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United States Department of Agriculture

Agricultural Research Service

Title: Effect of Soil Moisture on Development of Diaprepes Abbreviatus (Coleoptera: Cuculionidae).

Authors
item Lapointe, Stephen
item Shapiro, Jeffrey

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 1, 1998
Publication Date: N/A

Interpretive Summary: Efforts to control the citrus root weevil, Diaprepes abbreviatus, are hindered by a lack of knowledge of its developmental biology and physiology. Rearing of the insect for experimentation and for production of natural enemies is hampered by poor understanding of temperature and humidity conditions required for optimal development. We determined the conditions of soil moisture to optimize production of adult citrus root weevils in a laboratory colony. Larvae were reared on artificial diet and then placed in soil with water content ranging from 20% to 80%. Optimal soil moisture content for pupation was 60%. When 68 day old larvae were transferred from artificial diet to soil with these moisture levels and constant temperatures, the development time from neonate to pupa was 126 days. When larvae were taken from diet and placed in soil, the proportion that pupated varied with moisture content. Low (20% to 40%) and high (80%) moisture content resulted in increased mortality, and fewest larvae pupated within the low range. The average number of days to pupation of 68 day old larvae was 58.2 days.

Technical Abstract: We conducted trials to determine conditions of soil moisture required to optimize production of adults of Diaprepes abbreviatus (L.) in a laboratory colony. Larvae of D. abbreviatus were reared on artificial diet and then placed in soil with water content ranging from 20% to 80%. Optimal moisture content of soil for pupation was determined to be 60% +/- 10% by weight. When 68 d old larvae were transferred from artificial diet to soil with these moisture levels and constant temperature (25C), mean (+/- SEM) development time of D. abbreviatus from neonate to pupa was 126 +/- 2.3 d (n = 47). For all pupae, the time required for pupation did not vary with soil moisture. When 68 d old larvae were taken from diet and placed in soil, the proportion that pupated varied with moisture content. Low (20% to 40%) and high (80%) moisture content resulted in increased mortality, and fewest larvae pupated within the low range. The mean +/- SEM number of days to pupation of 68 d old larvae was 58.2 +/- 2.3 (n = 47). Older (180 d) larvae reared on diet pupated over a greater range of moisture treatments (30% - 70%) and were adversely affected only by the highest (80%) and lowest (20%) treatments. Mean +/- SEM time to pupation (38.4 ñ 1.9 d, n = 54) did not vary for 180 d old larvae kept at 30% - 70% moisture content. A continous colony of D. abbreviatus has been maintained at the U.S. Horticultural Research Laboratory at Orlando, FL, since 1992.

Last Modified: 12/22/2014
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