Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/26/2019
Publication Date: 12/3/2019
Citation: Esquivel, J.F., Medrano, E.G. 2019. Transmission of Eremothecium coryli (syn. Nematospora coryli) to consecutive cotton bolls by individual stink bugs. Southwestern Entomologist. 44(4):853-860. https://doi.org/10.3958/059.044.0414.
Interpretive Summary: Cotton is a high-value commodity worldwide and is continually under attack by insects such as stink bugs. In earlier work, we demonstrated that stink bugs could transmit pathogens, such as bacteria and fungi, that caused rotting of the cotton seed and lint, thereby potentially reducing cotton yields and lint quality. However, it was unknown whether a single stink bug could infect multiple cotton bolls. We fed stink bugs a known fungal pathogen and caged each stink bug individually on five separate bolls in succession to determine how many consecutive bolls each stink bug could infect. Our findings revealed that some stink bugs could infect at least five bolls in succession. The ability of stink bugs to infect multiple cotton bolls may warrant re-evaluation of treatment thresholds and management tactics for this significant pest of cotton.
Technical Abstract: Cotton is a high value cash crop that is persistently plagued by insect pests such as stink bugs and related species. Stink bugs are known to vector pathogens that inflict necrosis of the cotton seed and lint, yet the frequency of pathogen transmission into successive bolls by individual stink bugs is undocumented. Individual southern green stink bug [Nezara viridula (L.)] adults (n = 80) were provided green beans (Phaseolus vulgaris L.) infected with the fungus Eremothecium coryli (Peglion) Kurtzman (syn. Nematospora coryli Peglion) and then caged sequentially with five bolls of known age to determine potential for infection of consecutive bolls by a single stink bug. Stink bug adults fed upon 82.4% of bolls (n = 108) and pathogen transmission occurred on 68.5% of these bolls (n = 89). As expected, normal insect bacterial flora was detected in all bolls with evidence of insect feeding. Overall insect feeding frequency ranged from 1 to 5 bolls per stink bug; more importantly, the frequency of boll infection also ranged from 1 to 5 bolls per stink bug. The frequency of E. coryli infection in bolls exposed to males and females did not differ between sexes (Fisher’s Exact Test: P = 0.84) and the number of females and males infecting 1 to 5 bolls did not differ (Fisher’s Exact Test: P = 0.92). These findings can serve as an impetus for determining whether current insect management thresholds should be reconsidered given the potential for multiple boll infections by individual southern green stink bugs.