Larval-pupal mortality of Mediterranean fruit fly (Diptera: Tephritidae) from interaction of soil, moisture, and temperature

Survival of Ceratitis capitata (Wiedemann) larval and pupal stages was determined in several soil types at three levels of water saturation at 15 and 25 degrees C, as well as in water. Survival was negatively correlated with the soil at bulk density but positively, with percentage of porous space and percentage of water saturation. Temperature and soil texture both interacted with moisture to give the lowest emergence from dry soils with high bulk density at 15 degrees C. Larvae submerged under water survived up to 4 d and pupae, 3 d. When submerged, intermittently for 9 and 12 daily, 65% of 3rd instar larvae and 17% of pupae, respectively, survived to emerge as adults. The pupal stage lasted 45-56 d at 15 degrees C for survivors. Mortality in wet soils was not caused by pathogenic organisms. We conclude that water loss during a lengthy pupal period at low temperature in soils with low water holding capacity during the dry season is the probable cause of pupal mortality. Anoxia, on the other hand, may be the cause of death during the rainy season in soils with high bulk densities