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Tobacco-adapted Form (tobacco-adapted + form)
Selected AbstractsMonitoring for imidacloprid resistance in the tobacco-adapted form of the green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae), in the eastern United StatesPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 6 2010Lakshmipathi Srigiriraju Abstract BACKGROUND: Imidacloprid is the primary insecticide for controlling the tobacco-adapted form of the green peach aphid (TGPA), Myzus persicae (Sulzer), a major pest of tobacco worldwide. This study used leaf-dip bioassays to assess TGPA resistance to imidacloprid in the eastern United States from 2004 through 2007. RESULTS: When combined over the 4 year study, 18, 14 and 3% of the TGPA had imidacloprid resistance ratios (RRs) of 10,20-fold, 20,30-fold and 30,90-fold, respectively, compared with the most susceptible colony tested. This indicates that some colonies have developed moderate levels of resistance to imidacloprid. A colony collected near Clayton, North Carolina, had the highest RR of 91 (LC50 value = 31 mg L,1). This resistance declined for six tests over a 3 year period in the laboratory culture from >130-fold RR (LC50 = 48 mg L,1) to 40-fold RR (LC50 = 15 mg L,1). Over the same period, the most susceptible colony and a standard colony not exposed to imidacloprid for over 7 years had consistently low LC50 values. CONCLUSION: Moderate levels of resistance to imidacloprid are noticed among TGPA colonies from the eastern United States. The variation in resistance indicates that the factors responsible are present in the populations at low frequencies and are just not enough to cause field failures yet. Copyright © 2010 Society of Chemical Industry [source] Esterase-based resistance in the tobacco-adapted form of the green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae) in the eastern United StatesARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 2 2009Lakshmipathi Srigiriraju Abstract Organophosphates and carbamates represent alternative insecticides in managing the tobacco-adapted form of the green peach aphid (TGPA), Myzus persicae (Sulzer), a major pest of tobacco in the United States and around the world. General esterases that detoxify these insecticides were assessed in green, red, and orange morphs of field-collected M. persicae. A total of 136 aphid colonies were collected from 2004 though 2007 and screened for total esterase activity. The green morphs had lower esterase levels, with a mean of 77±6.6,nmol/min/mg protein, as compared to red (84±2.9,nmol/min/mg protein) and orange morphs (172±16.5,nmol/min/mg protein). Overall esterase activities, and those for the red and green morphs, were positively correlated with LC50 values for acephate (organophosphate) and methomyl (carbamate) assessed in leaf-dip bioassays. Esterase genes responsible for higher esterase activities were diagnosed by gene amplification studies. Twenty-three of 24 colonies tested had either the E4 or FE4 gene amplified, both known to confer esterase-based resistance. Fifteen out of the 24 colonies tested had amplified E4 gene and four colonies had FE4 gene amplification. All orange morphs and one green morph had both E4 and FE4 genes amplified. This unique phenotype, where two esterase genes were amplified had an 865-bp band characteristic of the FE4 gene and an additional 381-bp band characteristic of a deleted upstream region of the E4 gene. Changes that occurred in esterase-based resistance in the TGPA over the past two decades and their implications on insecticide resistance management are discussed. © 2009 Wiley Periodicals, Inc. [source] | ||||||||||