Effect of soil moisture on development of Diaprepes abbreviatus (Coleoptera: Curculionidae)

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 a commercially available 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 (20-40%) 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 1.9 d, n = 54) did not vary for 180-d-old larvae kept at 30-70% moisture content.