BIOLOGICALLY-BASED TECHNOLOGIES FOR MANAGEMENT OF CROP INSECT PESTS IN LOCAL AND AREAWIDE PROGRAMS
Location: Insect Behavior and Biocontrol Research Unit
Title: Longevity of multiple species of tephritid (Diptera) fruit fly parasitoids (Hymenoptera: Braconidae: Opiinae) provided exotic and sympatric-fruit based diets
Submitted to: Journal of Insect Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 29, 2011
Publication Date: November 15, 2011
Citation: Stuhl, C.J., Jurado, L.C., Sivinski, J.M., Teal, P.E., Lapointe, S.L., Paranhos, B., Aluja, M. 2011. Longevity of multiple species of tephritid (Diptera) fruit fly parasitoids (Hymenoptera: Braconidae: Opiinae) provided exotic and sympatric-fruit based diets. Journal of Insect Physiology. 57:1463-1470.
Interpretive Summary: Fruit flies infest hundreds of fruits and vegetables and are responsible for trade restrictions wherever they occur. Mass-reared and released parasitoid wasps are a promising technology for their control but little is known of their adult diets and whether food sources might contain chemicals that could be used as an attractant to monitor their survival. Scientists at the USDA-ARS Center for Medical, Agricultural and Veterinary Entomology in Gainesville, Florida provided four species of parasitoids with either honey, orange or guava pulp/juice. Orange juice and honey were similarly nutritious but guava was toxic, perhaps because of compounds called furans. Volatiles from oranges were more attractive than those from guava, and orange-chemicals are being examined for attractiveness in flight tunnels.
While adult parasitic Hymenoptera in general feed on floral and extrafloral nectars, hemipteran-honeydews and fluids from punctured hosts, Diachasmimorpha longicaudata (Ashmead), an Old World opiine braconid introduced to tropical/subtropical America for the biological control of Anastrepha spp. (Tephritidae), can survive on fruit juices as they seeps from injured fruit. An ability to exploit fruit juice would allow such a parasitoid to efficiently forage for hosts and food sources simultaneously. Two New World opiines, Doryctobracon areolatus (Szepligeti) and Utetes anastrephae (Viereck), are also prominent Anastrepha parasitoids and are roughly sympatric. All three species were provided with pulp and juice diets derived from a highly domesticated Old World fruit (orange, Citrus sinensis L.) that offered little opportunity for shared evolutionary histories, except perhaps with D. longicaudata. All three were also provided with a less-domesticated New World fruit (guava, Psidium guajava L.) which potentially shared an evolutionary history with D. areolatus and U. anastrephae. Infested guava is a host source for all three species, but only D. longicaudata commonly parasitizes larvae in citrus. Both sexes of D. longicaudata, from USA and Mexican-derived cultures died when provided guava pulp or juice at a rate similar to a water-only control. In the USA, D. areolatus and U. anastrephae, presumably adapted to the nutrient/chemical constituents of guava also died at a rate similar to that of the water-control. Survival of all three species on orange pulp and juice was greater than on water, and longevity often equaled that obtained on a honey and water solution provided as a positive control. In Mexico, D. areolatus and U. anastrephae, as well as the tephritid parasitoids Doryctobracon crawfordi (Viereck) and Opius hirtus (Fisher), died at a significantly higher rates when provided guava in comparison to two concentrations of a honey and water diet. The differences in survival on the two fruits suggested that guava was either: 1) innutritious, 2) toxic or 3) unattractive. Fructose found in guava sustained both male and female D. longicaudata. However, rhamnose and mannose, sugars known to be toxic to other Hymenoptera, were present in guava, but were either unrecorded or occurred at low levels in citrus. While rhamnose was innutritious, and mannose slightly nutritious for D. longicaudata, neither sugar was toxic at levels realistically occurring in fresh fruit. Furoic acid, a potentially toxic compound found in fresh guava, but not in citrus, shortened D. longicaudata longevity at concentrations of 0.5 %. Starved female D. longicaudata and D. areolatus could be found at guava feeding-stations, although when given a choice between fruit both sexes of all species were generally found at citrus stations. Since guava contained nutrient sugar and could be located by and arrest parasitoids, longevity differences between wasps fed on guava and citrus were most likely due to a toxin, perhaps a furan such as furoic acid. Given the differences in fruit-food quality, adult opiine food sources would not be obtainable at all oviposition sites and more additional foraging for food than previously postulated may be required.