Spruce budworm （Choristoneura fumiferana （Clemens）） is one of the most serious forest insect pests in North America. Laboratory bioassays were performed to determine the lethal doses and lethal time of pyrethrins ...Spruce budworm （Choristoneura fumiferana （Clemens）） is one of the most serious forest insect pests in North America. Laboratory bioassays were performed to determine the lethal doses and lethal time of pyrethrins （a botanical insecticide） on 4th instar larvae of spruce bud-worm using larval dip assay. Results show that the LT50 values（time of 50% larval mortality）for spruce budworm at the pyrethrins concentra-tions of 12.5, 25, 50, 100, and 200 μg·L-1 were 94.78, 45.54, 20.36, 14.39 and 11.37 h, respectively. The percentage of cumulative mortality at the pyrethrins concentrations of 12.5, 25, 50, 100, 200 μg·L-1 was approxi-mately 50%, 67%, 93%, 100% and 100% within 120 h, respectively. The LC50 value （concentration of 50% larval mortality） for the 4th instar lar-vae was 16.1μg·L-1. Thus, larval mortality of spruce budworm increased in a concentration-dependent manner, and lethal time decreased with increasing pyrethin concentrations. These findings suggest that pyrethrins have a potential in controlling spruce budworm populations.展开更多
The effects of nutrition may have subtantial impact on insect evolution by shaping different components of phenotypes. The key to undestanding this evolutionary process is to know how nutritional condition affects add...The effects of nutrition may have subtantial impact on insect evolution by shaping different components of phenotypes. The key to undestanding this evolutionary process is to know how nutritional condition affects additive and nonadditive components of the phenotype. However, this is poorly understood in outbreaking insects. We investigated the additive and nonadditive variation present in food utilization traits in spruce budworm individuals subjected to chronic nutritional stress. A total of 160 full-sib families of spruce budworm （Choristoneurafumiferana Clem.） were raised under laboratory condi- tions, feeding on 2 diets （high and low energy） during 3 generations. Variables tested were pupal mass, consumption rate （RCR）, growth rate （RGR）, approximate digestibility （AD）, the efficiency of conversion of digested food （ECD） and the efficiency of conversion of ingested food （ECI）. Our results show that all traits tested presented a high percentage of nonadditive effects that modulate phenotype expression. We found a significant impact of family × diet interaction on pupal mass, RGR and ECD. Furthermore, these traits exhib- ited the greatest heritability. There was no evidence of presence of maternal effects. The results revealed that food utilization traits may evolve through epigenetics effects, such as phenotypic plasticity. This information can be used by modellers to improve forecast of spruce budworm population dynamics.展开更多
基金This research was supported by Natural Resources Canada, Canadian Forest Service. Project No. CFSCB2005-09.
文摘Spruce budworm （Choristoneura fumiferana （Clemens）） is one of the most serious forest insect pests in North America. Laboratory bioassays were performed to determine the lethal doses and lethal time of pyrethrins （a botanical insecticide） on 4th instar larvae of spruce bud-worm using larval dip assay. Results show that the LT50 values（time of 50% larval mortality）for spruce budworm at the pyrethrins concentra-tions of 12.5, 25, 50, 100, and 200 μg·L-1 were 94.78, 45.54, 20.36, 14.39 and 11.37 h, respectively. The percentage of cumulative mortality at the pyrethrins concentrations of 12.5, 25, 50, 100, 200 μg·L-1 was approxi-mately 50%, 67%, 93%, 100% and 100% within 120 h, respectively. The LC50 value （concentration of 50% larval mortality） for the 4th instar lar-vae was 16.1μg·L-1. Thus, larval mortality of spruce budworm increased in a concentration-dependent manner, and lethal time decreased with increasing pyrethin concentrations. These findings suggest that pyrethrins have a potential in controlling spruce budworm populations.
文摘The effects of nutrition may have subtantial impact on insect evolution by shaping different components of phenotypes. The key to undestanding this evolutionary process is to know how nutritional condition affects additive and nonadditive components of the phenotype. However, this is poorly understood in outbreaking insects. We investigated the additive and nonadditive variation present in food utilization traits in spruce budworm individuals subjected to chronic nutritional stress. A total of 160 full-sib families of spruce budworm （Choristoneurafumiferana Clem.） were raised under laboratory condi- tions, feeding on 2 diets （high and low energy） during 3 generations. Variables tested were pupal mass, consumption rate （RCR）, growth rate （RGR）, approximate digestibility （AD）, the efficiency of conversion of digested food （ECD） and the efficiency of conversion of ingested food （ECI）. Our results show that all traits tested presented a high percentage of nonadditive effects that modulate phenotype expression. We found a significant impact of family × diet interaction on pupal mass, RGR and ECD. Furthermore, these traits exhib- ited the greatest heritability. There was no evidence of presence of maternal effects. The results revealed that food utilization traits may evolve through epigenetics effects, such as phenotypic plasticity. This information can be used by modellers to improve forecast of spruce budworm population dynamics.
