The Role of Semiochemicals in the Avoidance of the Seven-Spot Ladybird, Coccinella septempunctata, by the Aphid Parasitoid, Aphidius ervi

Abstract

The role of semiochemicals in mediating intraguild interactions between the seven-spot ladybird, Coccinella septempunctata, and the aphid parasitoid, Aphidius ervi, was investigated. Female parasitoids avoided leaves visited by C. septempunctata adults and larvae during the previous 24 hr. Ethanol extracts of C. septempuntata adults and larvae also induced avoidance responses by A. ervi. Two of the hydrocarbons identified by gas chromatography (GC) and coupled GC-mass spectrometry (GC-MS), n-tricosane (C23H48), and n-pentacosane (C25H52), when tested individually at levels found in the adult extract, induced avoidance by A. ervi. Further investigation of the larvae extract, and footprint chemicals deposited by adults in glass Petri dishes, confirmed the presence of the hydrocarbons. Parasitism rates of the pea aphid, Acyrthosiphon pisum, on broad bean plants, Vicia faba, which had been sprayed with a mixture of the chemicals, were lower than those on control plants. The effect, however, was no longer evident if parasitoid foraging was delayed by 24 hr after the plants were treated. The ecological significance of intraguild avoidance behavior and implications for possible use of the semiochemicals involved in future biological control programs are discussed.

Foraging in a complex environment - semiochemicals support searching behaviour of the seven spot ladybird

“…1-9) and n-pentacosane ( Fig. 1-10) (Nakashima et al, 2004). A similar mechanism has been described for the relationship between the aphid parasitoid, A. colemani and C. septempunctata, Harmonia axyridis and Propylea japonica, where the number of eggs deposited in colonies with coccinellid larvae was reduced in the presence of semiochemicals from the larval tracks of C. septempunctata.…”

Intraguild interactions between the predatory hoverfly Episyrphus balteatus (Diptera: Syrphidae) and the Asian ladybird, Harmonia axyridis (Coleoptera: Coccinellidae): Effect of larval tracks

“…parasitoids and predators) avoid ovipositing where competitors threaten the survival of their offspring by responding to the semiochemicals released by conspecific competitors. For example parasitoids are sensitive to volatiles signaling the previous or actual presence of conspecifics and to chemical trails deposited by their enemies (Price, 1970;Janssen et al, 1995;Nakashima et al, 2004). Several aphidophagous and coccidophagous predators respond to ovipositiondeterring semiochemicals in the tracks left by conspecific larvae (Merlin et al, 1996;RĤžiþka, 1997RĤžiþka, , 2002RĤžiþka, , 2006Doumbia et al, 1998;Hemptinne et al, 2001).…”

Temporal and within-plant distribution of the parasitoid and predator complexes associated with Acyrthosiphon pisum and A. kondoi (Homoptera: Aphididae) on alfalfa in Japan

“…For instance, intraguild predation (IGP), trophic interactions between natural enemies sharing the same resource, may be common in agroecosystems and may influence the level of herbivore population suppression (Rosenheim et al, 1993Rosenheim, 1998;Raymond et al, 2000). Interactions between various combinations of intraguild natural enemies associated with aphids are known, such as IGP between parasitoids (Mackauer, 1990), between predators (Wheeler, 1977;Atim and Graham, 1984), between predators and parasitoids (Wheeler et al, 1968;Colfer and Rosenheim, 1995;Wells et al, 2001;Nakashima and Senoo, 2003;Nakashima et al, 2004) and between entomopathogens and parasitoids (Powell et al, 1986;Brooks, 1993). Thus, identifying the spatio-temporal patterns of each member of an aphidophagous guild is important to assess the functional role of the guild in controlling aphid abundance.…”