Tools for Resistance Monitoring in Oriental Fruit Moth (Lepidoptera: Tortricidae) and First Assessment in Brazilian Populations

Abstract

In southern Brazilian apple (Malus spp.) orchards, predominantly organophosphates are used to control the oriental fruit moth, Cydia molesta (Busck) (Lepidoptera: Tortricidae), but control failures often occur. Therefore the susceptibility of three C. molesta Brazilian populations was investigated to five insecticides of different groups and modes of action, in comparison with a susceptible laboratory strain mass reared in southern France for >10 yr. At the same time, comparative biochemical and genetic analysis were performed, assessing the activities of the detoxification enzymatic systems and sequencing a gene of insecticide molecular target to find out markers associated with resistance. The three Brazilian populations were significantly resistant to chlorpyrifos ethyl compared with the reference strain. One of the field populations that had been frequently exposed to deltamethrin treatments showed significant decreasing susceptibility to this compound, whereas none of the three populations had loss of susceptibility to tebufenozide and thiacloprid compared with the reference strain. All three populations had slight but significant increases of glutathione transferase and carboxylesterases activities and significant decrease of specific acetylcholinesterase activities compared with the reference. Only the most resistant population to chlorpyriphos exhibited a significantly higher mixed function oxidase activity than the reference. The acetylcholinesterase of females was significantly less inhibited by carbaryl in the Brazilian populations than in the reference strain (1.7-2.5-fold), and this difference was not expressed in the male moth. However, no mutation in the MACE locus was detected. These biological and molecular characterizations of adaptive response to insecticides in C. molesta provide tools for early detection of insecticide resistance in field populations of this pest.

Laboratory Populations: Is It Representative for Bioassays in Relation to Field Populations of Oriental Fruit Moth?

“…Although, P2008, which was used in this study, was the same as that used in studies of resistance conducted in 2008 (Siegwart et al, 2011), manifested resistance to chlorpyrifos in relation to a reference population (multiplied in the laboratory for more than 10 years), and showed a higher activity of AchE and GST. When the P2008 was mantained in the laboratory for 36 generations, under the influence of the artificial medium, many physiological and behavioral characteristics were affected, similar to those occurring in Ceratitis capitata (Diptera: Tephritidae) (Bravo & Neto, 2004) and Grapholita molesta (Jones et al, 2011).…”

“…The presence of this enzyme is often related to resistance to the insecticide Tortricidae (Reyes & Sauphanor, 2008). The high number of applications of organophosphate insecticides in the Brazilian orchards (Siegwart et al, 2011) exerts selection pressure and may feature a contrived example of natural selection (Ffrench-Constant et al, 2004).…”

“…The control in the 1980s and 1990s, was with pyrethroids and organophosphates, and in the late 1990s, insecticides growth regulators were registered, among them, belonging to the group diacylhidrazine. Thus, there was an increase in the prevalence of pesticides in the last 10 years, which may be related to the resistance individuals (Kanga et al, 2003;Jones et al, 2010;Siegwart et al, 2011). For study of resistance should multiplicate insects in laboratory.…”

Resistance of oriental fruit moth (Lepidoptera: tortricidae) to insecticides in apple orchards in southern Brazil

“…Activities of glutathione S-transferase, esterase, and acetylcholinesterase enzymes have been used as biochemical biomarkers of resistant Tortricidae populations in North (KANGA et al, 1997; and South America (SIEGWART et al, 2011).…”

Mating disruption with low density diffusers for the management of oriental fruit moths (Lepidoptera: Tortricidae) in apple orchards under subtropical climate in southern Brazil

“…The total is more than 12 insecticide sprays per season. The frequent use of insecticides in apple orchards may result in the selection of resistant populations, as evidenced by the inefficient control of Lepidoptera that has been frequently observed in Southern Brazil (SIEGWART et al 2011) and other locales (KANGA et al 2001). Some active substances, such as clorpyrifos, phosmet, fenitrothion and methidathion have not shown promising results with regard to the efficiency of pest control which targets using chemical insecticides (L.B.M., unpublished data).…”