Effect of Temperature on Time to Eclosion and Spring Emergence of Postdiapausing Horn Flies (Diptera: Muscidae)

Abstract

The effect of temperature on postdiapause eclosion of horn flies, Haematobia irritans (L.), was examined in the laboratory and field. Pupae stored at -5, 0.5, 5. and 10°C completed diapause development after 98, 84, 42, and 56 d. Median time to eclosion of diapause-completed flies was ≤10.5 d at 25°C, Pupae placed under pats in the fall for various periods were retrieved and reared at 15°C, 20, 25, and 30°C, Time to eclosion was significantly influenced by rearing temperature following retrieval from the field, and decreased with length of time outdoors. An equation was developed describing the influence of temperature on the proportion of postdiapause development completed per day. The relationship between cumulative postdiapause physiological age and cumulative proportion eclosion was also determined. These relationships were used to successfully simulate spring emergence using either manure pat temperatures or air temperatures as input variables. Manure pat temperatures during the winter were considerably more stable than air temperatures and may act to intensify diapause in the fall, maximize the rate of diapause development during the winter, and prevent premature eclosion in the spring.