Transmission of cotton seed and boll rotting bacteria by the verde plant bug

Authors: GLOVER, JAMES - Texas A&M University; Medrano, Enrique; ISAKEIT, THOMAS - Texas A&M University; BREWER, MICHAEL - Texas A&M University

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/2019
Publication Date: 12/26/2019
Citation: Glover, J.P., Medrano, E.G., Isakeit, T., Brewer, M.J. 2019. Transmission of cotton seed and boll rotting bacteria by the verde plant bug. Journal of Economic Entomology. 113(2):793-799. https://doi.org/10.1093/jee/toz334.
DOI: https://doi.org/10.1093/jee/toz334

Interpretive Summary: The verde plant bug has become a major pest of cotton along the coastal region of South Texas; yield losses in the production area to boll rotting diseases have also increased over the years. In earlier work we demonstrated that stink bugs, which possess a needle-like feeding apparatus similar to verde plant bugs, were major vectors of boll rot pathogens that caused inner rotting of cotton bolls. In this study, we exposed verde plant bugs to a known bacterial boll rotting pathogen and caged the bugs on bolls to determine their ability to transmit the boll rot pathogen. Our results showed that the effects of feeding by those bugs that carry and transmit the infectious agent could lead to complete internal rotting of the boll. In contrast, verde plant bugs that were not carrying the pathogen produced only slight localized damage to the cotton lint at the feeding site. Based on photographic evidence and our experimental data, our findings suggest verde plant bugs likely play a major role in the yield losses attributed to boll rot diseases that have been observed in South Texas over the years.

Technical Abstract: Field experiments and supporting laboratory work were conducted to characterize the ability of the verde plant bug, Creontiades signatus (Distant) (Hemiptera: Miridae), a boll-feeding sucking bug, to vector a cotton seed and boll rot bacterial pathogen, Serratia marcescens (Bizio) (Enterobacteriales: Enterobacteriaceae). A S. marcescens strain was originally isolated from bolls infested with verde plant bug in south Texas. A rifampicin resistant (Rifr) S. marcescens variant (labeled CC119-R) was spontaneously generated for tracking and used in transmission and retention experiments. Serratia-exposed and non-exposed adult verde plant bugs from a laboratory colony were placed individually on 5, 6, 7, and 8 day old bolls (post-anthesis). The bacterial infection process did not apparently affect insect vigor based on similar average boll injury ratings observed across both exposed and non-exposed bugs. Cotton bolls caged with Serratia-exposed verde plant bugs had a significantly greater presence of Serratia that were Rifr and cotton boll rot symptoms than bolls caged without bugs (no-insect controls) or non-exposed bugs. Transmission of the disease agent by verde plant bug was visually observed, recovered, and confirmed across all boll ages assayed. Incidence of diseased locules on 5 and 6 day old bolls was the same or greater than on 7 and 8 day old bolls. Verde plant bug was able to harbor the disease agent anywhere from 24h up to 96h post-infection, and transmission efficiency rates ranged from 54% to 62% across initial transmission and retention (transmission across two bolls fed upon consecutively) studies. Along with photographic evidence, the experimental data supported that boll damage associated with verde plant bug infestations was likely in good part dependent on verde plant bug transmitting the cotton pathogen S. marcescens.