DEPTH OF PUPATION OF CARIBBEAN FRUIT-FLY (DIPTERA, TEPHRITIDAE) IN SOILS IN THE LABORATORY

Estimates of pupation depth in soil for Caribbean fruit flies, Anastrepha suspensa (Loew), are important to future development of sampling and management techniques in fruit groves in southern Florida. Colony-reared, late third instars were placed onto soil surfaces in containers and allowed to burrow and pupate. Experimental units consisted of one larva per container. Soil in containers had a volume of 740 ml, surface area of 95 cm2, and depth of 9 cm. Pupae were excavated from soil after 72 h and their depths were recorded. Soil moisture (10 and 50% field capacity), type (muck, marl, and loam) and compaction (low and high bulk density) were the independent variables tested for their effects on pupation depth. Mean depths ranged between 0.7 cm (loam, 50% field capacity) and 3.3 cm (muck, 10% field capacity, low bulk density). Means differed significantly because of compaction and the interaction of moisture x compaction. Larvae pupated at a greater depth in soils of low compaction than in soils of high compaction. The difference in depth between low and high compaction was greater for soils of low moisture than for soils of high moisture. The pupation rate was 100% for all treatments. Mean adult emergence rates ranged between 66.7 and 100% but did not differ significantly among treatments.