Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) is a primary pest of tomato plants and is native to South America. Since the first documented European case in 2006, it has spread throughout the Mediterranean basin and North Africa. Larval stages cause direct feeding damage and reductions to both yield and fruit quality. Chemical insecticides have been the main control tools used against T. absoluta, but decreasing efficacy has been attributed to the development of insecticide resistance. During this study, leaf-dip bioassays were used to quantify responses of five field strains of T. absoluta to insecticides belonging to different chemical classes. The results showed significant variation in susceptibilities to pyrethroids. Pyrethroids are a major class of neurotoxic insecticides and acaricides used extensively over the last four decades. One important mechanism of resistance to pyrethroids, termed knockdown resistance (kdr), has been shown to arise through alterations (point mutations) in the para-type sodium channel protein leading to reduced sensitivity of the insect nervous system to these compounds. Cloning and sequencing of domains II, III, and IV of the T. absoluta sodium channel gene revealed the presence of several kdr mutations previously reported to confer reduced sensitivity in other arthropod species. Diagnostic tools that allow detection in individual larvae and adults were developed and used to screen field samples of diverse geographical origin and assess their distribution in global T. absoluta populations.

Knockdown resistance (kdr and super kdr) mutations in the voltage-gated sodium channel of tomato borer, Tuta absoluta, associated with pyrethroid resistance

RAPISARDA, Carmelo;
2011

Abstract

Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) is a primary pest of tomato plants and is native to South America. Since the first documented European case in 2006, it has spread throughout the Mediterranean basin and North Africa. Larval stages cause direct feeding damage and reductions to both yield and fruit quality. Chemical insecticides have been the main control tools used against T. absoluta, but decreasing efficacy has been attributed to the development of insecticide resistance. During this study, leaf-dip bioassays were used to quantify responses of five field strains of T. absoluta to insecticides belonging to different chemical classes. The results showed significant variation in susceptibilities to pyrethroids. Pyrethroids are a major class of neurotoxic insecticides and acaricides used extensively over the last four decades. One important mechanism of resistance to pyrethroids, termed knockdown resistance (kdr), has been shown to arise through alterations (point mutations) in the para-type sodium channel protein leading to reduced sensitivity of the insect nervous system to these compounds. Cloning and sequencing of domains II, III, and IV of the T. absoluta sodium channel gene revealed the presence of several kdr mutations previously reported to confer reduced sensitivity in other arthropod species. Diagnostic tools that allow detection in individual larvae and adults were developed and used to screen field samples of diverse geographical origin and assess their distribution in global T. absoluta populations.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11769/109123
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