed that I. paraconfusus attack densities in logging debris were inversely related to D. valens attacks on freshly cut stumps. In this study, we test the hypothesis that allomonal inhibition occurs between these two species. Components of the aggregation pheromone of I. paraconfusus (racemic ipsenol, (+)-ipsdienol, and (–)-cis-verbenol) inhibited the response of D. valens to attractant-baited traps. Substitution of racemic ipsdienol for (+)-ipsdienol did not alter this effect. Doubling the release rate did not enhance inhibition. Racemic ipsdienol was not attractive to I. paraconfusus. Temnochila chlorodia (Mannerheim, 1843) (Coleoptera: Trogositidae), a common bark beetle predator, was attracted to the I. paraconfusus aggregation pheromone. These results could have important implications for the development of an effective semiochemical-based management tool for D. valens.

Field Response of Dendroctonus valens (Coleoptera: Scolytidae) and a Major Predator, Temnochila chlorodia (Coleoptera: Trogositidae), to Host Kairomones and a Dendroctonus spp. Pheromone Component1

The red turpentine beetle, Dendroctonus valens (LeConte) (Coleoptera: Scolytidae), is a common bark beetle species found throughout much of North America. Aggregation pheromones have yet to be isolated and identified for D. valens. In this study, we examined the response of D. valens and a bark beetle predator, Temnochila chlorodia (Mannerheim) (Coleoptera: Trogositidae), to host produced kairomones and to the Dendroctonus spp. pheromone component exo-brevicomin. A total of 11,604 D. valens and 586 T. chlorodia were captured in multiple-funnel traps over a 14-wk period from 27 March to 5 July 2002. There was no significant difference in trap catch related to gender. The ratio of males to females was 1.01 for D. valens and 0.97 for T. chlorodia. Dendroctonus valens showed significant attraction to (+)-α-pinene, (−)-β-pinene, and (+)-3-carene, but the addition of ethanol did not significantly increase trap catch. Racemic exo-brevicomin was not attractive to D. valens and significantly reduced its attraction to the monoterpene and ethanol blend. This observation, in combination with results from other authors, suggests that D. valens is not responding to the western pine beetle, D. brevicomis LeConte, pheromone or any of the individual components. Potential explanations for why D. valens is attracted to D. brevicomis infested trees are provided. There were no significant differences in the trap catch of T. chlorodia among unbaited traps or traps baited with (+)-α-pinene, (−)-β-pinene, and (+)-3-carene or (+)-α-pinene, (−)-(β-pinene, and (+)-3-carene, and ethanol. The addition of exo-brevicomin significantly increased attraction. During the course of this study, a single peak in flight activity was observed during late May through early June for both species.

VISITATION FREQUENCIES OF SOME INSECT SPECIES ON CERATOCYSTIS WAGENERI INFECTED AND APPARENTLY HEALTHY PONDEROSA PINES

To test the hypothesis that bark beetles and some associated insect species are attracted to ponderosa pines infected by Ceratocystis wageneri, insect visitations on 11 severely diseased, 9 moderately diseased, and 10 apparently healthy trees were monitored from 1 August to 15 October 1972. Larger numbers of Dendroctonus brevicomis, D. ponderosae, Temnochila chlorodia, and buprestids were captured on diseased trees uninfested by bark beetles than on apparently healthy ones, thus possibly indicating attraction to diseased trees. There was strong evidence that D. valens and Spondylis upiformis were attracted more frequently to wounds on diseased than on healthy trees. Arrival patterns of beetles were recorded for trees that became infested during the study. Predators became abundant on traps as bark beetle catches increased.

COMPARATIVE TOXICITY OF LINDANE, CARBARYL, AND CHLORPYRIFOS TO THE WESTERN PINE BEETLE (DENDROCTONUS BREVICOMIS) (COLEOPTERA: SCOLYTIDAE) AND TWO OF ITS PREDATORS, ENOCLERUS LECONTEI (COLEOPTERA: CLERIDAE) AND TEMNOCHILA CHLORODIA (COLEOPTERA: TROGOSITIDAE)

Each of three insecticides—lindane, carbaryl, chlorpyrifos—was tested by topical application on the western pine beetle, Dendroctonus brevicomis LeConte, and two native coleopterous predators, Enoclerus lecontei (Wolc.) and Temnochila chlorodia (Mann.), to assess comparative toxicity. Lindane was more toxic to the predators than to western pine beetle, while carbaryl was relatively non-toxic to E. lecontei when compared with either T. chlorodia or western pine beetle. Chlorpyrifos was equally toxic to all three species. Results of topical application serve to estimate relative effects of insecticides on predacious associates in the western pine beetle community.

EFFECTIVENESS OF THE DOUGLAS-FIR BEETLE ANTIAGGREGATIVE PHEROMONE METHYLCYCLOHEXENONE AT THREE CONCENTRATIONS AND SPACINGS AROUND FELLED HOST TREES

The antiaggregative pheromone 3-methyl-2-cyclohexen-1-one (MCH) of the Douglas-fir beetle (Dendroctonus pseudotsugae Hopk.) was diffused at three rates and three spacings around attractive felled trees. Optimum treatment was ca. 1–2 mg/day at 10-ft spacing (0.06–1.3 g/acre per day), which reduced Douglas-fir beetle attacks and progeny by 96% and 91%, respectively. Progeny in trees exposed to higher than optimum MCH concentration were less mature, but not significantly fewer than progeny in controls. Densities of immature stages of nine other taxa of insects, both entomophagous and commensal, were determined. Abundance of larvae of the predacious clerids Enoclerus sphegeus Fab. and Thanasimus undatulus Say was significantly correlated with abundance of Douglas-fir beetle attacks and progeny. The predator Temnochila chlorodia (Mann.) and the associate Pseudohylesinus nebulosus (Lee.) were more dense on samples in the test area where Douglas-fir beetle population and damage were lowest. Density of the dipterous predator Medetera aldrichii (Wheeler) was correlated with numbers of beetle entrances, but decreased at high MCH concentrations. Abundance of Coeloides brunneri Vier., a braconid parasite, was correlated with numbers of beetle brood. Presence of MCH appeared to increase abundance of the associate Pissodes fasciatus Lec. and modify its distribution in trees. Use of methylcyclohexenone for preventing infestation of susceptible trees is a potential control strategy, but a more practical and effective formulation must be developed.