Esterase, Glutathione S-Transferase and NADPH-Cytochrome P450 Reductase Activity Evaluation in Cacopsylla pyri L. (Hemiptera: Psyllidae) Individual Adults.

Cacopsylla pyri (L.) (Hemiptera: Psyllidae) is a key pest of pear orchards in Spain. The large number of insecticide treatments necessary for control may be an important contributor to the emergence of resistance. Laboratory toxicity and biochemical assays are necessary to validate the existence of insecticide resistance and establish the underlying mechanisms. All the methodologies developed to evaluate enzyme activity in C. pyri to date have incorporated "pools" of adults to detect minimum activity ranges. In this study, we determined the optimal working conditions for evaluation of the activities of esterase, glutathione S-transferase and NADPH-cytochrome P450 reductase in individual insects via colorimetric methods using a microplate reader. The main factors affecting enzymatic analysis activity, such as enzyme source and substrate concentration, filter wavelength, buffer pH, reaction time and additives, were evaluated for optimization. Determining the frequency of resistant individuals within a population could be used as an indicator for the evolution of insecticide resistance over time. Two laboratory strains, one of them selected with cypermethrin, and two field populations were analyzed for this purpose. The data obtained revealed high values and great variation in the activity ranges of esterase (EST) in the insecticide-selected population as well as in the field populations validating the applied methodology.

Determination of the Baseline Susceptibility of European Populations of Cydia pomonella (Lepidoptera: Tortricidae) to Chlorantraniliprole and the Role of Cytochrome P450 Monooxygenases.

The codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), is the key pest on pome fruit and walnut orchards worldwide. Its resistance to available insecticides has been widely reported. Chlorantraniliprole is an anthranilic diamide that was introduced in European countries in 2008-2009 and acts by activating the insect's ryanodine receptors. The aims of this study were to determine the baseline susceptibility of European populations of C. pomonella to chlorantraniliprole, to establish the discriminant concentrations (DC) to check the possible development of resistance, and to know the role of cytochrome P450 monooxygenases (P450) in the possible susceptibility decrease of field populations to the insecticide. Ten field populations from Spain along with others were used to calculate the baseline response of larvae to chlorantraniliprole incorporated into the diet. A pooled probit line was calculated, and three DC were established: 0.3 mg a.i./kg (close to the LC50), 1.0 mg a.i./kg (close to the LC90), and 10 mg a.i./kg diets (threefold the LC99). The DC were used to test the susceptibility of 27 field populations from France, Germany, Hungary, Italy, and Spain. The corrected mortality observed in all cases ranged within the expected interval, even with Spanish populations that showed between 12.1 and 100.0% of individuals with high P450 activity. However, the mortality caused by the DC0.3 decreased as the mean P450 activity increased. Field populations resistant to other insecticides were susceptible to chlorantraniliprole. The determined baseline codling moth susceptibility is a valuable reference for tracking possible future alterations in the efficacy of the insecticide.

Monitoring resistance of Cydia pomonella (L.) Spanish field populations to new chemical insecticides and the mechanisms involved.

BACKGROUND: Widespread resistance of Cydia pomonella to organophosphates was demonstrated in populations from the Spanish Ebro Valley area which showed high levels of enzymatic detoxification. To determine the efficacy of new insecticides, neonate larval bioassays were carried out on 20 field codling moth populations collected from three different Spanish apple production areas. Synergist bioassays were performed to determine the enzymatic mechanisms involved. RESULTS: The least active ingredients were methoxyfenozide, with 100% of the populations showing significantly lower mortality than the susceptible strain, and lambda-cyhalothrin, with very high resistance ratios (872.0 for the most resistant field population). Approximately 50% of the populations were resistant or tolerant to thiacloprid. By contrast, tebufenozide was very effective in all the field populations, as was chlorpyrifos-ethyl despite its widespread use during the last few years. Indoxacarb, spinosad and chlorantraniliprole also provided high efficacy, as did emamectin and spinetoram, which are not yet registered in Spain. CONCLUSION: The resistant Spanish codling moth populations can be controlled using new reduced-risk insecticides. The use of synergists showed the importance of the concentration applied and the difficulty of interpreting results in field populations that show multiple resistance to different active ingredients. © 2017 Society of Chemical Industry.

Susceptibility to organophosphate insecticides and activity of detoxifying enzymes in Spanish populations of Cydia pomonella (Lepidoptera: Tortricidae).

The mechanisms associated with resistance of codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), to organophosphate insecticides in pome fruit orchards have been shown to depend on the area. Our objectives were to evaluate the susceptibility of Spanish codling moth populations to chlorpyrifos-ethyl, azinphos-methyl, and phosalone, and the activity of three enzymatic systems reported to be involved in resistance. Eleven field populations and a susceptible strain used as a reference were tested using a bioassay consisting in the topical application of a diagnostic concentration on postdiapausing larvae. The enzymatic activity of mixed function oxidases (MFO), glutathione transferases (GST), and esterases (EST) was measured in postdiapausing larvae and adults. A significant decrease in the efficacy of the organophosphates was observed for all field populations, although the decrease was smaller in the case of chlorpyrifos-ethyl. No differences between sexes were detected. In postdiapausing larvae, the activity of the three enzymatic systems was higher in all the field populations than in the susceptible population. The possible implication of EST in codling moth insecticide resistance is reported for the first time in European field populations. In adults, only MFO and GST were implicated. Codling moth resistance to organophosphates in Spanish populations must be taken into account in the implementation of antiresistance strategies.

Huevo, larva en primer estadio y aparato genital femenino de la mariposa Chabuata castanea (Lepidoptera: Noctuidae)

Egg, first larval stage and female genitalia of the moth Chabuata castanea (Lepidoptera: Noctuidae). Egg, first larval stage, and female genitalia of the widely distributed moth Chabuata castanea are described, based on material from Talcahuano, VIII region, Chile. Egg microestructures are illustrated with scannig electron microscope images which show that egg morphology allows identification to species level. Rev. Biol. Trop. 55 (2): 659-664. Epub 2007 June, 29.

Se describe el huevo, larva de primer estadio y aparato genital de la hembra de Chabuata castanea con material proveniente de Talcahuano, VIII región, Chile y de huevos obtenidos en laboratorio. Se fotografiaron los huevos con microscopia electrónica de barrido para analizar las variaciones entre micropila, celdas primarias y secundarias, concluyéndose que las diferencias permiten una identificación al nivel de especie.

[Egg, larva and in the first stage of the female genital tract of the Chabuata castanea moth (Lepidoptera: Noctuidae)]. / Huevo, larva en primer estadio y aparato genital femenino de la mariposa Chabuata castanea (Lepidoptera: Noctuidae).

Egg, first larval stage and female genitalia of the moth Chabuata castanea (Lepidoptera: Noctuidae). Egg, first larval stage, and female genitalia of the widely distributed moth Chabuata castanea are described, based on material from Talcahuano, VIII region, Chile. Egg microestructures are illustrated with scannig electron microscope images which show that egg morphology allows identification to species level.

Nuevas especies altoandinas VII (Lepidoptera: Noctuidae) / New High Andes species VII (Lepidoptera: Noctuidae)

Four new species of Scriptania Hampson (Hadeninae) (3 spp.) and Pseudoleucania Staudinger (1 sp.) (Noctuinae), are described. Female Scriptania lucens Köhler are described and a new geographical record for the species is added; Strigania demerodes (Dyar) n. comb. is reexamined, and the synonymy and morphological variation of male genitalia of Strigania lithophilus (Butler) are given.