Fast Gas Chromatography Characterisation Of Purified Semiochemicals From Essential Oils Of Matricaria Chamomilla L. (Asteraceae) And Nepeta Cataria L. (Lamiaceae)

in Journal of Chromatography. A (2009), 1216(14), 2768-2775

Tomato-aphid-hoverfly: A tritrophic interaction incompatible for pest management

in Arthropod-Plant Interactions (2009), 3

Trichome-based tomato resistance offers the potential to reduce pesticide use, but its compatibility with biological control remains poorly understood. We evaluated Episyrphus balteatus De Geer (Diptera ... [more ▼]

Trichome-based tomato resistance offers the potential to reduce pesticide use, but its compatibility with biological control remains poorly understood. We evaluated Episyrphus balteatus De Geer (Diptera, Syrphidae), an efficient aphidophagous predator, as a potential biological control agent of Myzus persicae Sulzer (Hemiptera, Aphididae) on trichome-bearing tomato cultivars. Episyrphus balteatus’ foraging and oviposition behavior, as well as larval mobility and aphid accessibility, were compared between two tomato cultivars (Lycopersicon esculentum Mill. ‘Moneymaker’ and ‘Roma’) and two other crop plants; broad bean (Vicia faba L.) and potato (Solanum tuberosum L.). Hoverfly adults landed and laid more eggs on broad beans than on three species of Solanaceae. Hoverfly larval movement was drastically reduced on tomato, and a high proportion of hoverfly larvae fell from the plant before reaching aphid prey. After quantifying trichome abundance on each of these four plants, we suggest that proprieties of the plant surface, specifically trichomes, are a key factor contributing to reduced efficacy of E. balteatus as a biological agent for aphid control on tomatoes. [less ▲]

Aphid honeydew is not only a sugary and amino-acid secretion

Poster (2008)

Aphids, feeding from the phloem sap of plants, are the most common honeydew producing insects. This aphid excretory product consists in an aqueous mixture of different chemical compounds of which the most ... [more ▼]

Aphids, feeding from the phloem sap of plants, are the most common honeydew producing insects. This aphid excretory product consists in an aqueous mixture of different chemical compounds of which the most important are sugars (90-95% of the dry weight) and amino acids. This excretory product, used by parasitoids and predators, plays a crucial role in the tritrophic interactions : (1) honeydew is an important food complement and (2) honeydew acts as a volatile and a contact kairomone. These characteristics could be exploited for enhancing the biological control in fields through the use of an « artificial honeydew ». [less ▲]

La coccinelle à deux points (Adalia bipunctata), le chrysope commun (Chrysoperla carnea) et le syrphe ceinturé (Episyrphus balteatus), nos principaux prédateurs indigènes plutôt que la coccinelle asiatique (Harmonia axyridis) exotique et invasive dans nos écosystèmes

in L'Erable du CNB (2008)

What makes Episyrphus balteatus (Diptera: Syrphidae) oviposit on aphid infested tomato plants?

in Communications in Agricultural and Applied Biological Sciences (2008), 73(3), 371-81

Under attack by insect pests, many plant species change their volatile chemical emissions to attract natural enemies. Most of the tomato (Lycopersicon sp., Solanaceae) varieties are subjected to ... [more ▼]

Under attack by insect pests, many plant species change their volatile chemical emissions to attract natural enemies. Most of the tomato (Lycopersicon sp., Solanaceae) varieties are subjected to infestation by molluscs and insects, including the generalist aphid Myzus persicae Sulzer (Homoptera, Aphididae). Episyrphus balteatus De Geer (Diptera: Syrphidae) is a generalist aphid predator that was here observed to lay eggs on M. persicae infested tomato but not on non-infested plants. In order to identify the volatile chemicals that guide the foraging and oviposition behaviour of E. balteatus, we collected and identified volatiles released in the headspace of both aphid infested and uninfested tomato plants by SPME-GC-MS. The identified chemicals were subsequently tested by electroantennography (EAG) on E. balteatus. Monoterpenes and sesquiterpenes were identified, the main volatile chemicals being beta-phellandrene, 2-carene, alpha-phellandrene, 3-carene and o-pinene. Electrical depolarizations were observed for each tested monoterpene, with optimal responses ranging from -0.2 to -0.8 mV. Episyrphus balteatus antennae showed dose-response relationships towards all the active chemicals. (E)-beta-farnesene, the main component of the aphid alarm pheromone, was the only active sesquiterpene, and is presumed to act as an oviposition stimulus for E. balteotus. [less ▲]