The present study is a summary of the current level of the insecticide resistance to selected organophosphates, pyrethroids, and neonicotinoids in seven Indian field populations ofBemisia tabacigenetic groups Asia-I, Asia-II-1, and Asia-II-7. Susceptibility of these populations was varied with Asia-II-7 being the most susceptible, while Asia-I and Asia-II-1 populations were showing significant resistance to these insecticides. The variability of the LC₅₀values was 7x for imidacloprid and thiamethoxam, 5x for monocrotophos and 3x for cypermethrin among the Asia-I, while, they were 7x for cypermethrin, 6x for deltamethrin and 5x for imidacloprid within the Asia-II-1 populations. When compared with the most susceptible, PUSA population (Asia-II-7), a substantial increase in resistant ratios was observed in both the populations of Asia-I and Asia-II-1. Comparative analysis during 2010–13 revealed a decline in susceptibility in Asia-I and Asia-II-1 populations ofB. tabacito the tested organophosphate, pyrethroid, and neonicotinoid insecticides. Evidence of potential control failure was detected using probit analysis estimates for cypermethrin, deltamethrin, monocrotophos and imidacloprid. Our results update resistance status ofB. tabaciin India. The implications of insecticide resistance management ofB. tabacion Indian subcontinent are discussed.

Susceptibility to phosphine was compared in 15 populations of lesser grain borer (Rhyzopertha dominica) collected from grain storage godowns across India. A high level of resistance to phosphine was noticed in R. dominica collected from northern India compared to those collected from northeastern regions of India. The median lethal concentration values varied from 0.024 mg/L to 1.991 mg/L, with 1.63 to 82.96-fold resistance compared to laboratory susceptible checks. Antioxidant enzymes have been reported to negate the reactive oxygen species generated upon encountering the fumigant phosphine. Distinct differences in the activity of antioxidant enzymes were noticed in the field populations exposed to phosphine. Peroxidase activity varied between 1.28 and 336.8 nmol H₂O₂ reduced/min/mg protein. The superoxide dismutase inhibition rate was between 81.29 and 99.66%, and catalase activity varied between 6.28 and 320.13 nmol H₂O₂ reduced/min/mg protein. The findings of our investigation show that the activities of peroxidase and superoxide dismutase are positively linked (p < 0.01) with an increase in resistance ratios, whereas catalase was found to have a negative association with resistance to phosphine. The reported results elucidate the differential activities of principal antioxidant enzymes in scavenging the oxyradicals (O₂^•−, H₂O_2,^•OH) associated with tolerance to phosphine in R. dominica.

Kondwani MsangoSoko, Sakshi Gandotra, Rahul Chandel, Kirti Sharma, Balasubramanian Ramakrishinan, and Sabtharishi Subramanian*. J. Microbiol. Biotechnol. -0001;30:. https://doi.org/10.4014/jmb.2002.02055

Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) an invasive mealybug on cotton is primarily controlled by conventional insecticides. An endoparasitoid Aenasius arizonenesis (Girault) (Hymenoptera: Encyrtidae) is a potential biocontrol agent of this pest. We assessed the susceptibility in field populations of P. solenopsis and A. arizonensis to commonly used insecticides: profenofos, imidacloprid and thiodicarb. Reproductive traits of the parasitoid and Environmental Risk Assessment (ERA) parameters viz., Reduction coefficient, Descriptive analysis, Risk Index (RI), Selectivity ratio and Hazard quotient were measured to assess the direct and indirect effects of these insecticides on the parasitoid. Probit analysis revealed heterogeneity in the insecticide resistance development for both the cotton mealybug and its parasitoid. The field populations of P. solenopsis exhibited resistance to profenofos (18.87–59.86 folds) and thiodicarb (20.07 folds) and susceptibility to imidacloprid. Development of resistance to profenofos was observed in field populations of A. arizonensis. Exposure to lethal doses of imidacloprid and profenofos caused a reduction in parasitization (19–23%) and adult emergence (62–69%) of the parasitoid. Profenofos, thiodicarb and imidacloprid were found to be hazardous, non-selective and harmful to the endoparasitoid, A. arizonensis. There is an urgent need for optimizing insecticide applications for sustainable management of this invasive mealybug in cotton.