|Medrano, Enrique - Gino|
|Bell, Alois - Al|
Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2011
Publication Date: 9/1/2011
Citation: Medrano, E.G., Esquivel, J.F., Bell, A.A., Greene, J.K., Roberts, P.M., Bacheler, J.S., Marois, J.J., Wright, D.L., Nichols, R.L. 2011. Analysis of microscopic cotton boll feeding injuries caused by southern green stink bug (Hemiptera: Pentatomidae). Southwestern Entomologist. 36(3):233-245. Interpretive Summary: Success of the national boll weevil, Anthonomus grandis (B.), eradication program and the use of Bt (Bacillus thuringiensis) toxin-producing cotton to control bollworm, Helicoverpa zea (B.), and tobacco budworm, Heliothis virescens (F.), has resulted in decreased insecticide applications on cotton. Consequently, pressure from other insect pests has increased resulting in a decline in cotton yield and fiber quality. Chief among these other pests are insects that feed on green developing bolls using a piercing-sucking mechanism. Visual signs of insect feeding on these bolls are not consistently detected and resulting boll rotting are often not revealed until the boll opens. We allowed the southern green stink bug, Nezara viridula (L.), a recognized boll feeding pest, to feed on green-house grown bolls. Damage to the bolls was not always visible to the naked eye. However, a microscopic examination of these bolls was able to detect insect damage. Illustrations of the detected boll injuries are provided. This is the first report to provide photographic examples of microscopic boll wall insect punctures and can serve as a guide in future work on cotton boll feeding pests.
Technical Abstract: The southern green stink bug (SGSB), Nezara viridula (L.), can transmit certain cotton pathogens into developing green bolls resulting in disease. However, detection of diseased bolls is difficult because the exterior surface of the boll carpel wall frequently has no apparent macroscopic evidence of insect feeding regardless of infection; blisters on the interior surface of the carpel wall are commonly masked by darkened necrotic tissue. Here, we focused microscopically on the inner and outer carpel of bolls pierced by laboratory-reared SGSB (n=40) that did not carry the cotton pathogen. Identification of an association between the boll wall puncture and inner carpel blisters from SGSB feeding permitted analysis of field-grown bolls for piercing wounds. This association was used to assess evidence of feeding by feral piercing-sucking pests on the interior and exterior surface of carpel walls of field-grown bolls collected from plots in North Carolina (NC), South Carolina (SC), Georgia (GA) and Florida (FL) (USA) (n=28 per state per year) during the 2008 and 2009 production seasons. A small outer boll wall puncture wound was commonly detected on both the greenhouse and field-grown bolls inspected. Samples had evidence of insect piercing on the outer boll wall and discolored seed, yet an absence of inner wall blisters. Collectively, these data showed the capacity to microscopically identify signs of piercing-sucking insect feeding on the outer boll wall. Inner boll wall warts associated with stink bug feeding were not detected in greenhouse-grown bolls and were sporadically detected in field-collected samples. This is the first study to microscopically illustrate examples of boll wall damage caused by stink bug feeding.