Effects of exposure time and ratio of irradiated larvae from three medfly strains on progeny yield in Diachasmimorpha longicaudata (Hymenoptera: Braconidae) mass rearing

CARTA GADEA, SILVIA LORENA; SUÁREZ, LORENA; BUONOCORE BIANCHERI, MARÍA JOSEFINA; MURÚA, FERNANDO; MOLINA, DIEGO; LARIA, OSVALDO; OVRUSKI, SERGIO M.

BIOCONTROL SCIENCE AND TECHNOLOGY

TAYLOR & FRANCIS LTD

Año: 2020 vol. 30 p. 592 - 601

0958-3157

An augmentative biological control strategy against Ceratitis capitata(= medfly) in fruit-producing irrigated-valleys of San Juan, centralwesternArgentina, has been recently implemented by the San JuanFruit Fly Control and Eradication Program. The Asian-nativeparasitoid Diachasmimorpha longicaudata is currently reared at theSan Juan Medfly and Parasitoids Mass Rearing Facility for thispurpose. In this regard, the objective of this study was to evaluateadult emergence and offspring sex ratio to improve parasitoidproduction. Three medfly strains at different host larvae densitiesand exposure times to female parasitoids were assessed. Prevalenceof superparasitism was also considered. Three parasitoid populationlines were used in the trials: one reared on medfly larvae of theVienna-8 temperature-sensitive lethal (tsl) genetic sexing strainwithout inversion, and the other two on larvae of biparental medflystrains native to San Juan (central-western Argentina) and Tucumán(northwestern Argentina). Gamma-irradiated 6 d-old larvae (earlythird-instars) of each medfly strain were exposed to parasitoids for30, 60, 90, and 120 min at 3:1, 6:1, and 9:1 host/parasitoid ratios.The Vienna-8 C. capitata strain was as efficient in producingparasitoids as both biparental native strains. Medfly larvae exposedto 10 female parasitoids for a relatively long time (1.30 hrs) at ahigh ratio (6?9:1) of host to parasitoid were enough to achieve thehighest mean adult emergence (50?60%) and a female-biasedoffspring sex ratio. Superparasitism positively influenced femaleparasitoid production. These findings may be used to develop amore cost-effective mass rearing method for D. longicaudata.