Field Evaluation of Beauveria bassiana and Novaluron Alone and Combined, versus Conventional Insecticides to Control Lygus lineolaris in Cotton

Abstract

This study examined the efficacy of a native strain of Beauveria bassiana ( Bb ) (Balsamo) Vuillemin alone and in combination with the insect growth regulator (IGR) novaluron, as well as a set of insecticides, also tested individually and in combination for suppressing population of tarnished plant bug (TPB), Lygus lineolaris (Palisot de Beauvois) and evaluating the effect on cotton. The suppression of TPB was significantly different among treatments for plots sprayed with tank-mixed of bifenthrim + novaluron + acephate for both years. No significant differences were observed between single or two tank-mixed synthetic insecticides (imidacloprid or sulfoxaflor or befenbrin + novaluron) compared with novaluron alone or novaluron + Bb , except for imidacloprid when the second spray was 7D after the first spray. Control and Bb alone had the lowest population suppression at all evaluation times regardless of sprays and years. This was reflected in the cotton lint yield per harvested plot, where Bb (411 ± 230 and 533 ± 58-SD kg/ha) showed no significant differences among control (487 ± 152 and 446 ± 42-SD kg/ha) with the lowest production between treatments for the years of 2018 and 2019, respectively. No significant differences in lint yield were observed between the plots spray with the set of synthetic insecticides, (919 ± 250 and 1178 ± 38-SD Kg/ha), novaluron alone (919 ± 265 and 882 ± 29-SD Kg/ha), and novaluron + Bb (899 ± 105 and 1061 ± 46-SD Kg/ha) for 2018 and 2019, respectively. These results indicated that IGR novaluron, alone and in combination with Bb , could suppress TPB population as effectively as synthetic insecticides. Bb alone could suppress populations of nymphs compared to the control; however, its performance was not enough to prevent cotton damage and affect lint cotton yields.