BIOLOGY OF THE PREDATORY FLY COENOSIA TIGRINA (FAB.)(DIPTERA: ANTHOMYIIDAE): REPRODUCTION, DEVELOPMENT, AND LARVAL FEEDING ON EARTHWORMS IN THE LABORATORY

Abstract

Adults of the anthomyiid Coenosia tigrina (Fab.), which are predators of flying insects including pest Diptera such as the onion maggot fly, feed on earthworms in the larval stage. The bionomics of C. tigrina females were studied in the laboratory at 15, 20, and 25°C, under different mating regimes. Adult female longevity slightly exceeded 1 month at 25°C and was close to 2 months at 15°C. Oviposition started 1–3 weeks after emergence, the delay tending to decrease with increased male presence. Females laid eggs at intervals of 1 to several days, in batches averaging 10–30 eggs depending on temperature. Fecundity reached an average of 230 eggs at 25°C with the sustained presence of males. Egg hatch decreased with the mother’s age, except when males were present for most of the female’s lifetime. Females exhibited maximal daily rate of predation at 25°C, but maximal lifetime predation was observed at 20°C. Male predation was less than females’, and female predation decreased with age. The time to eclosion decreased from 11 to 5 days as the temperature of egg incubation increased from 15 to 25°C. Larval weight at eclosion decreased with mother’s age. Postembryonic development and larval growth were studied at 15, 20, and 25°C, larvae being fed on four lumbricids. Development times decreased with increasing temperature between 15 and 25°C: from 35 to 15 days for larval development, and 28 to 12 days for pupal development. Males developed at a slower rate than females, but females weighed more at emergence. Larval survival was 30–60% on worm sections, and dropped to 17% on live mature Eisenia foetida (Sav.); but survival reached 90% on live, immature E. foetida 1–2 cm long. The larvae of C. tigrina penetrate the epidermis of earthworms, and feed internally with a preference for circulatory and chlorogogonous tissues.

Environmental factors affecting the behavior of Coenosia attenuata, a predator of Trialeurodes vaporariorum in tomato greenhouses

“…Coenosia tigrina (Fabricius) females displayed a higher frequency of predatory flights (Morris & Cloutier, 1987). Although predatory flights only accounted for around 6% of the total flights in C. attenuata, >60% of such flights resulted in successful prey capture.…”

An optimized method for mass rearing the tiger-fly, Coenosia attenuata (Diptera: Muscidae)

“…The treatment with one pair per cage gave poor results, with only 32.5% of the cages producing adults. With just one male in a cage, there may be a high risk of failure in the mating or fertilization processes, as Morris & Cloutier (1987) report that Coenosia tigrina (Fabricius, 1775) females occasionally refuse males that attempt to mate with them. In addition, 100% of the cages with 5 and 10 pairs produced tablE 3.…”

“…However, these authors record 38 days and 33 days as the maximum female and male longevity, respectively, under laboratory conditions (25°C and 50-60% RH) and an estimated longevity of eight weeks under greenhouse conditions. Our predators lived longer, possibly because they had a better food supply and the temperature was lower, since Morris & Cloutier (1987) report that C. tigrina longevity is significantly reduced by an increase in temperature, even from 20 to 25°C.…”

“…Future studies should determine the optimum ratio of males to females instead of using pairs. According to Morris & Cloutier (1987), multiple copulations are recorded for both sexes of C. tigrina and a male is able to successfully fertilize six females. Another point that needs further study is the relative merits of using an M substrate obtained by mixing soil and coconut fibre after fungus gnats have been separately added to the soil and coconut fibre versus one in which the soil and coconut fibre are mixed together before the fungus gnats are added, which avoids any potential injury to the fungus gnat larvae during the mixing process.…”

Temperature Influences on Functional Response of <I>Coenosia attenuata</I> (Diptera: Muscidae) Individuals

“…This ßy is often found in cold greenhouses where it operates as an efÞcient control agent of whiteßies at various locations in central and southern Italy (V.V., unpublished data) as well as in northern Italy (Colombo and Eö rdegh 1991). Although the immature life stages inhabit the soil where the larvae presumably feed on detritus or soil organisms of various dimensions, the adults behave like other species of the same genus and attack in ßight, ßying whiteßies and other small insects (Hobby 1931, Morris and Cloutier 1987, Drummond et al 1989, Colombo and Eö rdegh 1991.…”