Development of Thripastichus gentilei (Hymenoptera: Eulophidae) in the Thrips Gynaikothrips uzeli (Thysanoptera: Phlaeothripidae)

Gynaikothrips uzeli (Zimmermann) (Thysanoptera: Phlaeothripidae) adults induce permanent leaf folds on Ficus benjamina L. (Moraceae), inside which they feed and reproduce. Range expansion of G. uzeli in North America was accompanied by Thripastichus gentilei (del Guercio) (Hymenoptera: Eulophidae). The objectives of this study were to determine the life stage(s) of G. uzeli parasitized by T. gentilei, the emergence period of T. gentilei from parasitized thrips, and the adult longevity of T. gentilei. We also determined the development time for both parasitoid and host at a constant temperature. Leaf folds representing only 1 life stage of G. uzeli were challenged with T. gentilei adults to determine life stage susceptibility. In a growth chamber at 30 °C, we recorded the development time for the thrips host and observed the emergence period of T. gentilei from thrips. Wasps were provisioned with liquid diets to determine longevity. Development of G. uzeli required 10.3 d at 30 °C with successful parasitism of only 1st and 2nd instars of the thrips. Wasps emerged from thrips about 20 d after their exposure to females and could survive in the laboratory for about 3 d longer when provisioned with sugar solution relative to water only or starved wasps. We concluded that T. gentilei, released for control of Gynaikothrips ficorum (Marchal) (Thysanoptera: Phlaeothripidae) is now also using G. uzeli as a host. This larval parasitoid takes about twice as long as G. uzeli to develop, yet adults can survive up to 16 d when a carbohydrate source is present. Thripastichus gentilei should complement the activity of other natural enemies attacking Gynaikothrips species on Ficus. However, the development rate of G. uzeli and its potential interactions with Montandoniola confusa Streito & Matocq (Hemiptera: Anthocoridae) may limit the ability of T. gentilei to establish on plants wherever this anthocorid is present.