Effect of Soil Temperature and Moisture on Survival of Eggs and First-Instar Larvae of Delia radicum

Abstract

Edaphic factors such as soil temperature and moisture influence soil-dwelling insects, whose most vulnerable stages typically are eggs and young larvae. In this study, the survival of eggs and first-instar larvae of the cabbage maggot, Delia radicum L., was measured under laboratory conditions after exposure to a range of soil temperatures and moistures. When eggs were exposed to constant temperature (20-29°C) and humidity (5-200% [wt:wt]), temperature had no significant effect on survival, whereas humidity <25% [wt:wt] caused egg mortality. The gradual exposure of eggs to high temperatures resulted in low mortality below 33°C, but <5% of eggs survived at 40°C. When first-instar larvae were exposed to constant temperature (17-29°C) and humidity (5-100% [wt:wt]), both factors as well as their interaction had a significant effect on larval survival, which was nil at 5% (wt:wt) for all temperatures but increased from 21.9 to 42.8% at 17°C and from 34.1 to 55.0% at 29°C, for soil moisture contents of 15% and 100% (wt:wt), respectively. Eggs of D. radicum are resistant to low soil moisture and high temperature conditions. Larval survival tends to increase with an increase in soil temperature and moisture. It is suggested that soil temperature be integrated into insect development simulation models instead of air temperature, to build more effective models for cabbage maggot management.

Oviposition Pattern of Early and Late-Emerging Genotypes ofDelia radicum(Diptera: Anthomyiidae) at Different Temperatures

“…Egg mortality was also relatively constant (Ϸ11%) with temperature. Different results were obtained for larvae survival, which tends to increase with an increase in soil temperature and moisture (Lepage et al 2012). Immature stages that hatched from eggs of both the early and late-emerging genotypes had the same probability of survival.…”

Abiotic effects on the distributions of major insect species in agricultural fields

“…; Lepage et al . ). Our results implied that there were variations in the relationships to climate among different species of Diptera.…”

Seasonal Flight, Optimal Timing and Efficacy of Selected Insecticides for Cabbage Maggot (Delia radicum L., Diptera: Anthomyiidae) Control

“…Bligaard [ 31 ] reported that the percentage of mortality of eggs and larvae is very high (between 47% and 61%). Eggs of D. radicum are resistant to low soil moisture and high temperature conditions, while larval survival tends to increase with an increase in soil temperature up to 33 °C and in the and moisture [ 32 ]. Climatic conditions during the period of egg laying and larval development (April and May) in 2011 were similar to those observed in the other three years, which supports the idea that the absence of wilting symptoms was due to other factors.…”

“…Climatic conditions during the period of egg laying and larval development (April and May) in 2011 were similar to those observed in the other three years, which supports the idea that the absence of wilting symptoms was due to other factors. In May of 2011 the amount of precipitation was the highest among all experimental years, and this may have influenced larval survival [ 32 ]. Several authors [ 8 , 33 , 34 ] have suggested that some of the 60–100 species of carabid and staphylinid beetles found commonly in cultivated soils are important predators or parasitoids of the cabbage maggot and that their activity is related to crop rotation and cultivation practices.…”