Nectary use for gaining access to an ant host by the parasitoid Orasema simulatrix (Hymenoptera, Eucharitidae)

Abstract

Eucharitidae is the only family of insects known to specialize as parasitoids of ant brood. Eggs are laid away from the host onto or in plant tissue, and the minute first-instars (planidia) are responsible for gaining access to the host through some form of phoretic attachment to the host ant or possibly through an intermediate host such as thrips. Orasema simulatrix (Eucharitidae: Oraseminae) are shown to deposit their eggs into incisions made on leaves of Chilopsis linearis (Bignoniaceae) in association with extrafloral nectaries (EFN). Nectary condition varies from fluid-filled on the newest leaves, to wet or dry nectaries on older leaves. Filled nectaries were about one third as common as dry nectaries, but were three times as likely to have recent oviposition. Larger numbers of undeveloped eggs, or eggs with mature planidia inside, were associated with filled and wet EFN. For emerged planidia, the distribution was shifted from a concentration at filled nectaries to an even greater concentration at wet nectaries. More planidia were found in EFN (9.50 ±2.85) than outside EFN (1.00 ± 0.60). Planidia were tested for their attachment to adult and larval ants and to adult and immature thrips (potential intermediate host), but the results do not support simple attachment as a viable means for transfer and successful parasitism. Pheidole desertorum was identified as the host ant, and at night is the dominant ant in the tree canopy of C. linearis. Feeding at the EFN by the host ant, and the direct association with planidia near to or in the EFN, is interpreted as a novel means of accessing the host brood.

The life history of Pseudometagea schwarzii, with a discussion of the evolution of endoparasitism and koinobiosis in Eucharitidae and Perilampidae (Chalcidoidea)

“…Literature records for internal or external parasitism by planidia on their larval host are known for 27 species of Perilampidae (Chrysolampinae and Perilampinae) and Eucharitidae (Wheeler 1907, Smith 1912, Brues 1919, Ford 1922, Clausen 1923, 1928, 1940a, Wheeler and Wheeler 1937, Clancy 1946, Ayre 1962, Tripp 1962, Askew 1980, Laing and Heraty 1981, Heraty and Darling 1984, Darling and Miller 1991, Darling 1992, 1999, Heraty et al 1993, Heraty 1994, 2000, 2002, Darling and Roberts 1999, Pérez-Lachaud et al 2006, Carey et al 2012, Lachaud and Pérez-Lachaud 2012, Torréns 2013) (cf. Table 1).…”

A new species of Eucharissa Westwood (Eucharitidae) from South Africa, with an evaluation of the importance of pupae for assessing relationships in these ant parasitoids

“…Pupae have been documented in detail for Gollumiellinae: Gollumiella Hedqvist (Heraty et al 2004); Oraseminae: Australosema Heraty & Burks (as Orasema, Heraty 1994), Hayatosema Heraty & Burks (as Orasema, Das 1963), Ibitya Heraty & Burks (Burks et al 2017), Ivieosema Heraty & Burks (as Orasema, Reichensperger 1913), Orasema Cameron (11 spp. ;Baker and Heraty in press;Burks et al 2018;Carey et al 2012;Chien and Heraty 2018;Heraty 1994;Heraty et al 1993;Herreid and Heraty 2017;van Pelt 1950;Wheel-er and Wheeler 1937;Wheeler 1907), Timioderus Waterston (Heraty, 2000), and Zuparka Heraty & Burks (as Orasema, Heraty 2000); and Eucharitinae: Athairocharis Heraty (Heraty, 2002), Austeucharis Bouček (Brues, 1919), Chalcura Kirby (Clausen, 1940), Dilocantha Shipp (Torréns, 2013), Eucharis (Clausen, 1940, morphology characteristics (or lack thereof ) inferred by his reference to attributes of the other genera), Galearia Brullé (Torréns, 2013), Lophyrocera Cameron (Torréns et al 2008), Kapala Cameron (2 spp. ;Clausen 1940;Pérez-Lachaud et al 2006;Rocha et al 2020), Mateucharis Heraty (Heraty, 2002), Neolosbanus Heraty (2 spp., Heraty 1994), Pseudochalcura Ashmead (Wheeler 1907), Pseudometagea Ashmead (Heraty and Murray 2013), Schizaspidia Westwood (3 spp.…”