ECOLOGICALLY-BASED MANAGEMENT OF BOLL WEEVILS AND POST-ERADICATION CROP PESTS
Location: Areawide Pest Management Research
Title: Response of cotton squares to various boll weevil oviposition puncture types
Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: February 1, 2010
Publication Date: April 19, 2010
Citation: Esquivel, J.F. 2010. Response of cotton squares to various boll weevil oviposition puncture types. National Cotton Council Beltwide Cotton Conference. p. 999-1003.
Interpretive Summary: Boll weevils lay eggs in cotton flower buds and produce different puncture types including unsealed punctures, punctures sealed with frass (frass-sealed), punctures sealed with a wax film (wax-sealed), and punctures sealed with a wax film plus frass (wax-sealed plus frass). It is traditionally accepted that frass-sealed punctures accompanied by a natural plant response, commonly referred to as a nipple, indicate where an egg has been laid. This study was conducted to determine whether the differing puncture types would produce a plant response (or nipple), and determine the time required for a plant response to develop. All puncture types produced a plant response. Frass-sealed punctures were more abundant. A similar frequency of egg-laying was seen in puncture types covered by seals. The overall percentage of sealed punctures that produced a nipple while containing eggs was less than 37%. Within 24 hours of egg lay, over 90% of punctures containing eggs had yet to produce a nipple. These results clearly indicate that different puncture types containing eggs do produce nipples but require 48 – 72 hours to appear in most of the punctures. These results can be used in conjunction with the traditional method of locating boll weevil eggs and help in detection of reproducing boll weevil populations.
In an earlier laboratory study, estimates for boll weevil oviposition in unsealed punctures, punctures sealed with frass (frass-sealed), punctures sealed with a wax film (wax-sealed), and punctures sealed with a wax film plus frass (wax-sealed plus frass) were determined. However, the traditional protuberances of tissue commonly associated with boll weevil oviposition sites were not observed. This study was conducted to determine whether these differing oviposition puncture types would elicit a plant response (i.e., protuberance of tissue at the location of the puncture site) from cotton squares, and, if so, examine the developmental rate of the plant response. All puncture types did elicit a plant response, but the response was not limited to infested punctures (containing eggs and/or larva). Frass-sealed punctures were predominant but other sealed puncture types exhibited comparable infestation rates (82-93%). Despite the high infestation rates in sealed punctures, the overall percentage of infested punctures exhibiting a plant response was only 37.3, 25.7, and 15.3% for frass-sealed, wax-sealed, and wax-sealed plus frass, respectively. Some protuberances were observed at punctures aged =24 h, but ˜93% of infested punctures at 24 h had yet to produce a plant response. Punctures that were 48 and 72 h old reflected more protuberances. Data presented here indicated that differing infested puncture types (i.e., wax-sealed, wax-sealed plus frass, and unsealed) do indeed elicit protuberances but require 48 – 72 h to appear in a majority of punctures. These results can supplement the traditional method of detecting oviposition and aid in detection of reproductive boll weevil populations.