The effect of acclimation on mating frequency and mating competitiveness in the Queensland fruit fly, Dacus tryoni, in optimal and cool mating regimes

Abstract

Mating frequency in groups of Dacus tryoni which had been either warm‐acclimated or cold‐acclimated were compared in temperature regimes ranging from just above mating‐threshold to optimal. Cold‐acclimation appeared to suppress initial mating ability of mature insects of both sexes to an extent which depended upon the acclimation regime used. The most favourable cold‐acclimation regime produced flies which in certain circumstances were able to mate at an initial frequency similar to that of warm‐acclimated flies. In no mating regime was initial mating significantly more frequent in any cold‐acclimated group than it was in any warm‐acclimated group. In most cases warm‐acclimated flies in a given regime mated at high frequency for 1–2 days, whereas the cold‐acclimated flies mated at low frequency for a greater number of days. In all cases, cold‐acclimated flies accumulated a similar or significantly lower total number of matings than warm‐acclimated groups. In experiments in which both warm‐acclimated and cold‐acclimated males competed for cold‐acclimated females, the warm‐acclimated males always out‐competed the cold‐acclimated males in two mild (near optimal) regimes. In a relatively harsh (near torpor threshold) regime, there was no significant difference in the competitive abilities of cold‐acclimated and warm‐acclimated males. The relevance of these results to possible acclimation procedures used in control campaigns involving release of sterile males is discussed.

The ecology of Bactrocera tryoni (Diptera: Tephritidae): what do we know to assist pest management?

“…Breeding can occur where daily maximum temperatures exceed 20 • C (Meats & Fay, 2000), and areas where temperatures permit fewer than three generations per year are unlikely to ever have high populations (Meats, 1981). Detailed studies have demonstrated the capacity of adult B. tryoni to rapidly acclimate to low temperatures experienced at the southern extent of their range and high altitude regions (Meats, 1976a(Meats, , b, c, 1987Meats & Fay, 1976O'Loughlin et al, 1984). In addition to plasticity in their ability to tolerate cool temperatures, adult B. tryoni populations may also exhibit adaptation to their local thermal environment.…”

Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) overwintering: an overview

“…These flies had apparently fairly recently emerged. Cool, but not cold temperatures disrupt mating, with only 10% to 15% of experimental populations mating at 18°C (Meats & Fay 1976). … As there must have been at least several thousands of maggots present in late autumn in this cage, it would seem that only a very small percentage indeed survived the winter …' 'I do not consider the overwintering of the fruit fly in the Stanthorpe district is a factor of major importance'.…”

“…Jarvis 1926 B. tryoni overwintering 5 variable, ranging from 6.8°C to 3.2°C depending on prior temperature acclimation: flies previously exposed to cold conditions had lower torpor thresholds than flies exposed to higher temperatures (Meats 1973;Meats 1976a;Meats & Fay 1976). These flies had apparently fairly recently emerged.…”

“…… As there must have been at least several thousands of maggots present in late autumn in this cage, it would seem that only a very small percentage indeed survived the winter …' 'I do not consider the overwintering of the fruit fly in the Stanthorpe district is a factor of major importance'. Jarvis 1926 B. tryoni overwintering 5 variable, ranging from 6.8°C to 3.2°C depending on prior temperature acclimation: flies previously exposed to cold conditions had lower torpor thresholds than flies exposed to higher temperatures (Meats 1973;Meats 1976a;Meats & Fay 1976). Fletcher (1975) refers to flies making local foraging flights (for food and water) in his overwintering site, which reinforces the point that flies will move during winter unless temperatures are below the flight threshold of 14-15°C (Meats 1989).…”

THE INFLUENCE OF AGE, AMBIENT TEMPERATURE, THERMAL HISTORY AND MATING HISTORY ON MATING FREQUENCY IN MALES OF THE QUEENSLAND FRUIT FLY, DACUS TRYONI

“…There can be occasions, however, in spring and autumn when dusk temperatures are near to the lower threshold for mating but when insects can also be expected to be mature (Meats & Khoo, 1976). Meats & Fay (1976) considered that it was possible that cold-acclimation with respect to mating threshold may occur so that the number of occasions that mating was possible would be increased or that mating frequency in the range of temperatures just above the threshold would be increased. Their laboratory tests, however, found that thermal history had no significant effect on mating frequency at test temperatures down to 18 ~ which is just above the threshold.…”