The toxicity of seven biorational insecticides [five insect growth regulators (Buprofezin, Fenoxycarb, Pyriproxyfen, Methoxyfenozide, and Tebufenozide) and two oil-extracts of neem and bitter gourd seeds] againstBemisia tabaciand their selectivity for its parasitoid,Encarsia formosawere evaluated in laboratory and field conditions for 2 years (2018–2019) in Pakistan. Toxicity results demonstrate that Pyriproxyfen, Buprofezin, and Fenoxycarb proved to be effective (80–91% mortality and 66.3–84.2% population-reduction) againstB. tabacifollowed by Methoxyfenozide, Tebufenozide (50–75% mortality and 47.8–52.4% population-reduction), and then oil-extracts of neem and bitter gourd (25–50% mortality and 36.5–39.8% population-reduction) in the laboratory [72 h post-application exposure interval (PAEI)] and field trails (168 h PAEI), respectively. All tested biorationals, except Methoxyfenozide [(slightly-harmful/Class-II), i.e., causing mortality of parasitoids between a range of 25–50%] and Tebufenozide [(moderately-harmful/Class-III), i.e., causing mortality of parasitoids between the ranges of 51–75%], proved harmless/Class-I biorationals at PAEI of 7-days in the field (parasitism-reduction < 25%) and 3-days in the lab (effect < 30%). In laboratory bioassays, exposure of parasitized-pseudopupae and adult-parasitoids to neem and bitter gourd oils demonstrated that these compounds proved harmless/Class-I biorationals (< 30% mortality). Alternatively, Pyriproxyfen, Buprofezin, Fenoxycarb, Methoxyfenozide, and Tebufenozide were slightly-harmful biorationals (30–79% mortality) against the respective stages ofE. formosa. We conclude that most of the tested biorationals proved harmless or slightly harmful toE. formosa, except tebufenozide after PAEI of 7-days (168 h) in the field and, therefore, may be used strategically in Integrated Pest Management (IPM) ofB. tabaci.

Considering the resistance development-potential of whitefly (Bemisia tabaci) against control tactics with limited action mechanisms, the present study investigated the accumulation of two different silicon (Si) sources (SiO₂ and K₂SiO₃) in cotton plants. The tested dose rates (0, 200, and 400 mg/L) of both Si sources were applied directly to the soil or through foliar application on cotton leaves. Moreover, a laboratory bioassay was also conducted to evaluate the performance of applied Si sources against the oviposition preference and biology of B. tabaci. A significantly higher Si accumulation, reduction in oviposition preference, and prolonged developmental period of all nymphs and total life cycle of B. tabaci was observed in the case of foliar-applied silicon. Similarly, among Si sources, a significant decline in the number of oviposited eggs and delay in the developmental period of B. tabaci was observed in the case of SiO_2, followed by K₂SiO₃. Moreover, cotton plants subjected to SiO₂ treatments possessed higher Si contents in their leaves than K₂SiO₃ treated plants. The results further revealed that both Si sources showed promising results at their higher concentrations regarding the tested parameters of Si accumulation, fecundity, and developmental period of B. tabaci. Our results strongly suggest that among emerging pest control strategies in cotton plants lies the use of foliar application of Si, which can also be incorporated in different integrated pest management programs due to its safety for humans and beneficial insect fauna.