Germline transformation of the stalk-eyed fly, Teleopsis dalmanni

We used in vivo excision assays to identify transposon vector systems with the activity required to mediate transgenesis in T. dalmanni. Mariner based vectors showed no detectable excision while both Minos and piggyBac were active in stalk-eyed fly embryos. Germline transformation with an overall efficiency of 4% was achieved using a Minos based vector and the 3xP3-EGFP marker construct. Chromosomal insertion of constructs was confirmed by Southern blot analysis. Both autosomal and X-linked inserts were recovered. A homozygous stock, established from one of the X-linked inserts, has maintained stable expression for eight generations.We have performed stable germline transformation of a stalk-eyed fly, T. dalmanni. This is the first transgenic protocol to be developed in an insect species that exhibits an exaggerated male sexual trait. Transgenesis will enable the development of a range of techniques for analysing gene function in this species and so provide insight into the mechanisms underlying the development of a morphological trait subject to sexual selection. Our X-linked insertion line will permit the sex of live larvae to be determined. This will greatly facilitate the identification of genes which are differentially expressed during eye-stalk development in males and females.In many species, sexual selection, the varying competitive success of individuals for access to mates [1,2], drives the evolution of exaggerated male displays or ornamental traits and female preference for such traits. The diopsid family of stalk-eyed flies exhibits a well documented and experimentally tractable example of an ornamental sexual trait [3-5]. Males and females have eyes laterally displaced from the head capsule on 'eye-stalks' [6] and the exaggeration of eye-stalks can be extreme with males having eyespans up to twice that of their body length [7,8]. Sexual dimorphism for eyespan, with males having much greater eyespan than females, has evolved several times within the Diop