Cotton pollen retention in boll weevils, a laboratory experiment

Authors: Jones, Gretchen; Greenberg, Shoil

Submitted to: Palynology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/25/2008
Publication Date: 12/10/2009
Citation: Jones, G.D., Greenberg, S.M. 2009. Cotton pollen retention in boll weevils, a laboratory experiment. Palynology. 33:157-165.

Interpretive Summary: The Boll Weevil Eradication Program has successfully eliminated the weevil from most of the Cotton Belt in the U.S., but new techniques are needed to identify sources of re-infestations. Analysis of pollen (food) in the gut of the weevil represents a technique that may be useful in identifying the maximum time and distance over which an infesting weevil has dispersed. After feeding on cotton pollen and water in the laboratory for seven days, whole cotton pollen grains were found in the weevil gut for at least 24 hours, but the cotton pollen grains were broken after 48 hours. These results indicate that when whole cotton pollen grains are found, weevils would have fed on cotton (and possibly dispersed) within 24 hours. When only broken grains are found, weevils would have fed on cotton and may have dispersed as much as 96 hours earlier. Analysis of the longevity and condition of pollen in the weevil gut provides a valuable clue in identifying sources of weevil re-infestations, which can aid Eradication Program managers in efficiently targeting eradication activities.

Technical Abstract: Cotton pollen is thought to exist in a boll weevil’s gut for at least 18 hours. In a controlled laboratory experiment examining non-cotton food sources, a cotton pollen grain was found in an individual boll weevil that had not fed on cotton for 120 hours. Because we believe that finding whole or broken pollen grains are valuable clues in determining when weevils are in cotton, we examined the longevity of cotton pollen in a weevil’s gut. Boll weevils were fed cotton squares and water. After seven days, the weevils were placed into cleaned cages without any food; however, they were allowed to freely drink water. Weevils were examined at 0, 24, 48, 72, and 96 hours after the squares were removed. One hundred weevils were examined at each time interval. Weevils were dissected and each gut was placed onto a glass slide. Light microscopy was used to determine the presence or absence of cotton pollen. More weevils at 0 hours contained pollen (63%), than weevils at any other interval. No whole pollen grains were found in weevils after 24 h. The 96 hour time interval contained the least number of weevils with pollen (3%).