Seasonal Dynamics of Metabolic Mechanisms Mediating Pyrethroid Resistance inHelicoverpa armigerain Central India

Abstract

Very high cypermethrin and fenvalerate resistance frequencies were recorded in Helicoverpa armigera (Hübner) populations in central India during the 1993–94, 1994–95 and 1995–96 cropping seasons. Synergism assays and biochemical analyses of detoxification enzyme levels indicated that mono‐oxygenases and esterases were important metabolic mechanisms mediating pyrethroid resistance. Piperonyl butoxide‐ (PBO) and profenofos‐suppressible pyrethroid resistance were correlated with enhanced levels of cytochrome P450 and general esterases respectively. Enzyme assay data indicated that high cytochrome P450 levels generally coincided with low esterase activity and vice versa. Similarly, synergist bioassays showed that PBO‐insensitive resistance was frequently associated with profenofos‐sensitive resistance and vice versa. Oxidase‐ and esterase‐mediated mechanisms evidently alternated in a reciprocal manner, with perceptible shifts in relative importance occurring during mid‐October in all three seasons and in late January in 1995. Apart from metabolic mechanisms, a synergist‐insensitive resistance mechanism (believed to be nerve insensitivity), accounted for an average of 51, 30 and 28% of cypermethrin resistance during the 1993–94, 1994–95 and 1995–96 seasons respectively. © 1997 SCI.

Esterase‐mediated resistance to pyrethroids in field populations of Helicoverpa armigera (Lepidoptera: Noctuidae) from Central Africa

“…The most frequently documented metabolic mechanisms in H. armigera resistance to pyrethroids are related to (i) esterase overproduction, as shown in China, 13 India 11,16 and Australia, the role of the esterase being to bind and sequester pyrethroid insecticides, consistent with the large resistance factors observed, 9,10,43 and (ii) elevated levels of cytochrome P450 monooxygenases, as previously described in China, India, Pakistan and West Africa. 24,40 To the authors' knowledge, this is the first report of esterasemediated resistance of H. armigera to pyrethroid insecticides in the West to Central Africa cotton belt.…”

“…The absence of cross-resistance to DDT ruled out a possible target-site modification mechanism (nerve insensitivity) found to mediate pyrethroid resistance of H. armigera in Australia, Asia and India. 8,11,15,16,18,19 The absence of cross-resistance to DDT, as previously reported in West Africa, 39 also suggests that pyrethroid resistance did not originate from previous treatments with organochlorine insecticides. The laboratory-selected strain GS-RR06, as well as the five tested field populations (from tomato, cotton and maize), were highly resistant to both cypermethrin and deltamethrin, with significant correlation between LD 50 values, but only weakly (two field populations from Pitoa) or not resistant to etofenprox, with no correlation between LD 50 values.…”

“…This result suggests that PBO did not efficiently inhibit these particular esterase isozymes (but rather oxidases) or that additional mechanisms may be involved in resistance. 11,16,41 Alternatively, a longer lapse of time between application of the inhibitor and the insecticide would have increased the magnitude of the response. 10 Young et al 35 reported that esterase inhibition by PBO does not occur immediately, but exhibits maximum inhibition 3-4 h after dosage, and that topical bioassays using PBO show maximum H. armigera mortality with pre-treatment times corresponding to maximum esterase inhibition.…”

“…4,8,19,20 Profenofos (3.2 µg larva −1 ) was also applied in combination with cypermethin on the GS-RR08 strain, as an indicator of esterase-mediated pyrethroid resistance. 10,16 Such a concentration did not result in any mortality in this strain. Treated larvae were kept at a constant temperature of 25 ± 2 • C under a 14 : 10 h light : dark photoperiod.…”

Status of insecticide resistance in field populations of tomato fruit borer (Helicoverpa armigera) (Lepidoptera: Noctuidae) in Punjab, India

“…Indiscriminate and extensive use of chemical insecticides in past few decades has led to development of resistance and hence the management of Helicoverpa has become increasingly difficult due to development of resistance to most commonly used chemical class of insecticides were reported earlier by various workers (Armes et al 1996, Kranthi 1997, Ramasubramaniam and Regupathy 2004. Various insecticides belonging to different classes are being used for the management of this pest all over the world.…”