Comparative Study of the Morphology of the Ovipositor ofPlatygaster diplosisae(Hymenoptera: Platygasteridae) andAprostocetus procerae(Hymenoptera: Eulophidae) Two Parasitoids Associated with the African Rice Gall Midge,Orseolia oryzivora(Diptera: Cecidomyiidae)

Abstract

We studied the morphology of the ovipositor ofPlatygaster diplosisae(Hymenoptera: Platygasteridae) andAprostocetus procerae(=Tetrastichus pachydiplosisae) (Hymenoptera: Eulophidae), two parasitoids associated with the African rice gall midge (AFRGM), andOrseolia oryzivora(Diptera: Cecidomyiidae). Scanning electron microscope techniques were used for this study. The ovipositor ofP. diplosisaewas short (40 μm), and most of the sensillae found on it were mechanoreceptors and located on the distal portion of the 3rd valvulae. These sensillae may be involved in selection of an egg or larval host. The shortness of this ovipositor may be an adaptation to a host whose egg envelope thickness is not more than 0.7 μm. The ovipositor ofA. proceraewas 30 times (1.2 mm) the length of theP. diplosisaeovipositor. It was not only well equipped with mechanoreceptive sensillae, but these sensillae were very diverse and distributed along the length of the valvulae. The 10 denticulations of the lancet of this ovipositor allow this parasitoid to exploit hosts that are not otherwise readily accesible. These two parasitoids share the same resource by infesting different life stages of the host. The ovipositor of each species of parasitoid enhanced resource sharing, due to its length and its sensillae type and distribution.

Morphology, ultrastructure, and probable functions of the sense organs on the ovipositor stylets of the hymenoptran parasitoid, Venturia canescens (Gravenhorst)

“…These sensilla also occurred on the ovipositor of Trybliographa rapae (Brown and Anderson,1998) and Leptoplina heterotoma (van Lenteren et al,2007); however, these were found in large numbers in these latter two species but were few in number in this study. Nacro and Nénon (2009) observed these sensilla on the ovipositor of Aprostocetus procerae (Risbec) on which they were also few number; the authors assigned no function to them. However, these sensilla do occur on the antennae of a large number of hymenopteran parasitoids (Miller,1972; Norton and Vinson,1974a, b; Lane et al,1988; Navasero and Elzen,1991; Butterfield and Anderson,1994; Skilbeck and Anderson,1996; Meyhofer et al,1997; Ochieng et al,2000; Bleeker et al,2004; Roux et al,2005; Bourdais et al,2006; Dweck and Gadallah,2008).…”

“…Chiappini and Solinas (2002) observed these sensilla on the ovipositor of Anagrus breviphragma (Soyka), and Dweck et al (2008) reported them on the ovipositor of Hebrobracom hebitor (Say) to which they assigned a tactile function. Nacro and Nénon (2009) described them on the ovipositor of Aprostocetus procerae (Risbec) and Platygaster diplosisae (Risbec). Campaniform sensilla display a lot of variation in form and structure and can be detected on various parts of an insect including the antennae (Dietz and Humphreys,1971; Miller,1972; Mclver,1975; Alm and Kurczewski,1982; Lane et al,1988; Navasero and Elzen,1991; Skilbeck and Anderson,1996; Dweck and Gadallah,2008).…”

“…Sense organs on the hymenopteran ovipositor stylets and sheath have been described by King and Fordy (1970), Ganesalingam (1972), van Lenteren (1972), Hawke et al (1973), Greany et al (1977), Le Ralec and Wagnberg (1990), Nénon et al (1997), Brown and Anderson (1998), Shah (1998), Cônsoli et al (1999), Quicke et al (1999), van Lenteren et al (2007), Dweck et al (2008), Boring and Sharkey (2009), Nacro and Nénon (2009), and Obonyo et al (2011) using electron microscopy.…”

“…Parasitoids are able to discriminate parasitized hosts from unparasitized ones (Arthur,1971; Bakker et al,1967; Brown and Anderson,1998; Chiappini and Solinas,2002; Cônsoli et al,1999; Dweck et al,2008; Fisher and Ganesalingam,1970; Ganesalingam,1969, 1974; Guillot et al,1974; Holler et al,1993; Nacro and Nénon,2009; Nelson and Roitberg,1993; Price,1970, 1972; Quicke et al,1999; van Lentern,1972; van Lenteren et al,2007; Vinson and Guillot,1972; Wylie,1970, 1971). So, there is a need to identify the organs on the body of these parasitoids that are capable of host‐discrimination.…”

Electrophysiological activity of the Sirex noctilio ovipositor: You know the drill?

“…Contact chemoreceptors are present on the ovipositors of a variety of insect species (Rice, 1976;Hood Henderson, 1982;Waladde, 1983;Crnjar et al, 1989;Maher and Thiéry, 2004;Maher et al, 2006;Faucheux, 2012), including Hymenoptera (Nacro and Nénon, 2009). The presence of these sensilla is likely to be associated with oviposition in fresh plants: indeed, the uniporous sensilla are known to respond to chemicals such as salts, water, and amino acids (Rice, 1976;Chadha and Roome, 1980).…”