Inter-specific competition and competition-free space in the tephritid parasitoids Utetes anastrephae and Doryctobracon areolatus (Hymenoptera: Braconidae: Opiinae)

Authors: ALUJA, MARTIN - Institute De Ecologia - Mexico; OVRUSKI, SERGIO - Experimental Plant For Industrial Microbiological Processes(PROIMI); Sivinski, John; CORDOVA-GARCIA, GUADALUPE - Institute De Ecologia - Mexico; SCHLISERMAN, PABLO - Experimental Plant For Industrial Microbiological Processes(PROIMI); NUNEZ-CAMPERO, SEGUNDO - Experimental Plant For Industrial Microbiological Processes(PROIMI); ORDANO, MARIANO - Consejo Nacional De Investigaciones Científicas Y Técnicas(CONICET)

Submitted to: Ecological Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/23/2013
Publication Date: 8/14/2013
Citation: Aluja, M., Ovruski, S.M., Sivinski, J.M., Cordova-Garcia, G., Schliserman, P., Nunez-Campero, S.R., Ordano, M. 2013. Inter-specific competition and competition-free space in the tephritid parasitoids Utetes anastrephae and Doryctobracon areolatus (Hymenoptera: Braconidae: Opiinae). Ecological Entomology. 38:485-493.

Interpretive Summary: Several species of parasitoids often attack the same host and their coexistence depends on their being able to avoid competition with one another. Scientists at the USDA-Agriculture Research Service, Center for Medical, Agricultural and Veterinary Entomology in Gainesville, Florida, with collaborators from The Instituto de Ecologia, Veracruz, Mexico examined how two common natural enemies of pest fruit flies are able to share habitats and hosts. Hatchlings of one species always eliminated the other when both were present in the same fruit fly maggot. However, the weaker species has a longer ovipositor as an adult and is able to attack hosts in larger fruit. Thus it can find shelter in a “competitor-free-space”. These differences seem to explain the distribution of these wasps in the USA where they were introduced for the biological control of the Caribbean fruit fly and the results of this study are being used to guide their introduction into the Dominican Republic for the control of the West Indian fruit fly.

Technical Abstract: The outcomes of multiparasitism (host occupation by parasitiods of more than one species) are often predictable, one species typically outcompeting another. Utetes anastrephae and Doryctobracon areolatus are common, native, neotropical braconid parasitoids of tephritid fruit flies that are sympatric and often found attacking the same host. Utetes anastrephae had a competitive advantage over Doryctobracon areolatus when they occurred in multiparasitized hosts, and this advantage occurred regardless of the order in which the two parasitoids attacked. Although we could not identify the precise mechanisms used for elimination of competitors, a possible cause is suggested by the formidable mandibles of the first-instar U. anastrephae. The comparatively shorter body and head size and the relatively poorly developed mandibles of the first-instar larva of D. areolatus, may place it at a disadvantage in combats with a first-instar U. anastrephae. However, Doryctobracon areolatus survival increased significantly if eggs had been deposited 24 h prior to exposure to U. anastrephae. Older D. areolatus larvae might be more competitive after a period of development. In addition, U. anastrephae females were less likely to oviposit into hosts previously attacked by D. areolatus than vice versa. The survival of the less intrinsically competitive D. areolatus may be due its longer ovipositor that permits it to attack larvae in larger fruit than U. anastrephae. This would increase its potential host range and provide “competitor-free space”.