Imidacloprid is a neonicotinoid insecticide used for managing the Asian citrus psyllid,Diaphorina citri Kuwayama,which serves as vector of phytopathogens causing citrus greening.However,development of resistance to ne...Imidacloprid is a neonicotinoid insecticide used for managing the Asian citrus psyllid,Diaphorina citri Kuwayama,which serves as vector of phytopathogens causing citrus greening.However,development of resistance to neonicotinoids among populations of D.citri has coincided with occasional control failures in the field.The objectives of this research were to(1)survey current levels of imidacloprid resistance in Florida citrus;(2)compare feeding behavior between imidacloprid-resistant and susceptible D.citri using electrical penetration graph recordings,and(3)investigate the possible amplification of insecticide hormoligosis associated with resistance.Field surveys confirmed that the susceptibility of D.citri populations to imidacloprid has decreased in commercial Florida citrus groves compared with a laboratory-susceptible population.Following 12 generations of selection,resistance to imidacloprid increased by 438 fold compared with the susceptible strain.Imidacloprid-susceptible D.citri feeding on citrus exhibited significantly more bouts associated with intercellular pathway(C),phloem penetration(D),phloem salivation(E1),and nonprobing(Np)activities than imidacloprid-resistant counterparts.However,there were no differences observed in the frequency or duration of phloem ingestion or xylem feeding between susceptible and resistant D.citri.There was no statistical difference in fecundity between resistant and susceptible strains.However,the fecundity of imidacloprid-susceptible female D.citri treated with a sublethal concentration of imidacloprid(LC_(25))increased significantly compared with controls,while such hormoligosis was less pronounced among imidacloprid-resistant psyllids.Our results suggest that imidacloprid-resistant psyllids may cease feeding sooner than susceptible counterparts following sublethal exposure to this insecticide,indicative of a behavioral resistance mechanism.展开更多
This article was to study the potential resistance mechanism of three different wheat varieties （Ww2730, Xiaoyan 22 and Batis） in the seedling stage to Sitobion avenae. The aphid feeding behavior was ascertained by ...This article was to study the potential resistance mechanism of three different wheat varieties （Ww2730, Xiaoyan 22 and Batis） in the seedling stage to Sitobion avenae. The aphid feeding behavior was ascertained by stylet penetration activities monitoring using the electrical penetration graph （EPG） technique. When the aphids feed on Ww2730 seedlings, the time for the 1st duration probing was later than that on Xiaoyan 22 and Batis significantly, and the number of interrupted probing before the 1st duration probing was more than that on Xiaoyan 22 and Batis significantly, and the 1st duration probing was shorter than that on Xiaoyan 22 and Batis significantly. The durations of the stylet pierce from the extra- to the intra-cellular （pd Ⅱ-1） on Ww2730 and Xiaoyan 22 were longer than those on Batis significantly. The duration of the potential drop （pd） in C wave on Ww2730 was longer than that on Xiaoyan 22 and Batis significantly. The times and duration of the G wave （ingestion in xylem） on Ww2730 were more and longer than those on Xiaoyan 22 and Batis significantly. The times of spot G wave on Batis was more than that on Ww2730 significantly, but the duration of spot G was shorter than that on Xiaoyan 22 and Ww2730 significantly. The total time of E1 wave, the longest duration of E1 fractions, and the mean duration time of E1 fractions that followed E2 wave on Xiaoyan 22 and Batis were all significantly longer than those on Ww2730. There was no difference of the mean duration of the 1st E1 wave on the 3 varieties, but the mean durations of other E1 wave on Ww2730 and Xiaoyan 22 were shorter than those on Batis significantly. The other wave parameters, including times and durations of F and E2 were all not different on the 3 wheat varieties. It is suggested that the resistance mechanism of wheat variety Ww2730 to S. avenae is a restriction factor of feeding in epidermis, the thicker cell wall in mesophyll, and secondary metabolites or nutrition unbalance in phloem in the seedling phase. The re展开更多
基金supported by a grant from the Citrus Research and Development Foundation and USDA APHIS MAC funding to LLS。
文摘Imidacloprid is a neonicotinoid insecticide used for managing the Asian citrus psyllid,Diaphorina citri Kuwayama,which serves as vector of phytopathogens causing citrus greening.However,development of resistance to neonicotinoids among populations of D.citri has coincided with occasional control failures in the field.The objectives of this research were to(1)survey current levels of imidacloprid resistance in Florida citrus;(2)compare feeding behavior between imidacloprid-resistant and susceptible D.citri using electrical penetration graph recordings,and(3)investigate the possible amplification of insecticide hormoligosis associated with resistance.Field surveys confirmed that the susceptibility of D.citri populations to imidacloprid has decreased in commercial Florida citrus groves compared with a laboratory-susceptible population.Following 12 generations of selection,resistance to imidacloprid increased by 438 fold compared with the susceptible strain.Imidacloprid-susceptible D.citri feeding on citrus exhibited significantly more bouts associated with intercellular pathway(C),phloem penetration(D),phloem salivation(E1),and nonprobing(Np)activities than imidacloprid-resistant counterparts.However,there were no differences observed in the frequency or duration of phloem ingestion or xylem feeding between susceptible and resistant D.citri.There was no statistical difference in fecundity between resistant and susceptible strains.However,the fecundity of imidacloprid-susceptible female D.citri treated with a sublethal concentration of imidacloprid(LC_(25))increased significantly compared with controls,while such hormoligosis was less pronounced among imidacloprid-resistant psyllids.Our results suggest that imidacloprid-resistant psyllids may cease feeding sooner than susceptible counterparts following sublethal exposure to this insecticide,indicative of a behavioral resistance mechanism.
基金This study was supported financially by the Cooperation Project Foundation between the Ministries of Agriculture of Germany and China(02/03)National Natural Science Foundation of China(39970112)Youth Foundation of Northwest A&F University(080807,08080252).
文摘This article was to study the potential resistance mechanism of three different wheat varieties （Ww2730, Xiaoyan 22 and Batis） in the seedling stage to Sitobion avenae. The aphid feeding behavior was ascertained by stylet penetration activities monitoring using the electrical penetration graph （EPG） technique. When the aphids feed on Ww2730 seedlings, the time for the 1st duration probing was later than that on Xiaoyan 22 and Batis significantly, and the number of interrupted probing before the 1st duration probing was more than that on Xiaoyan 22 and Batis significantly, and the 1st duration probing was shorter than that on Xiaoyan 22 and Batis significantly. The durations of the stylet pierce from the extra- to the intra-cellular （pd Ⅱ-1） on Ww2730 and Xiaoyan 22 were longer than those on Batis significantly. The duration of the potential drop （pd） in C wave on Ww2730 was longer than that on Xiaoyan 22 and Batis significantly. The times and duration of the G wave （ingestion in xylem） on Ww2730 were more and longer than those on Xiaoyan 22 and Batis significantly. The times of spot G wave on Batis was more than that on Ww2730 significantly, but the duration of spot G was shorter than that on Xiaoyan 22 and Ww2730 significantly. The total time of E1 wave, the longest duration of E1 fractions, and the mean duration time of E1 fractions that followed E2 wave on Xiaoyan 22 and Batis were all significantly longer than those on Ww2730. There was no difference of the mean duration of the 1st E1 wave on the 3 varieties, but the mean durations of other E1 wave on Ww2730 and Xiaoyan 22 were shorter than those on Batis significantly. The other wave parameters, including times and durations of F and E2 were all not different on the 3 wheat varieties. It is suggested that the resistance mechanism of wheat variety Ww2730 to S. avenae is a restriction factor of feeding in epidermis, the thicker cell wall in mesophyll, and secondary metabolites or nutrition unbalance in phloem in the seedling phase. The re
