Optimizing survival of Leptocybe invasa (Hymenoptera: Eulophidae) parasitoids: effects of nutrition and temperature

The distribution and economic impact of the invasive gall wasp Leptocybe invasa Fisher & La Salle, 2004 (Hymenoptera: Eulophidae), a major pest of eucalyptus, are global. Quadrastichus mendeli Kim & La Salle, 2008 and Selitrichodes neseri Kelly & La Salle, 2012 (Hymenoptera: Eulophidae) are effective biological control agents of this pest, but their use depends on optimizing laboratory rearing protocols. This study assessed the longevity and survival of Q. mendeli females fed different diets and maintained at temperatures from 18 to 30 °C, and of Q. mendeli females and S. neseri males and females fed different diets at 24 °C. The experiment was conducted in a completely randomized factorial design. Longevity data were analyzed using generalized linear models, and survival was analyzed using Kaplan-Meier survival curves. Longevity and survival varied according to diet and temperature for Q. mendeli females and according to diet at 24 °C for S. neseri males and females. Quadrastichus mendeli females reaching a maximum longevity of 104.7 d with honey diets at moderate temperature. At 24 °C, S. neseri females and males reached maximum longevities of 23.25 d, and 17.00 d, respectively, with honey diets. Longevity declining under starvation or the pollen-only diet. Female longevity exceeded that of males, and Q. mendeli lived longer than S. neseri. Parasitoid longevity and survival were highest with honey diets at moderate temperatures, providing practical conditions for laboratory maintenance, mass rearing, and release of these parasitoids in biological control programs against L. invasa.