Temperature-Dependent Development and Phenology of Pepper Maggots (Diptera: Tephritidae) Associated with Pepper and Horsenettle

Abstract

Emergence and developmental rates of nondiapausing pepper maggot, Zonosemata electa (Say), pupae, reared from naturally infested pepper ( Capsicum annuum L.) and horsenettle ( Solanum carolinense L.) fruit, were compared at seven constant temperatures: 5, 10, 15, 20, 25, 30, and 35°C. Pupae originating from pepper had significantly greater pupal weights and percentage of adult emergence than pupae from horsenettle. However, host plant origin, color, sex, and weight had little influence on pupal developmental times across temperatures. Nonlinear and linear models were fit to the temperature versus developmental data and used to predict adult emergence in the field. A nonlinear, four-parameter, poikilotherm model, fitted ( r2 = 0.99) to median development rates of pepper and horsenettle pupae combined, indicated that development was linear between 10 and 25°C, optimal at 26°C, and dropped to near zero at 35°C. The lower developmental threshold (± SE) for horsenettle- and pepper-reared pupae combined (9.33 ± 0.09°C)was determined by linear regression and the x intercept method. Completion of pupal development for the combined sample required 602 ± 13 degree-days (±SE) above the base temperature. Contrary to previous reports, phenology of adult pepper maggot in the field was unaffected by host plant origin. A degree-day model incorporating a 9.5°C developmental threshold and soil temperatures (10 cm depth) accurately predicted (±l d) the 50% emergence points (E 50 ) of adults reared from both host plants. A stochastic simulation model, incorporating a nonlinear developmental rate function and 2-h soil temperature records, also predicted the E 50 point accurately (±1.5 d). The simulation model accurately predicted the E 5 and E 75 to E 100 points, making it useful in management situations where emergence percentiles other than 50% are required.