Detection of insecticide resistance in field populations of citrus mealybug Planococcus citri (Risso) (Hemiptera: Pseudococcidae)

435-442Planococcus citri (Risso) (Hemiptera: Pseudococcidae), commonly called citrus mealybug, is a major sporadic pest and found to cause severe yield loss in many fruit crops. Mealybugs are considered “hard to kill pests” using insecticides. In order to study the evolution of insecticide resistance in P. citri, we collected mealybugs from four major fruit crops and bioassay was carried out against four commonly used insecticides belonging to different groups followed by quantification of enzymes. The mortality study revealed evolution of very low to low level of resistance with resistance ratio(RR) ranging from 6.87-14.58-fold (acephate), 7.46-16.39-fold (dichlorvos), 2.00-9.50-fold (imidacloprid) and 9.83-12.75-fold (buprofezin). Elevated levels of detoxifying enzymes were observed in all field collected populations along with the evidence of significant positive correlation between insecticides (OP, imidacloprid and buprofezin) and enzymes (esterase, MFO and GST). The high selection pressure of acephate, dichlorvos and buprofezin in the field collected population could be attributed to the evolution of low level resistance resulting in control failure. Hence, it is suggested to use imidacloprid supplemented with biocontrol strategies for the management of P. citri.</em

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Not AvailablePink mealybug Maconellicoccus hirsutus (Green) (Hemiptera: Pseudococcidae) is a destructive pest of agricultural and horticultural crops. Insecticides are the major tool used to control M. hirsutus. The present study was conducted to evaluate resistance to the commonly used insecticides acephate, dichlorvos, imidacloprid and buprofezin in M. hirsutus collected from seven different geographical locations of mulberry and vineyards in India. Detoxifying enzymes, namely esterase, glutathione S transferase (GST) and cytochrome P-450 (cyt-P450), were quantified in populations. One population from Erode showed a low level of resistance to acephate (resistance ratio [RR] 10.3-fold), one from Salem showed a low level of resistance to dichlorvos (resistance ratio [RR] 13.7-fold), one from Sangli showed a very low level of resistance to imidacloprid (RR 10.2-fold), and one from Chikkaballapur showed a low level of resistance to buprofezin (RR 14.8-fold). Activity ratios for detoxifying enzymes ranged from 1.8- to 4.9-fold for GST, 1.8- to 3.7-fold for esterase and 1.9- to 2.4-fold for cyt-P450. Furthermore, organophosphate resistance and activity of enzymes (esterase, GST and cyt-P450) were positively correlated. To contain the evolution of resistance to M. hirsutus infestation, buprofezin and imidacloprid could be used, supplemented with biointensive integrated management strategies and regular resistance monitoring programs.Not Availabl

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Not AvailableThe shoot and fruit borer, Leucinodes orbonalis has a countrywide distribution and has been categorized as the most destructive and most serious pest causing huge losses in brinjal. In the present study total of 21 populations of L. orbonalis collected mainly from Karnataka and also from Andhra Pradesh, New Delhi and Uttar Pradesh were molecularly characterized. The sequencing resulted in 600-636 bp product of CO I gene and amino acid composition of nucleotide, which varied from 195-206 in different populations. The certain amino acids were either present nor absent in different populations indicating their diversity. The pair-wise genetic distance of L. orbonalis populations ranged from 0.00 to 0.051, suggesting that there was variation in population of L. orbonalis from different locations. The highest genetic distance was observed from the population of Udupi district i.e. 0.051, followed by Koppal district is 0.047, Raichur, Chitoor, Vijayapura, Bagalkot and Guntur population having genetic distance of about 0.039 and other populations have different genetic distances which are related to each other. Therefore, it is inferred that there was no significant molecular diversity within L. orbonalis of different geographical locations of India with respect to COI but there is difference in the amino acid composition and genetic distance among the populationsNot Availabl