Extreme convergence in egg-laying strategy across insect orders

Abstract

The eggs of stick and leaf insects (Phasmatodea) bear strong resemblance to plant seeds and are commonly dispersed by females dropping them to the litter. Here we report a novel egg-deposition mode for Phasmatodea performed by an undescribed Vietnamese species of the enigmatic subfamily Korinninae that produces a complex egg case (ootheca), containing numerous eggs in a highly ordered arrangement. This novel egg-deposition mode is most reminiscent of egg cases produced by members of unrelated insect orders, e.g. by praying mantises (Mantodea) and tortoise beetles (Coleoptera: Cassidinae). Ootheca production constitutes a striking convergence and major transition in reproductive strategy among stick insects, viz. a shift from dispersal of individual eggs to elaborate egg concentration. Adaptive advantages of ootheca formation on arboreal substrate are likely related to protection against parasitoids and desiccation and to allocation of specific host plants. Our phylogenetic analysis of nuclear (28S, H3) and mitochondrial (COI, COII) genes recovered Korinninae as a subordinate taxon among the species-rich Necrosciinae with Asceles as sister taxon, thus suggesting that placement of single eggs on leaves by host plant specialists might be the evolutionary precursor of ootheca formation within stick insects.

Subdivision of the neotropical Prisopodinae Brunner von Wattenwyl, 1893 based on features of tarsal attachment pads (Insecta, Phasmatodea)

“…Günther (1953) placed the whole group as a subordinate taxon of the Pseudophasmatinae Rehn, 1904. This view is supported as well by Bradley and Galil (1977) as by more recent phylogenetic analyses (Bradler 2009, Goldberg et al 2015). Zompro (2004) recovered the Prisopodinae and arranged it to the two remaining tribes Prisopodini Brunner von Wattenwyl 1893, which includes Damasippus Stål, 1875, Dinelytron Gray, 1835 and Prisopus Peletier de Saint Fargeau & Serville, 1828, and Paraprisopodini Zompro, 2004 with Melophasma Redtenbacher, 1906 and Paraprisopus Redtenbacher, 1906.…”

Multiple Identified Neurons and Peripheral Nerves Innervating the Prothoracic Defense Glands in Stick Insects Reveal Evolutionary Conserved and Novel Elements of a Chemical Defense System

“…In addition, the intersegmental nerve complex innervates the glands by the posterior subesophageal nerve and the anterior prothoracic nerve in most species studied (Stolz et al, 2015). Between these distantly related groups (Goldberg et al, 2015), the peripheral nerve pattern is conserved. Notably, in Peruphasma schultei only the anterior subesophageal nerve innervates the defense glands, but not the intersegmental nerve complex (Stolz et al, 2015).…”

“…SOG (Stolz et al, 2015). Anisomorpha species are very closely related to P. schultei (Goldberg et al, 2015), but the defense gland innervation is not specialized exclusively to the N. ant. SOG.…”

“…The aim of this study is (1) to document the innervation pattern of the defense gland for a species from a genus which has a strong spraying defense behavior from prominent defense glands (Eisner, 1965), (2) to identify the particular neurons which innervate the defense gland muscles in nerves which also target adjacent muscles (Stolz et al, 2015), and (3) to compare the innervation in A. paromalus to the closely related P. schultei (both Pseudophasmatinae; Goldberg et al, 2015) for the functional specialization on the N. ant. SOG innervation.…”

Description of the female, egg and first instar nymph of the stick insect Paraphasma paulense (Phasmatodea: Pseudophasmatidae) from Southeast Brazil

“…Recently, only a few studies have addressed Brazilian stick insects, such as: three broad taxonomic revisions that included some Brazilian taxa (Zompro 2001, 2004, Hennemann et al 2016; the redescription of Tithonophasma tithonus (Gray, 1835) (Lima et al 2013); and the descriptions of one new species in the genus Cladomorphus Gray, 1835 (Kumagai and Fonseca 2009), and another in Agrostia Redtenbacher, 1906(Heleodoro et al 2017. Furthermore, few Brazilian species have the egg described in spite of the importance of egg morphology and egg-laying mechanism in Phasmatodea taxonomy and phylogenetics (Sellick 1997, Clark Sellick 1998, Zompro 2004, Goldberg et al 2015.…”