Status of insecticide resistance and detoxification enzymes activity in pink bollworm, Pectinophora gossypiella (Saunders) populations from India

Assessment of Insecticide Resistance, Biological Characteristics, and Detoxification Enzyme Activity in Rice Brown Planthopper (Nilaparvata lugens) from the Gangavathi Region, India

The brown planthopper, Nilaparvata lugens (Stål), is a major insect pest of rice, and its management is increasingly constrained by insecticide resistance. This study assessed insecticide susceptibility, detoxification enzyme activity, and biological characteristics in a Gangavathi field population relative to a long-term susceptible glasshouse population. Resistance ratios were highest for buprofezin (1403.3-fold), imidacloprid (931.3-fold), and ethiprole + imidacloprid (515.7-fold), while thiamethoxam reached 124.0-fold. Chlorpyriphos resistance ratios ranged from 3.6- to 3.9-fold, whereas acephate, dinotefuran, fipronil, and pymetrozine showed ratios below three-fold. Esterase, glutathione S-transferase, and cytochrome P450 monooxygenase activities in the Gangavathi population were 2.2-, 1.8-, and 4.9-fold higher, respectively, than those in the susceptible population. The field population also showed a longer pre-oviposition period (4.3 days), incubation period (7.9 days), nymphal duration (13.7 days), and total life cycle (25.9 days). Conversely, egg hatchability (72.6%), fecundity (221.4 eggs per female), nymphal survival (77.5%), female proportion (53.7%), and brachypterous forms (50.1%) were lower than those recorded in the susceptible population. The findings demonstrate substantial resistance to several frequently used insecticides, particularly buprofezin and imidacloprid, accompanied by enhanced detoxification enzyme activity and altered biological performance. These results provide a basis for location-specific resistance surveillance and the judicious selection of insecticides within integrated brown planthopper management programmes.

Long-term monitoring of insecticide resistance in pink bollworm in Israeli pima cotton fields

Insecticide Susceptibility and Toxicity against Pink Bollworm (Pectinophora gossypiella Saunders) Populations in Cotton

A laboratory study was conducted to evaluate the susceptibility of field populations of the pink bollworm, Pectinophora gossypiella (Saunders), collected from five major cotton-growing tehsils of Bharuch district, Gujarat, during the kharif seasons of 2024-25 and 2025-26. Populations from Amod, Bharuch, Jambusar, Netrang and Valia were tested against seven commonly used insecticides using a diet incorporation bioassay, with a susceptible Surat population as the reference. Larval mortality was assessed across seven concentrations, and LD₅₀-based toxicity indices were used to compare population susceptibility and relative insecticidal toxicity. Mortality increased with increasing insecticide dose across the tested populations. Across insecticides, the highest cumulative mortality in the field populations ranged from 81.25 to 98.65% in Netrang, 82.34 to 93.06% in Bharuch, 67.56 to 90.28% in Amod, 65.45 to 80.38% in Jambusar and 63.70 to 79.73% in Valia. Toxicity-index analysis indicated comparatively greater susceptibility in the Netrang population for most insecticides, whereas Valia and Jambusar generally showed lower susceptibility. Among the tested insecticides, emamectin benzoate, indoxacarb, lambda-cyhalothrin and spinosad showed comparatively higher toxicity, while profenofos and chlorpyrifos were relatively less effective. The observed spatial variation in susceptibility supports the value of location-specific monitoring for insecticide selection and resistance-management planning in cotton. The results provide a laboratory-based comparison of local population susceptibility profiles.

Early indicators of Bt resistance: Variation in Cry toxin susceptibility in field populations of Helicoverpa armigera (Hübner) from India

Stage-specific Toxicity and Efficacy of Different Insecticides in the Management of White Grub (Brahmina coriacea)

Brahmina coriacea (Hope) is a prominent white grub species and a serious soil-dwelling pest, causing considerable damage to various agricultural and horticultural crops in the northwestern Himalayan region of India. The present study assessed the toxicity of selected insecticides against third-instar grubs, adults, and eggs of B. coriacea under laboratory conditions. Among the tested insecticides, chlorantraniliprole was the most effective across all life stages, recording the lowest LD50 values in grubs (1.41 μg per grub) and adults (0.23 μg per beetle), and the highest egg mortality (53.14%). Bifenthrin showed comparable toxicity to chlorantraniliprole in grubs, while carbofuran and chlorpyriphos exhibited moderate effectiveness; fipronil was consistently the least toxic. Adults were more susceptible than grubs, as indicated by lower LD50 values. Egg mortality increased significantly with exposure period, i.e. 18.43% at 3 days to 49.44% at 14 days after treatment, demonstrating a clear time-dependent effect. Overall, chlorantraniliprole emerged as the most potent insecticide against B. coriacea. The findings highlight the importance of considering life-stage differences in insecticide efficacy and provide a scientific basis for optimising pest management strategies targeting B. coriacea.

Biocontrol potential of native entomopathogenic fungi against Phyllotreta spp. (Coleoptera: Chrysomelidae) on radish: a study of damage suppression and population dynamics