Revealing insights into Bemisia tabaci dynamics: natural enemy communities and population traits in Bt and non-Bt cotton

Whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), poses a significant threat to agricultural and horticultural crops, causing economic damage by direct feeding on plant foliage and through indirect transmission of plant viruses. The current study investigated the occurrence and population dynamics of B. tabaci and its natural enemies in both Bacillus thuringiensis (Bt) and non-Bt cotton fields over a period of 3-years. The study found endurance of B. tabaci populations in both Bt and non-Bt cotton for a period of 23 weeks. Comparatively, in Bt cotton the higher densities of B. tabaci adult population (13.47 ± 8.03 adults/leaf) were recorded during the last week of July (30th SMW) and nymphal population (91.16 ± 82.67 nymphs/leaf) mid-August (33rd SMW. Similarly, in non-Bt cotton, the peak densities were observed during the last week of July (30th SMW) for adults and during the last week of August (34th SWM) for nymphs with the correspondent value of 7.73 ± 3.64 adults/leaf and 35.66 ± 33.37 nymphs/leaf, respectively. Referring to natural enemies’ diversity, a total of 25 natural enemies were identified, comprising of 23 predators and each one species each of parasitoid and entomopathogenic fungi in both Bt and non-Bt cotton. Primarily, the aphelinid parasitoid Encarsia lutea (Masi) (71.29%) and coccinellid predator, Serangium parcesetosum Sicard (7.76%) were prevalent across the 3 years study period. It was perceived from the study that no significant differences in natural enemies’ abundance was observed between Bt and non-Bt cotton. Furthermore, in both Bt and non-Bt cotton the population dynamics of B. tabaci and its natural enemies was greatly influenced by the climatic variables like maximum and minimum relative humidity, temperature, and precipitation. The study revealed a higher population of B. tabaci in Bt cotton compared with non-Bt cotton, and observed regulating of this insect population by natural enemies and climatic conditions. These findings underscore the importance giving consideration to natural enemies of B. tabaci and their population dynamics in the development of Integrated Pest Management (IPM) strategies for sustainable cotton production. Conservation efforts targeting the diverse natural enemies community could further contribute to effective pest management.