Chemical information from the fungus Amylostereum areolatum and host‐foraging behaviour in the parasitoid Ibalia leucospoides

Abstract

Parasitoids locate hosts using reliable and predictable cues such as smells derived from host plants or from the hosts themselves. For host species that live with mutualistic organisms, such as several wood boring insects, cues derived from the symbionts are likely to be exploited by specific parasitoids. Through a set of bioassays, the behaviour of the parasitoid Ibalia leucospoides Hochenwarth (Hymenoptera: Ibaliidae) is studied in response to the fungus Amylostereum areolatum Boidin (Basidiomycotina: Corticiaceae), a symbiont of its host, the wood wasp Sirex noctilio Fabricius (Hymenoptera: Siricidae). The results show that parasitoids are attracted to the fungus when growing naturally within pine logs, and also when growing on an artificial medium. Fungal volatiles also elicit increased parasitoid activity and may provide information on relative densities of hosts available for parasitization. It is speculated that the the chemical information derived from the host fungal symbiont comprises reliable and detectable host‐locating cues used by parasitoids to search for concealed hosts.

Behavioural responses of bethylid parasitoid species of the coffee Berry borer to chemicals cues from host and non-host dust/frass

“…An alternative explanation is that the preservative components of the diet affected the microorganisms associated with H. hampei, and therefore the dust/frass volatiles. Some studies have shown that the production of volatile infochemicals depends on the presence of microorganisms and not on enzymes arising from the plant or the herbivore (Godfray 1994;Martínez et al 2006;Steiner et al 2007). Whether some of the microorganisms associated with H. hampei are involved in the production of volatile kairomone remains to be investigated.…”

Food and Host Searching Decisions Made by Ibalia leucospoides (Hymenoptera: Ibaliidae), a Parasitoid of Sirex noctilio (Hymenoptera:Siricidae)

“…Females of I. leucospoides oviposit inside the eggs and 1st instar larvae of woodwasps, which are burrowed deep inside the xylem tissue of pines. It is well known that I. leucospoides uses chemical cues, derived from a fungal symbiont of S. noctilio, to locate host eggs and larvae within a tree (Madden 1968;Spradbery 1974;Martínez et al 2006). Adults emerge, usually a year later, with a high number of mature eggs (~500, Fischbein 2011).…”

“…The mycelium used in the bioassays was excised from the culture dishes into 170 mm discs. The fungus culture was used as a chemical signal of possible oviposition sites to I. leucospoides (Martínez et al 2006). …”

“…All insects (hosts and parasitoids) were collected from the cages every day during their flight season. Spores of the symbiotic fungus Amylostereum areolatum were extracted from female woodwasp mycangia (Thomsen and Harding 2010), and were left to grow naturally in a culture medium based in agar agar, malt, yeast and pine extract (Martínez et al 2006). Cultures were maintained during 2-3 weeks inside a dark cabinet, at room temperature (17-25°C), before use in the experiments.…”

Patch choice from a distance and use of habitat information during foraging by the parasitoid Ibalia leucospoides

“…A great variety of environmental cues, such as chemical, visual and physical cues, are used by parasitoids as sources of information for both locating and assessing host patches (Vet & Dicke, 1992; Godfray, 1994). These cues of various natures can act as indicators of host presence, host species (Thiel & Hoffmeister, 2006) and host density (Waage, 1979; Li et al , 1997; Shaltiel & Ayal, 1998; Wang & Keller, 2004; Tentelier et al , 2005; Martínez et al , 2006, Corley et al , 2010), as well as of the presence of competitors in the current patch (Janssen et al , 1995a,b; Bernstein & Driessen, 1996; Castelo et al , 2003). The use of such information is expected to reduce uncertainty and therefore improve foraging success.…”