Biodiversity of Strepsiptera

Strepsiptera, often referred to as “twisted‐ wing” parasitoids, are bizarre insects with unusual morphology (Kinzelbach 1971a, 1971b, 1978; Kathirithamby 1989a, 1991a, 2009). They are a small order of holometabolous insects, comprising 15 families, five of which are extinct (Table 22.1). All species are obligate entomophagous endoparasitoids for three of their larval stages. In the suborder Stylopidia, however, endoparasitism in the male continues through the pupal stage, and the pedomorphic female remains permanently embedded in the host up to maturity, and even up to the production of the motile first‐instar planidia. Strepsiptera also display unusual genetic characteristics. They possess one of  the smallest insect genomes (108 Mbp) (Johnston et  al. 2004), yet have one of the larger 18S ribosomal DNA sequences associated with a number of unique and unusually long insertions (Gillespie et  al. 2005, Matsumoto et al. 2011). There are also two transfer RNA translocations that disrupt an otherwise ancestral insect mitochondrial genome (McMahon et  al. 2009). Both the mitochondrial DNA and the nuclear ribosomal DNA underwent a significant burst of molecular evolution in the early history of Strepsiptera (McMahon et al. 2011).