Localization of selected pathogens of cotton within the southern green stink bug

Abstract

Southern green stink bugs, Nezara viridula (L.) (Hemiptera: Pentatomidae), are pests of cotton recently shown to ingest, retain, and introduce some pathogens of cotton into bolls. The objective of this study was to determine where pathogen colonization occurs in N. viridula after ingestion. Laboratory‐reared adult N. viridula were fed sterile green beans soaked in water (control) or beans previously soaked in a suspension of one of three opportunistic bacterial pathogens [Pantoea agglomerans (Ewing & Fife), Pantoea ananatis (Serrano) Truper & De’Clari, or Klebsiella pneumoniae (Schroeter)] or a yeast [Nematospora coryli (Peglion)]. The insect rostrum, head, and alimentary canal were subsequently processed to determine the presence of pathogenic organisms. Overall, the alimentary canal exhibited significantly more bacterial colony forming units per g tissue (mean ± SEM = 4 806.3 ± 397.2) than the head (443.4 ± 397.2) and rostrum (46.0 ± 397.2); concentrations in the head and rostrum did not differ significantly. All four pathogens were detected in the alimentary canal, but only P. agglomerans and N. coryli were detected in the rostrum and head. Although P. ananatis and K. pneumoniae were only detected in the alimentary canal, their ranges of concentrations were similar to those of P. agglomerans and N. coryli in this tissue. Non‐selective media indicated that other bacterial fauna was also detected in all study insects. Thus, N. viridula does not discriminate with regard to ingestion of pathogens. The observed distribution pattern of tested bacteria and yeast in certain tissues of N. viridula clarifies the propensity for transmission of P. agglomerans and N. coryli. Results are discussed in relation to future research avenues examining selective colonization of certain pathogens and frequency of host infection by adults harboring the pathogenic organisms.

Ingestion of a Marked Bacterial Pathogen of Cotton Conclusively Demonstrates Feeding by First Instar Southern Green Stink Bug (Hemiptera: Pentatomidae): Table 1.

“…However, detection of the marked bacteria and general bacteria in similar quantities in each of the stadia suggested that the marked bacteria were able to colonize the insect without compromising the general bacterial fauna. Esquivel and Medrano (2012) also observed similar densities of marked bacteria and innate bacteria in alimentary canal of adults. Therefore, a competitive exclusionary effect for colonizing the insect likely does not exist between the introduced marked bacteria and innate bacterial fauna.…”

Retention of Pantoea agglomerans Sc1R across stadia of the southern green stink bug, Nezara viridula (L.) (Hemiptera: Pentatomidae)

“…Thus, in the current study, P. agglomerans Sc1R (and innate microbiota) cells evidently were residing in the midgut of the various stadia. Although, previous work showed that, in adult N. viridula, P. agglomerans Sc1R can also colonize in the rostrum and the head [10].…”

“…The food items were replaced twice per week at 3-4 d intervals. Also, at each food replacement, available egg clutches were harvested and placed in modified plastic containers as previously described [10], Esquivel & Medrano (2012). Nymphs resulting from these egg clutches and colony insects were held in a walk-in environmental chamber at 26.7±1.0˚C and 14:10 [L:D] photoperiod.…”

Endophytic fungi alter sucking bug responses to cotton reproductive structures

“…Herbivorous sucking bugs often feed upon plant reproductive structures and can therefore directly impact plant fitness and crop yields. Many sucking bugs such as the plant bugs (Miridae) and stink bugs (Pentatomidae) can be major agricultural pests because of their impact on plants either directly through feeding damage or indirectly by vectoring plant pathogens (Greene et al ., ; Esquivel & Mowery, ; Esquivel et al ., ; Brewer et al ., ; Esquivel & Medrano, ). In cotton, the relatively recent rise of plant bugs and stink bugs as pests is attributed in part to decreased application of broad‐spectrum insecticides, because of the use of Bt plants targeting caterpillars (Zhao et al ., ) and successful pest mitigation strategies such as the boll weevil eradication program (Smith, ; Allen, ; Deguine et al ., ).…”