Winter Mortality of Boll Weevils in Bolls and Spring Emergence in Arizona

L.A. Bariola, T.J. Henneberry, and T. Meng


 
ABSTRACT

Boll weevils, Anthonomous grandis Boheman, are known to successfully overwinter within bolls in Arizona and emerge in the spring to initiate new infestations. Certain cultural practices, such as burial of bolls and irrigation, are known to decrease survival and emergence. Tests were conducted to determine the emergence pattern of boll weevils from bolls and document the mortality of boll weevils in bolls during the winter and spring. Bolls from boll weevil-infested fields were collected during October and November 1988. Seven treatments were set-up in mid-January with 24 replications of 100 bolls each. Treatments 1-5 were contained in ventilated plastic (sweater) boxes housed at ambient temperatures in a screened insectary as follows: 1) untreated check, not buried and not watered, 2) buried under vermiculite and kept dry, 3) buried under vermiculite and watered weekly, 4) buried under soil and kept dry and, 5) buried under soil and watered weekly. Treatments 6 and 7 were buried under soil within emergence cages in the field and exposed to natural rainfall and atmospheric conditions. Treatment 6 was not watered. Treatment 7 was watered weekly. Ten bolls were collected randomly from each replication monthly and dissected to determine mortality. Results showed that weekly irrigations accelerated early spring emergence and mortality. Emergence was complete by March 29 in the irrigated treatments, but emergence continued until June 1 in the dry treatments. No live weevils were found in bolls from the irrigated treatments after May 2. The emergence and mortality patterns under simulated irrigation conditions suggest that mortality may be enhanced considerably through post-harvest irrigations which tend to crust and seal the soil surface thereby increasing soil moisture, accelerating boll rot, and hindering emergence.



Reprinted from 1990 Proceedings: Beltwide Cotton Production Research Conferences pg. 299
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998