RESUMO
Spruce budworm, Choristoneura fumiferana Clemens, is an ecologically significant defoliator of spruce and balsam fir in North America. Optimization of semiochemical-mediated control is needed to improve the existing integrated pest management systems such as mating disruption and population estimation. This study used single sensillum recordings (SSR) to identify the responses of olfactory receptor neurons (ORNs) in the antennal sensilla of adult male and female C. fumiferana to host plant volatiles, and female sex pheromones. There have been few SSR studies done on spruce budworm, and to our knowledge, the present study represents the first attempt to examine the responses of ORNs from antennal sensilla in response to a range of host and conspecific stimuli. A total of 86 sensilla were characterized and sorted into 15 possible sensillum categories based on odor responses. We observed that specialist sensilla responding to few ligands were more abundant in both male and female than sensilla exhibiting more generalized odorant responses. (E/Z)-11-tetradecenal elicited responses from ORNs from any sensilla which were sensitive to pheromones in both males and females. Female C. fumiferana ORNs were able to detect and physiologically respond to female-produced sex pheromones with the same degree of sensitivity as their male counterparts. Together, these data improve our knowledge of mechanisms by which adult budworms respond to pheromone and host plant volatiles and provide insights that may be complementary to existing integrated pest management (IPM) strategies based on the chemical ecology of spruce budworm.
RESUMO
Choristoneura fumiferana (SBW) is a major defoliating pest of balsam fir and spruce in eastern North America. As part of an integrated management strategy for SBW, we evaluated the effectiveness of mating disruption as a landscape-level population control tactic. Using a sprayable formulation (CONFOUNDSBW) containing a synthetic sex pheromone blend, we treated five 300 ha blocks in Northern New Brunswick with an aerially applied microencapsulated mixture. There were significant reductions in adult trap catches in treated blocks compared to untreated control blocks. Branch sampling in treated blocks showed uniform distribution of CONFOUNDSBW deposition throughout the blocks. Population densities following treatment were not significantly affected when compared to densities in control blocks, or prior to treatment. Analysis of egg:adult ratios indicates that no immigration events occurred within treatment or control blocks. The lack of population reduction following treatment strongly suggests that widespread application of CONFOUNDSBW at a rate of 50 g of active ingredient per hectare is not an effective tool in controlling SBW populations.
RESUMO
Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae) is a defoliating pest in Canada and the northeastern United States. Given its important ecological and economic effects in affected regions, several direct management techniques have been developed, including the application of the insect growth regulator tebufenozide (Mimic™, RH-5992) to feeding larval stages. While the effectiveness of tebufenozide, in this capacity, is understood, management programs of other lepidopteran pests have demonstrated the effectiveness of tebufenozide application when utilized against other life stages. Here, we investigated the toxicity of topically-applied tebufenozide to C. fumiferana pupae to determine if such a strategy could be feasible. We observed significant dose-dependent decreases in the likelihood of adult emergence, increases in the likelihood of pupal death or adult deformity at eclosion, and significant decreases in mean adult longevity. Estimated LD 50 (lethal dose) values for adult male and female C. fumiferana treated as pupae ≤ 4 days after pupation were approximately 1-3 and 2-3.5% ACI (active commercial ingredient) respectively. Estimated L-SD (lethal-sublethal) 50 doses for adult male and female C. fumiferana treated as pupae ≤4 days after pupation were <1, and <2% ACI, respectively. Mating success was also significantly lower in mating pairs containing adults treated as pupae. Although, the amounts required to cause appreciable pupal mortality were much higher than those currently applied operationally in the C. fumiferana system, our study illustrates the potential of tebufenozide to utilized against additional developmental stages in other lepidopteran pests.
RESUMO
Male Lepidoptera often possess specialized scales, called hair pencils that emit volatiles that are critical to mating success. Spruce budworm, Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae), males will display hair pencils to females before attempting copulation. The importance of volatiles on these hair pencils is, however, not clear. We compared the proportion of successful copulations in unmanipulated mating pairs to pairs where males had their hair pencils either removed or chemically washed, and to pairs where females were antennectomized. Mean proportions of successful matings were significantly lower in pairs where hair pencils had been manipulated or where females had been antennectomized compared with unmanipulated mating pairs. There was no significant difference in mating success between treatments where hair pencils had been manipulated; however, mating success was significantly lower in hair pencil treatments than in antennectomized treatments. Mean copulation proportions in hair pencil/antennectomized treatments were also significantly less than in respective sham-operated treatments. Our results suggest that volatiles are associated with hair pencils, and they may be required for mating success in C. fumiferana.
