Timing of Pupation of Inopus rubriceps (Macquart) (Diptera: Stratiomyidae) in Sugarcane Fields

Abstract

Larvae of sugarcane soldier fly, Inopus rubriceps, pupated during autumn in sugarcane fields. Under conditions of moist soil and good cane growth, pupation occurred about 1 month later in northern and central Queensland than in southern Queensland and northern New South Wales, and this was related to soil temperature. The midpoint of the pupation period coincided with mean soil temperatures of 20-25 "C in each area. A laboratory experiment showed that pupation was inhibited at 25 "C and favoured by lower temperatures. The timing of pupation varied between years in one canefield in southern Queensland. Late pupation in 1991 was associated with small average size of larvae in early autumn and with dry soil conditions and poor cane growth. A high proportion of larvae failed to pupate before winter in this field in 1991. In normal years this carryover of larvae into winter was only about 10%. Male pupae were smaller than female pupae. Pupal weights were similar in each of the areas and years studied, but in some fields pupal weights declined with time during the pupation period.