TITLE:
Field Persistence and Application Timing of Beauveria bassiana and Two Surfactants to Suppress Tarnished Plant Bug Population in Cotton
AUTHORS:
Maribel Portilla, Hamed K. Abbas, Cesare Accinelli
KEYWORDS:
Surfactants, UV Light, Microbial Control, B. bassiana, Lygus
JOURNAL NAME:
Agricultural Sciences,
Vol.17 No.9,
September
24,
2026
ABSTRACT: A commercial and native isolates of Beauveria bassiana (Bb) and two emulsifiers, Tween-80 and starched-based sprayable bioplastic, applied at night and morning were evaluated in the field to measure the indices of damage caused by the tarnished plant bug (TPB), Lygus lineolaris (Palisot de Beauvois) on cotton. Effects of solar radiation on TPB suppression, infectivity, and Bb sporulation were also examined. The TPB population was significantly reduced 7 days after spray (DAS) for all treated plots, suppressing population from 5-6 adults/10 sweep nets (SN) to 1 adult/10-SN 3-DAS and 0-1 adults/10-SN 7-DAS for all treatments. Little to no variation was observed in TPB nymph populations between treated and untreated plots. No significant differences in adult suppression were observed between morning and night application (MA, NA). The highest mortality rates and sporulation were found in insects exposed to cotton terminals sprayed with NI8+Tween-80-NA, 0-DAS. Although, no significant differences were observed between MA and NA, mortality and sporulation were higher in plots sprayed at night. Mortality and sporulation significantly decreased by the first day of application for all treatments regardless of NA or MA corresponding to the high susceptibility of Bb to sunlight. The highest percentage retention of all first position fruiting structures was observed in plots treated with NI8 + Tween-80-MA (88.30 ± 1.41), NI8+BioPlastic-MA (90.77 ± 1.28), and NI8 + Tween-80-NA (87.60 ± 1.15). Which were significantly higher than the controls. Overall, the seasonal plant mapping provided clear evidence of damage to cotton caused by TPB and how Bb regardless of the isolate, surfactant, or timing prevents indices of cotton damage.