Pollen contamination of boll weevil traps

Authors: Jones, Gretchen; Greenberg, Shoil

Submitted to: Grana
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/22/2009
Publication Date: 9/21/2009
Citation: Jones, G.D., Greenberg, S.M. 2009. Pollen contamination of boll weevil traps. Grana. 48:297-309.

Interpretive Summary: The boll weevil has been one of the most devastating insect pests of cotton in the southern U.S. Weevils were long thought to feed only on cotton flowers, fruit, and pollen, but pollen from numerous other plant taxa have been identified recently on captured weevils. Some of the non-cotton plant taxa may be contaminants rather than food sources. The purpose of this research was to quantify the pollen contamination of boll weevil traps placed in the Lower Rio Grande Valley of Texas, near Brownsville, near Weslaco, and in the Santa Ana Wildlife Refuge from January thru April. Traps located near Brownsville and Weslaco contained the least amount of pollen and the lowest pollen diversity, and traps at the Santa Ana Wildlife Refuge contained the greatest pollen diversity (51 plant taxa). More pollen was found on the trap skirt than on any other part of the trap, and the trap's mesh top under the plastic lid contained the least amount of pollen (and no pollen in many cases). The results indicate that it is doubtful that adult weevils become contaminated with pollen while inside the trap.

Technical Abstract: During the Twentieth Century, the boll weevil, Anthonomus grandis Boheman, was the most devastating insect pest of cotton, Gossypium hirsutum C. Linnaeus, in the southern United States of America (U.S.A.). Although thought to feed only on cotton, the list of non-cotton alternative food sources increases yearly. Some of the listed taxa are insect pollinated while others are wind-pollinated. Wind pollinated taxa are thought to be contaminates and not actual food sources. The purpose of this research was to examine the pollen contamination of boll weevil traps. Between January and April, weevil traps were placed within the Lower Rio Grande Valley of Texas, near Brownsville, near Weslaco (a substitute location) and in Santa Ana Wildlife Refuge. A single trap was examined monthly at Brownsville and later at Weslaco. Two traps per month were examined at Santa Ana. Pollen was removed from the different trap parts (pole, skirt, mesh top, and lid) by wiping them with an individual, sterile, 100% cellulose acetate filter. The original trap was replaced with a cleaned trap. The replacement trap was left for three days and then wiped for pollen. Traps located near Brownsville and Weslaco contained the least amount of pollen and the lowest pollen diversity. Traps at Santa Ana contained the greatest pollen diversity. Overall, 469 pollen grains representing 51 taxa were counted from the two traps at Santa Ana. More pollen was found on the skirt than any other trap part regardless of the site. The mesh top contained the least amount of pollen. From these data, it is doubtful that adult weevils become contaminated with pollen while sitting in the trap. More research is needed to examine pollen transfer among trapped weevils and the longevity of the contaminated pollen.