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The use of bio-pesticides is the potential alternate of synthetic residual insecticides to cope with the problem of resistance among different insect pests while posing no threats to the environment and biological control agents. Laboratory trials were conducted in the Microbial Control Laboratory, Department of Entomology, University of Agriculture, Faisalabad (UAF), Pakistan, during 2017-18 to investigate the effect of Beauveria bassiana (Balsamo) Vuillemin (1.8 x 107 and 1.8 x 108 conidia/ml) and Bacillus thuringiensis (Berliner) at a dose rate of (0.5 and 1 µg/g) alone and in combination against fifth and sixth larval instars of Rhynchophorus ferrugineus Olivier (Curculionidae: Coleoptera). The insects were exposed to fungal and bacterial treatments by larval immersion and diet incorporation method, respectively. Results revealed that the combined application ofB. bassiana at the rate of 1.8 x 108 conidia/ml and B. thuringiensis at 0.5 and 1 µg/g exhibited synergistic effects, while combination of lower fungal concentration with both dose rates of B. thuringiensis showed additive effect against target instars of R. ferrugineus. Moreover, the mortality data showed that fifth instar larvae were more susceptible to microbial treatments than sixth instar. Maximum mycosis and sporulation was recorded in the cadavers of R. ferrugineus where B. bassiana was applied individually at dose rate of 1.8 x 107 conidia/ml. The present work suggests that B. bassiana in combination with B. thuringiensis could be a cost-benefit strategy against R. ferrugineus on date palms. [ABSTRACT FROM AUTHOR]

To investigate fluctuation in susceptibility to insecticides in the field, natural populations of Helicoverpa armigera were collected from the same field in the region of Multan, Pakistan in 2002 and 2003. The populations were examined against pyrethroids (viz. cypermethrin, esfenvalerate and fenpropathrin) and new insecticides (viz. spinosad, abamectin and indoxacarb). In 2002, the resistance ratio (RR) of cypermethrin and esfenvalerate was significantly higher than fenpropahrin compared with susceptible population. The susceptibility to cypermethrin, esfenvalerate and fenpropathrin increased significantly in 2003; however, the RR for cypermethrin was about half the RR (38) of esfenvalerate (101) and fenpropathrin (89). The toxicity of spinosad, abamectin and indoxacarb was identical in both years. In the field experiments, abamectin was more effective than other compounds tested whereas fenpropathrin, cypermethrin and esfenvalerate had similar toxicity. These results might have important implications in resistance management and suggest that the rotational use of spinosad, abamectin and indoxacarb could help to avoid the development of multiple resistant in H. armigera. [ABSTRACT FROM AUTHOR]

Field efficacies of two insect growth regulators (IGRs) at two recommended application rates, buprofezin at 370 and 555 g Al ha-1 and lufenuron at 37 and 49 g Al ha-1, were determined against the sweet potato whitefly, Bemisia tabaci (Gennadius), and the cotton bollworm, Helicoverpa armigera (Hubner), in experimental plots of cotton at the Directorate of Cotton Research, Faisalabad, Pakistan. Adverse effects of the IGRs on populations of associated arthropod predators, namely geocorids, chrysopids, coccineffids, formicids and arachnids, were also assessed. Both IGRs significantly reduced populations of B. tabaci at each application rate 24, 48 and 72 h after treatment, and higher doses were more effective than lower doses. Buprofezin was not effective against H. armigera at any tested dose for any time of treatment in any spray. Lufenuron applied at 37 and 49 g Al ha-1 effectively suppressed H. armigera populations, resulting in significant reductions in crop damage. At lower doses, both IGRs appeared safe to predator populations, which did not differ significantly in IGR-treated versus untreated control plots. Population densities of formicids and coccineffids were significantly lower at high concentrations of both IGRs in treatment plots, possibly as a result of reduced prey availability. The potential role of buprofezin and lufenuron for control of B. tabaci and H. armigera in a spray programme and the likelihood of direct toxic effects of IGRs on predatory fauna of cotton are discussed. [ABSTRACT FROM AUTHOR]