The Australian fruit fly parasitoid Diachasmimorpha kraussii (Fullaway): Life history, ovipositional patterns, distribution and hosts (Hymenoptera : Braconidae : Opiinae)

Diachasmimorpha kraussii is a larval-pupal parasitoid of tephritid fruit flies in Australia. It is currently being considered for release against fruit fly pests in Hawaii. Virgin D. kraussii females lived longer (mean = 31.4 days; n = 10) than mated females (mean = 27.6 days; n = 10) by a factor of about 12%. The rate of offspring production per day by virgins (about four emerging adults per day) was the same as that of mated females, so virgins tended to produce more offspring in total (mean = 125) than did mated females (mean = 112), but the difference was not statistically significant. The time between egg deposition and emergence of the resultant adult varied from 16 days to more than 300 days, and males achieved maximum emergence before females. Adult wasps emerged at any time of the photophase, both under laboratory and field conditions, but the rate declined towards the end of the daylight period. Adult females oviposited more actively during the day than at night (30.8 vs 19 adults), and the pattern tended to be stronger when wasps were exposed to hosts initially during the scotophase (37.4 vs 18.4 adults). Mated females produced female-biased brood sex ratios of about 0.28 (proportion of males) on average, and the older the mother wasps the greater the proportion of female offspring produced. Diachasmimorpha kraussii is distributed only in northern and eastern Australia, as far south as New South Wales. It has been recorded from 13 host fly species and in association with 18 host plant species

The Australian Fruit Fly parasitoid Diachasmimorpha kraussii (Fullaway): mating behavior, modes of sexual communication and crossing tests with D. longicausdata (Ashmead) (Hymenoptera: Braconidae: Opiinae)

We describe the mating behavior of Diachasmimorpha kraussii for the first time, and confirm with cross-mating tests the separate species status of D. kraussii and D. longicaudata. Flight cage experiments suggest that mating takes place on foliage and that a distance attractant pheromone is secreted by the females, and perhaps also by the males. The most obvious aspect of the sexual interaction between males and females is the wing vibration performed by males in the nearby presence (about 1 cm) of a conspecific virgin female. Wing vibration produces an acoustic signal critical to mating success, for wingless males could seldom mate. Experimental manipulations demonstrate that males vibrate their wings in response to a chemical associated with the female, but not present in males. The chemical appears to be associated with the cuticle, as it is present (as demonstrated by male behavior) in recently-killed females, and it can be stripped from these females with acetone. The interaction proceeds only if the female is receptive (starting 6-48 h after emergence) and when she adopts a particular stance. Receptive females stand still, fold both pairs of wings over the abdomen, hold their antennae back together over their wings and allow males to mount. Males continue tapping their antennae on the females' thoraces while intromission takes place. The mating sequence of D. longicaudata is generally similar to that of D. kraussii, but individuals of the two species did not mate in small cages, which confirms their species status. In crossing tests all males vibrated their wings, indicating that the female's cuticular chemicals are similar across species. No females in mixed pairs assumed the receptive stance, suggesting the acoustic signals differ across species

Mate recognition in the South African citrus thrips Scirtothrips aurantii (Faure) and cross-mating tests with populations from Australia and South Africa

South African citrus thrips (Scirtothrips aurantii) is a pest of citrus, mango and other horticultural species in its native range, which encompasses a large part of Africa. Its adventitious establishment in Australia in 2002 was a major cause for concern. The thrips, 11 years after its incursion into Australia, has remained on plants of a single host plant genus Bryophyllum (Crassulaceae). Characterization of the Specific-Mate Recognition System of the Bryophyllum population of thrips present in Australia and behavioral bioassay experiments revealed that compounds found in the insects' body extracts play a crucial role in mate recognition of S. aurantii. Reciprocal cross-mating experiments between the Australian Bryophyllum insects and South African S. aurantii from horticultural host plants showed that mating frequencies were significantly lower in test crosses (Bryophyllum x horticultural) than in controls (Bryophyllum x Bryophyllum or horticultural x horticultural), which indicates there are at least two distinct species within S. aurantii and suggests further tests of this interpretation. The results suggest that these tiny phytophagous insects localize mates through their association with a particular host plant species (or closely-related group of species). Also, specific tests are suggested for clarifying the species status of the host-associated populations of S. aurantii in Africa