First instar larvae morphology of Opiinae (Hymenoptera: Braconidae) parasitoids of Anastrepha (Diptera: Tephritidae) fruit flies. Implications for interspecific competition.

The morphology of the first instars of the Opiinae braconids Diachasmimorpha longicaudata, Doryctobracon areolatus, Doryctobracon crawfordi, Utetes anastrephae and Opius hirtus (the first is exotic, and the others are natives to Mexico), parasitoids of Anastrepha fruit flies, are described and compared. The possible implications on interspecific competition among these species are discussed. The most significant adaptations found were: (1) the mouth apparatus, where the large mandibles and fang-shaped maxillary lobes present in D. longicaudata and U. anastrephae larvae were absent in O. hirtus, D. areolatus and D. crawfordi larvae, and (2) the degree of mobility for exploration and escape, such as the lateral and caudal appendages that were only present in D. longicaudata (ventrolateral appendages in the base of the head capsule), U. anastrephae (caudal lobe with two appendages) and D. areolatus (caudal lobe with a round apex with a globular shape). The first instar larvae of the species D. longicaudata show morphological adaptations that apparently confer competitive advantages against the larvae of D. areolatus, D. crawfordi and O. hirtus. However, the first instar larvae of U. anastrephae show larger mandibles, an adaptation that could enable this species to resist competition from D. longicaudata.

Long-term attraction and toxic effects of tephritid insecticide-bait mixtures by applying Torricelli's barometer principle in a trapping device.

BACKGROUND: The field activity of the mixtures of liquid baits and insecticides used in the control of tephritid pests is normally short, both when they are sprayed or when used in trapping or in attract-and-kill devices. A new lure-and-kill device based on Torricelli's barometer principle was tested as a long-lasting dispenser for two liquid hydrolysed protein baits mixed with insecticide, GF-120 and Captor 300 + malathion, against Anastrepha ludens (Loew) flies of laboratory origin. The dispensers were kept under field conditions for 42 days. Laboratory bioassays for insecticide properties and field cage studies for attraction capacity were carried out on a weekly basis after 22 and 42 days of weathering respectively. RESULTS: Our results demonstrated that both mixtures of insecticides and phagostimulant baits killed up to 80% of the tested flies when they were 42 days old. The attraction capacity of both weathering-exposed mixtures was even higher than fresh insecticidal-bait mixtures after the same period. CONCLUSION: The device is efficient when used with the liquid baits currently employed in the control of tephritid flies. It also offers a high potential for combining visual stimuli, such as shape and colour, and for improving trapping and bait station designs. Incorporating this new device in trapping and attract-and-kill methods could help to reduce the frequency of servicing of the traps and bait stations and lower their costs. © 2015 Society of Chemical Industry.