A needle in a haystack: Mesozoic origin of parasitism in Strepsiptera revealed by first definite Cretaceous primary larva (Insecta).

Hans Pohl,Jan Batelka,Patrick Müller,Margarita I Yavorskaya,Rolf G Beutel,Jakub Prokop

doi:10.7717/peerj.5943

Abstract

Twisted winged insects (Strepsiptera) are a highly specialized small order of parasitic insects. Whether parasitism developed at an early or late stage in the evolution of the group was unknown. Here we record and describe the first definite Mesozoic strepsipteran primary larva embedded in Burmese amber (∼99 million years ago). This extends the origin of parasitism back by at least ∼50 million years, and reveals that this specialized life style has evolved in the Mesozoic or even earlier in the group. The extremely small first instar displays all diagnostic characters of strepsipteran immatures of this stage and is nearly identical with those of Mengenillidae, one of the most “ancestral” extant strepsipteran taxa. This demonstrates a remarkable evolutionary stasis over 100 million years. The new finding strongly weakens the case of small larvae embedded in Cretaceous amber interpreted as strepsipteran immatures. They differ in many structural features from extant strepsipteran primary larvae and are very likely parasitic beetle larvae.

Highlights

Strepsiptera is a highly specialized small order of holometabolous insects (Pohl & Beutel, 2008; Pohl & Beutel, 2013)
The oldest recorded fossils are known from Cretaceous Burmese amber (Grimaldi, Kathirithamby & Schawaroch, 2005; Pohl & Beutel, 2016; Engel et al, 2016), indicating a minimum age of ca. 100 mya
In the present study we describe a minute larva from a piece of Burmese amber, with a habitus and a set of observable features unambiguously confirming a placement in Strepsiptera

Summary

Introduction

Strepsiptera is a highly specialized small order of holometabolous insects (Pohl & Beutel, 2008; Pohl & Beutel, 2013). The oldest recorded fossils are known from Cretaceous Burmese amber (Grimaldi, Kathirithamby & Schawaroch, 2005; Pohl & Beutel, 2016; Engel et al, 2016), indicating a minimum age of ca. 120 mya was estimated based on molecular data (McMahon, Hayward & Kathirithamby, 2011). The confirmed sister group relationship with Coleoptera (Misof et al, 2014) implies that the group originated already in the early Permian or late Carboniferous (McKenna et al, 2015; Toussaint et al, 2017). How to cite this article Pohl H, Batelka J, Prokop J, Müller P, Yavorskaya MI, Beutel RG. A needle in a haystack: Mesozoic origin of parasitism in Strepsiptera revealed by first definite Cretaceous primary larva (Insecta).

Methods

Results

Discussion

Conclusion