Tebufenozide resistance selected in Plutella xylostella and its cross‐resistance and fitness cost

Siqueira

Sci. agric. (Piracicaba, Braz.)

et al. 2011

Plutella xylostella is a recurring pest on cruciferous crops around the world. In Brazil, it typically requires large number of insecticide sprays, which may lead to fast evolution of resistance. The aim of this study was to assess the susceptibility of Brazilian diamondback moth populations to the insecticides abamectin, deltamethrin, and spinosad. Leaf dip bioassays were used to determine mortality data obtained after 48 h of exposure to insecticides and subjected to Probit analysis. The population from Bonito, state of Pernambuco, Brazil, had the highest toxicity ratio (20.2 -fold) to abamectin compared to the reference population. The LC 50 values for deltamethrin ranged from 85.2 to 360.1 mg L -1 , demonstrating a high survival of populations in relation to this insecticide field dose rate (7.5 mg L -1). The toxicity ratios of the estimated LC 50 s, however, were very low (varying from 2.2 -to 4.2 -fold). Most populations exhibited toxicity ratios for spinosad, ranging from 2.3 -to 5.1 -fold, while both the LC 50 and LC 95 values reflected a high susceptibility to the spinosad field dosage (120 mg L -1).Only the Bonito -PE population resisted to abamectin, while all P. xylostella populations were resistant to deltamethrin, but particularly susceptible to spinosad because of the absence of selection pressure with it in these areas.

mentioning

confidence: 59%

Resistance of Brazilian diamondback moth populations to insecticides

Siqueira

Sci. agric. (Piracicaba, Braz.)

et al. 2011

“…The particularly high resistance ratio estimated for the Bezerros population to abamectin may be due to previous strong selection pressure exerted with insect growth regulator and pyrethroid insecticides in these areas. Nevertheless, cross-resistance is still possible between these two classes of insecticides as reported by Cao & Han (2006). Selection of P. xylostella for resistance to tebufenozide, an insect growth regulator, led to abamectin resistance associated with enhanced mixed-function oxidases (MFOs) (Qian et al 2008).…”

Section: Discussionmentioning

confidence: 99%

Insecticide resistance in populations of the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), from the state of Pernambuco, Brazil

Vc¹,

Siqueira²,

Je³

et al. 2011

Neotrop. entomol.

The diamondback moth Plutella xylostella (L.) has a great economic importance in Brassicaceae crops in many parts of the world. Recurrent infestations of this pest in growing areas of Pernambuco state, Brazil, have led farmers to frequently spray their crops with insecticides. However, control failures by several insecticides have been alleged by farmers. The objective of this study was to check whether resistance to insecticides could explain these control failures in P. xylostella. Populations of P. xylostella from Pernambuco were collected between January and April 2009. The resistance ratios of P. xylostella populations were compared among ive different active ingredients: abamectin, methomyl, lufenuron, indoxacarb, and diafenthiuron by leaf dipping bioassays using foliar discs of kale leaves. Mortality data were submitted to probit analysis. The P. xylostella populations showed variable response and signi icant resistance to one or more insecticides. The population from Bezerros County exhibited the highest resistance ratios to indoxacarb (25.3 times), abamectin (61.7 times), and lufenuron (705.2 times), when compared to the reference population. The populations from Bonito and Jupi Counties were 33.0 and 12.0 times more resistant to lufenuron and abamectin, respectively, when compared with the reference population. Resistance to methomyl was the least common, but not less important, in at least four populations. These results indicated that control failures were associated with resistance by some of the evaluated insecticides, reinforcing the need for resistance management in areas of the state of Pernambuco.

“…The linkage moiety between the pyrazole oxime and 1,1-dichloropropene were three (7a-7m), four (7n-7p), and five (7q and 7r) carbon chains. As displayed in Table 1, all of the title compounds possessed no activities against Tetranychus cinnabarinus at a concentration of 500 μg/mL, and most of Nowadays, owing to long-term use of traditional pesticides, several field populations of plant pests have already developed high levels of insecticide resistance [22], which leads to the great losses of crop production. Therefore, researchers have to search for novel, efficient, and low toxicity insecticides.…”

Section: Biological Activitiesmentioning

confidence: 99%

“…It has been demonstrated that the dichloro-allyloxy-phenol group is essential for the activity of pyridalyl analogues [20,21]. Nowadays, owing to long-term use of traditional pesticides, several field populations of plant pests have already developed high levels of insecticide resistance [22], which leads to the great losses of crop production. Therefore, researchers have to search for novel, efficient, and low toxicity insecticides.…”

Section: Introductionmentioning

confidence: 99%

Design, Synthesis and Bioactivities of Novel Dichloro-Allyloxy-Phenol-Containing Pyrazole Oxime Derivatives

Dai

Zhuang

et al. 2015

Molecules

Abstract:In this study, in order to find novel biologically active pyrazole oxime compounds, a number of dichloro-allyloxy-phenol-containing pyrazole oximes were designed and synthesized according to the method of active group combination. All of the target compounds were confirmed by 1 H-NMR, 13 C-NMR and elemental analysis. In addition, bioassays showed that all of the newly synthesized compounds had no acaricidal activity against Tetranychus cinnabarinus and low insecticidal activity against Aphis craccivora at tested concentrations. However, most of them displayed excellent insecticidal activity against Oriental armyworm at a concentration of 500 µg/mL, and some designed compounds still exhibited potent insecticidal activity against Oriental armyworm even at the dose of 20 µg/mL, especially compounds 7f, 7n and 7p had 100%, 90% and 90% inhibition rates, respectively, which were comparable to that of the control pyridalyl.