Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/19/2006
Publication Date: 1/31/2007
Citation: Esquivel, J.F. 2007. Evaluation of puncture types as indicators of boll weevil (Coleoptera: Curculionidae) oviposition in cotton squares. Environmental Entomology. 36:183-187.
Interpretive Summary: The boll weevil continues to be a serious pest of cotton in some regions of the Cotton Belt. Detection of reproducing weevil populations is determined by the presence of sealed punctures in cotton fruit, and it is commonly accepted that punctures sealed with excrement contain eggs. In a two-year laboratory study, the relationship between egg-laying and the different types of puncture seals was examined. Eggs were observed in 64.6 to 72.9% of punctures sealed with excrement-and-wax and excrement-alone, respectively, during 2001. During 2002, the overall observed range of egg-laying was 53.4 to 55.2% in wax-sealed and frass-and-wax-sealed punctures, respectively. However, lower percentages of egg-laying in relation to puncture type were observed in individual study replicates. Results indicate sealed punctures do not necessarily reflect egg-laying by the boll weevil. Findings indicate other puncture types can also be used, in addition to those sealed with excrement, to detect egg-laying sites. These findings impact boll weevil eradication coordinators, field consultants, and researchers that rely on accurate determination of boll weevil oviposition.
Technical Abstract: The relationship between boll weevil puncture types and oviposition was examined in laboratory studies during 2001 and 2002. Newly eclosed females (=24 h old) were fed fresh squares daily for 8-d, and mated at 4-d of age with similar age males. Removed squares were dissected to examine oviposition in relation to individual puncture types. Puncture types were classified as: unsealed (open); puncture with frass seal; puncture with wax seal, and puncture with wax seal and partially covered with frass. Overall, no significant associations were detected between the types of sealed punctures and the frequency of oviposition. The overall frequency of oviposition in sealed punctures ranged from 64.6 (wax-seal with frass) - 72.9% (frass-sealed) during 2001, and 53.4 (wax-sealed) - 55.2% (wax-seal with frass) during 2002. However, examination of individual trials revealed the variability in oviposition associated with sealed puncture types, and an observed low oviposition frequency of 33.3% in wax-seal with frass punctures during 2001. Data presented here describes the relationship between various puncture types and boll weevil oviposition and indicate that sealed punctures do not necessarily reflect oviposition. Implications of the need for accurate determination of boll weevil oviposition in field situations and future fecundity studies are also discussed.