Sitobion avenae(F.) and Rhopalosiphum padi(L.) are two important pests of wheat in China.They typically coexist in fields during the late period of wheat growth.Sulfoxaflor is a novel sulfoximine insecticide that demo...Sitobion avenae(F.) and Rhopalosiphum padi(L.) are two important pests of wheat in China.They typically coexist in fields during the late period of wheat growth.Sulfoxaflor is a novel sulfoximine insecticide that demonstrates broad-spectrum efficacy,especially in targeting sap-feeding insects.This study was carried out to investigate the sublethal effects of sulfoxaflor on the development,longevity,and reproduction of two species of wheat aphids.Our results showed that sublethal concentrations of sulfoxaflor did not cause significant effects on the fecundity or the longevity of the parent generation(F0 generation) of either S.avenae or R.padi.However,it caused transgenerational sublethal effects.For S.avenae,adult longevity of F1 generation was significantly decreased.No significant differences were observed on the population parameters of S.avenae in the F1 generation.For R.padi,the adult preoviposition period(APOP) and the total preoviposition period(TPOP) of F1 generation were significantly reduced.The mean generation time(T) was significantly reduced in the R.padi F1 generation.What’s more,the intrinsic rate of increase(rm) and the finite rate of increase(λ) were significantly increased in the R.padi F1 generation.Taken together,these results suggest that exposure to the LC25 of sulfoxafl had no effects on the parent generation of S.avenae or R.padi,but it reduced adult longevity of S.avenae as a negative effect and increased the rm and λ of R.padi in the first progeny generation,which may have an impact on the population dynamics of R.padi.展开更多
Gut content analysis is a useful tool when studying arthropod predator-prey interactions. We used polymerase chain reaction （PCR） technique to examine how detection of prey DNA in the gut content of predators was in...Gut content analysis is a useful tool when studying arthropod predator-prey interactions. We used polymerase chain reaction （PCR） technique to examine how detection of prey DNA in the gut content of predators was influenced by digestion time and temperature. Such knowledge is critical before applying PCR-based gut content analysis to field collected predators. Larvae of the two-spotted ladybeetle （Adalia bipunctata L.） were fed with the bird cherry-oat aphid （Rhopalosiphum padi L.） at either 21℃ or 14℃. After consuming one aphid, the predators were allowed to digest the prey for a range of time periods up to 24 hours. The influence of temperature on A. bipunctata feeding behavior was also recorded. From the fed larvae, total DNA was extracted and PCR reactions with R. padi specific primers were run. The number ofA. bipunctata that tested positive for R. padi DNA was negatively related to the length of digestion time. Temperature influenced larval feeding behavior but did not have a significant effect on R. padi DNA detection. After pooling the data from both temperature treatments we estimated the time point when R. padi DNA could be amplified from 50% of the fed A. bipunctata by PCR to be 4.87 hours. With such a rapid decrease in prey DNA detection success, positive PCR reactions will most likely be the result of predation events occurring shortly before capture. If a defined digestion temperature range has proven not to influence prey detection, PCR data obtained from predators collected within that particular range can be interpreted in the same way.展开更多
基金supported by the National Barley Industry Technology System of China(CARS-05)
文摘Sitobion avenae(F.) and Rhopalosiphum padi(L.) are two important pests of wheat in China.They typically coexist in fields during the late period of wheat growth.Sulfoxaflor is a novel sulfoximine insecticide that demonstrates broad-spectrum efficacy,especially in targeting sap-feeding insects.This study was carried out to investigate the sublethal effects of sulfoxaflor on the development,longevity,and reproduction of two species of wheat aphids.Our results showed that sublethal concentrations of sulfoxaflor did not cause significant effects on the fecundity or the longevity of the parent generation(F0 generation) of either S.avenae or R.padi.However,it caused transgenerational sublethal effects.For S.avenae,adult longevity of F1 generation was significantly decreased.No significant differences were observed on the population parameters of S.avenae in the F1 generation.For R.padi,the adult preoviposition period(APOP) and the total preoviposition period(TPOP) of F1 generation were significantly reduced.The mean generation time(T) was significantly reduced in the R.padi F1 generation.What’s more,the intrinsic rate of increase(rm) and the finite rate of increase(λ) were significantly increased in the R.padi F1 generation.Taken together,these results suggest that exposure to the LC25 of sulfoxafl had no effects on the parent generation of S.avenae or R.padi,but it reduced adult longevity of S.avenae as a negative effect and increased the rm and λ of R.padi in the first progeny generation,which may have an impact on the population dynamics of R.padi.
文摘Gut content analysis is a useful tool when studying arthropod predator-prey interactions. We used polymerase chain reaction （PCR） technique to examine how detection of prey DNA in the gut content of predators was influenced by digestion time and temperature. Such knowledge is critical before applying PCR-based gut content analysis to field collected predators. Larvae of the two-spotted ladybeetle （Adalia bipunctata L.） were fed with the bird cherry-oat aphid （Rhopalosiphum padi L.） at either 21℃ or 14℃. After consuming one aphid, the predators were allowed to digest the prey for a range of time periods up to 24 hours. The influence of temperature on A. bipunctata feeding behavior was also recorded. From the fed larvae, total DNA was extracted and PCR reactions with R. padi specific primers were run. The number ofA. bipunctata that tested positive for R. padi DNA was negatively related to the length of digestion time. Temperature influenced larval feeding behavior but did not have a significant effect on R. padi DNA detection. After pooling the data from both temperature treatments we estimated the time point when R. padi DNA could be amplified from 50% of the fed A. bipunctata by PCR to be 4.87 hours. With such a rapid decrease in prey DNA detection success, positive PCR reactions will most likely be the result of predation events occurring shortly before capture. If a defined digestion temperature range has proven not to influence prey detection, PCR data obtained from predators collected within that particular range can be interpreted in the same way.
