Evaluation of the entomopathogenic Beauveria bassiana and conventional insecticides to control Lygus lineolaris in cotton

Authors: Portilla, Maribel; Little, Nathan; Elkins, Blake; Du, Yuzhe; ZHU, YU-CHENG - US Department Of Agriculture (USDA); Glover, James; Read, Quentin

Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2025
Publication Date: 6/25/2025
Citation: Portilla, M., Little, N., Elkins, B.H., Du, Y., Zhu, Y., Glover, J.P., Read, Q.D. 2025. Evaluation of the entomopathogenic Beauveria bassiana and conventional insecticides to control Lygus lineolaris in cotton. Southwestern Entomologist. 50(2):611-631. https://doi.org/10.3958/059.050.0225.
DOI: https://doi.org/10.3958/059.050.0225

Interpretive Summary: This investigation demonstrated that the efficacy of both Beauveria bassiana and insecticide applications on tarnished plant bug control can vary between sprays. These variations could be caused by a variety of factors, including agroecosystem, climatic adverse, machinery applications or in the case of B. bassiana, technical powder production. All these factors cannot be avoided, but it was possible to ensure homogeneity in the bioassay execution with low or no mortality found in untreated control. Overall, the positive or negative efficacy of B. bassiana or insecticide sprays on arthropod pests in the field is speculative. However, the interaction among environmental variables such as solar radiation, temperature, and relative humidity are the main factors for entomopathogenic fungi, while for insecticides are rainfall and wind. In general, entomopathogenic fungi like B. bassiana will not supplant the need for chemical insecticides in cotton or any field crop production system, and the idea is to expand its potential to be incorporated into modern integrated pest management control programs.

Technical Abstract: The efficacy of the native strain NI8, Beauveria bassiana (Balsamo) Vuillemin and set of insecticides (imidacloprid, sulfoxaflor, novaluron, and acephate) to control the tarnished plant bug (TPB), Lygus lineolaris (Palisot de Beauvois) was evaluated. The effect on cotton production was also examined. This study was conducted over two years under field and laboratory conditions. The effectiveness was determined by applying each treatment on cotton field plots. Mortality of TPB adults was greatest for those placed on leaves sprayed with acephate (41±2.7 and 40±2.5 [SE]) 3-days post exposure (DPE) for 2015 and 2016, respectively, reaching 78±5.0 and 68±3.0 10-DPE each year; which was highly significant different when compared with mortality of TPB exposed to leaves sprayed with B. bassiana 10-DPE for both years (32±3.0 and 35±3.7, respectively). There were no significant differences in TPB mortality between B. bassiana, imidacloprid, sulfoxaflor, and sulfoxaflor + novaluron 10-DAE for 2015. However, there were highly significant differences among those treatments for 2016, which was reflected in the cotton yield per harvested plot. Plots sprayed with B. bassiana (1,250±80 SD lb/acre) showed no significant differences among plots sprayed with the set of insecticides (1,375±81 lb/acre), but there were significant differences compared to control (1,116±66 lb/acre) for 2015. Unexpectedly, little to no variation was observed in cotton yield between B. bassiana and untreated plots (812±27 and 810±39 lb/acre, respectively) for 2016. Overall, these results indicated that B. bassiana controls the TPB population as well as some synthetic insecticides. However, its performance could vary between applications, which could be affected most likely by environmental factors. In general, acephate performs superiorly in TPB control.