Author
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Lapointe, Stephen |
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Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 12/27/1999 Publication Date: 4/30/2000 Citation: Lapointe, S.L. 2000. Thermal requirements for development of diaprepes abbreviatus(coleoptera:curculionidae). Environmental Entomology. 29(2):150-156. Interpretive Summary: Since its introduction into the United States in 1964, the root weevil Diaprepes abbreviatus has become a major pest of citrus and ornamentals in Florida, and threatens citrus production in Texas and California. Priority-setting exercises conducted by USDA-ARS identified key research needs related to this pest. High priority was attached to gaining knowledge about the basic developmental biology of the insect. This paper completes an exhaustive study of the effects of moisture and temperature on developmental rate, pupation, and survival of immature stages of the weevil. Growth of neonate (hatchling) larvae increased exponentially with increasing temperature up to 30 deg C. However, growth rate of later instars was suppressed at 30 deg C and mortality was higher than that of larvae reared at 26 deg C. Larvae tested as late instars only (more than 56 days old) or continuously at 30 deg C, had increased mortality and produced dsmaller adults than larvae reared at 22 and 26 deg C. Larvae reared as lat instars only (more than 56 days) or continuously at 22 deg C had similar survival rates compared with those reared at 26 deg C, and they resulted in larger adults than larvae reared at 26 or 30 deg C. The time required for development from neonate to pupation was 125 days at 26 deg C. Duration of the pupal stage was inversely and linearly proportional to temperature between 22 and 30 deg C. Pupal mortality was higher at 30 deg C than at 22 or 26 deg C. The total time required for a single generation from oviposition to adult emergence at 26 deg C was estimated to be 154 days. These data help to explain the observations of adult phenology in the field and serve as baseline biological parameters for further studies into control methods. Technical Abstract: The root weevil Diaprepes abbreviatus (L.) was reared on artificial diet under controlled conditions of temperature and humidity. The lower thermal threshold for development of neonate larvae was estimated to be 15 deg C. The growth rate of neonate larvae increased exponentially with increasing temperature up to 30 deg C. However, growth rate of later instars, however rwas suppressed at 30 deg C and mortality was higher than that of larvae reared at 26 deg C. Larvae tested as late instars only (more than 56 days or continuously at 30 deg C, had increased mortality and produced smaller adults than larvae reared at 22 and 26 deg C. Larvae reared as late instar only (more than 56 days) or continuously at 22 deg C had similar survival rates compared with those reared at 26 deg C, and they resulted in larger adults than larvae reared at 26 or 30 deg C. The time required for development from neonate to pupation ranged from 125 to 128 days at 26 deg Duration of the pupal stage was inversely and linearly proportional to temperature between 22 and 30 deg C. Pupal mortality was higher at 30 deg C than at 22 or 26 deg C. The total time required for a single generation from oviposition to adult emergence at 26 deg C was estimated to be 154 day Cumulative mean air and soil temperatures and rainfall were analyzed and presented for the period October 1991 through January 1999. |
