Antennal sensilla of Apanteles cypris Nixon (Hymenoptera: Braconidae), a larval endoparasitoid of Cnaphalocrocis medinalis Guenée (Lepidoptera: Pyralidae)

Abstract

Apanteles cypris is an endoparasitoid of rice pest Cnaphalocrocis medinalis. To better understand its host location mechanism, we examined the external morphology of antennal sensilla of A. cypris via scanning electron microscopy. The antennae of male and female A. cypris were filiform in shape, which consist of scape, pedicel, and flagellum with 18 antennomeres. Eleven types of sensilla were recorded in both sexes, including two types of chaetica sensilla, trichodea sensilla without pore, basiconica sensilla I with a tip pore, basiconica sensilla II with wall pores, basiconica sensilla III with a mastoid at the tip, coeloconica sensilla with apparent fingerlike projections, campaniform sensilla with a sprout tip pore, clavatea sensilla, smell pore, and placodea sensilla (PLA) with the multiporous cuticular structure. We also compared the morphology, number, and distribution of the sensory receptors between the two sexes. The length and width of the antennae on the males were significantly greater than that of females. In addition, males of A. cypris showed a larger number and a higher density of PLA compared to females. The morphology and structure of these sensilla were compared to that found in other braconid wasps, and their possible functions in host location were discussed. These observations could facilitate future studies on the biology of olfaction in A. cypris.

Diverse Filters to Sense: Great Variability of Antennal Morphology and Sensillar Equipment in Gall-Wasps (Hymenoptera: Cynipidae)

“…In Ichneumonoidea, SB was found in some Braconidae, though with morphology very different from that we found in Cynipoidea, and different also from that found in other Hymenoptera, i.e. with a more trichoid, skinnier shape [23], [27], [74], [98]. Due to this elongate shape, some studies named these SB as “fluted basiconic sensilla” [18], while Bleeker et al [24] and Barbarossa et al [99] directly consider them as sensilla trichoidea.…”

Peer Review #2 of "Between extreme simplification and ideal optimization: antennal sensilla morphology of miniaturized Megaphragma wasps (Hymenoptera: Trichogrammatidae) (v0.1)"

“…Sensilla chaetica, aporous (ChS-AP) ChS-AP are common in parasitoid wasps and have been described in almost every study on antennal sensilla. They often are the most abundant type on the antenna (Onagbola & Fadamiro, 2008;Das et al, 2011;Xi et al, 2011;Zhou et al, 2011Zhou et al, , 2013bYang et al, 2016). Their aporous walls, elongated shape, and presence of the basal socket suggest a mechanosensory function, which agrees with TEM data (Chiappini, Solinas & Solinas, 2001).…”

“…When the wasp moves its antenna, these sensilla touch the surface of antennal socket, and their initial orientation is distorted (Schmidt & Smith, 1986). Thus, these sensilla are considered proprioceptors (Onagbola & Fadamiro, 2008;Dweck, 2009;Xi et al, 2010, Zhou et al, 2011Wang, 2013;Namikawa & Amornsak, 2016;Yang et al, 2016). These sensilla are sometimes termed the "Böhm bristles" after Böhm, who described them in Lepidoptera (Böhm, 1911).…”

“…Within-species variations of sensillum sizes, numbers of sensilla, and their morphology is often described, and were thoroughly studied in Trichogramma evanescens Westwood, 1833 (Hymenoptera: Trichogrammatidae) (van der Woude & Smid, 2016). Most of the studies treat Braconidae (Xi et al, 2010;Zhou et al, 2011) and Chalcidoidea, with special emphasis on Trichogrammatidae, Scelionidae and Platygastridae (Cave & Gaylor, 1987;Olson & Andow, 1993;Amornsak, Cribb & Gordh, 1998;Isidoro, Romani & Bin, 2001;Zhang et al, 2012). Some studies covered the biology and behavior associated with the antennal sensilla in parasitoid wasps, making it possible to predict the functions of some types of sensilla (Norton & Vinson, 1974;Schmidt & Smith, 1986).…”

Antennal sensilla of female Encarsia guadeloupae Viggiani (Hymenoptera: Aphelinidae), a nymphal parasitoid of the spiraling whitefly Aleurodicus dispersus (Hemiptera: Aleyrodidae)

“…Uniporous sensilla trichodea (ST-UP) is akin with "basiconica sensilla I" found in Microplitis croceipes (Ochieng et al, 2000) and Apanteles cypris (Zhou et al, 2011). ST-UP have been described as fluted basiconic sensilla in Cardiochiles nigriceps (Norton and Vinson, 1974b), s. basiconica A in Microplitis croceipes (Navasaro and Elzen, 1991), or curved trichoid formations with an apical pore in Opius concolor (Barbarossa et al, 1998), uniporous sensillum trichoideum in Trichogramma galloi and Trichogramma pretiosum (Cônsoli et al, 1999), sensilla trichodea TP in Cotesia glomerata (Bleeker et al, 2004), Basiconica sensilla I in A. cypris (Zhou et al, 2011).…”