Parasitoid-induced mortality of Araneus omnicolor (Araneae, Araneidae) by Hymenoepimecis sp. (Hymenoptera, Ichneumonidae) in southeastern Brazil

Abstract

All species included in the Polysphincta genus-group develop as ectophagous parasitoids of active spiders, killing their hosts prior to pupation. However, little information regarding natural history and ovipositing behavior of most species are available. In this study we inspected 85 webs of Araneus omnicolor to evaluate the frequency of parasitism and host size preferences of the wasp Hymenoepimecis sp. We also described the web characteristics of normal and parasitized spiders and the wasp ovipositing behavior. About 41% of the adult females of A. omnicolor inspected were parasitized. The highest incidence of parasitism was observed among relatively small females while no egg or larva was found in large individuals. Araneus omnicolor builds a strong web composed of an orb and barrier threads, where the spider rests within a curled leaf. The parasitoid larva builds its cocoon within this refuge, and modified cocoon webs were not observed. The ovipositing behavior of Hymenoepimecis sp. was very similar to that of Hymenoepimecis argyraphaga parasitizing Leucauge argyra, including the position of the sting, the killing of a previously attached larva, and the expelling of the egg from the base of the ovipositor.

An alternative host of Hymenoepimecis japi (Hymenoptera, Ichneumonidae) on a novel family (Araneae, Araneidae), with notes on behavioral manipulations

“…The cocoon web constructed by M. biggiba resembles those induced by other Hymenoepimecis (Gonzaga et al 2010) and Acrotaphus wasp parasitism (Gonzaga and Sobczak 2011) by the presence of a dense and irregular tangle of non-sticky threads with several points of contact with the surrounding vegetation. The absence of the normal dome shaped portion and the high number of condensed support threads consists of a physical barrier that probably protects the cocoon and enhances the stability of the web.…”

“…Several studies have described behavioral manipulations of spiders by the clade of koinobiont ectoparasitoid wasps of the Polysphincta genus-group (hereafter polysphinctine wasps) (Ichneumonidae: Pimplinae) (Gonzaga and Sobczak 2007, Matsumoto 2009, Korenko and Pekár 2011, Eberhard 2013, Sobczak et al 2014, Kloss et al 2016. Eberhard (2010) proposed that psychotropic substances released by wasp larva are the driving force behind behavioral manipulations of host spiders, but no additional studies have confirmed this hypothesis.…”

“…These parasitoid wasps are known to attack spiders of five genera, namely: Nephila (Araneidae; Finke et al 1990, Gauld 1991, 2000, Gonzaga et al 2010, Leucauge (Tetragnathidae; Gauld 1991, Eberhard 2000a, 2001, Eberhard 2013, Pádua et al 2016, Cyrtophora (Araneidae; Gauld 2000), Araneus (Araneidae; Gonzaga and Sobczak 2007, Sobczak et al 2011, 2014 and Manogea (Araneidae; ). Until now, 12 of the 20 validspecies of Hymenoepimecis are confirmed to be capable of parasitizing subadult and adult orb-weaving spiders (summarized in Pádua et al 2016) and inducing their hosts to construct a variety of cocoon web designs, from simple two-dimensional to complex three-dimensional tangles of non-sticky threads.…”

“…On current understanding, Hymenoepimecis -spider interactions are frequently species-specific, with an exception in H. veranii Loffredo & Penteado-Dias, 2009 that parasitizes two congeneric and sympatric araneid spiders Araneus omnicolor (Keyserling, 1893) and A. orgaos Levi, 1991(Gonzaga and Sobczak 2007, Sobczak et al 2014. Our study species, Hymenoepimecis japi Loffredo & Penteado-Dias, 2009 (male described by Sobczak 2012), is known to parasitize the orb-weaver spider Leucauge roseosignata Mello-Leitão, 1943 (Tetragnathidae) ).…”

Parasitism on Araneus venatrix (Koch, 1838) (Araneae: Araneidae) by Hymenoepimecis silvanae Loffredo and Penteado-Dias, 2009 (Ichneumonidae, Pimplinae) with description of male of the wasp

“…The species are characterised by the presence of a pocket-like structure on the pronotum, mesopleuron with carina epicnemial vestigial or absent, absence of the vein 3 rs-m in fore wing (Gauld, 1991), colour yellowish brown and large ocelli (Gauld and Dubois, 2006). All known species are koinobiont parasitoids of adult spiders of the family Nephilidae, Tetragnathidae and Araneidae (Fincke et al, 1990;Eberhard, 2000;Gauld, 2000;Gonzaga and Sobczak, 2007;Gonzaga et al, 2010). Despite this wide geographical distribution, little is known on host identities.…”