Identification of Behaviourally Active Components from Maize Volatiles for the Stemborer Parasitoid Cotesia Flavipes Cameron (Hymenoptera: Braconidae)

In the present study, Y-tube olfactometric assays confirmed that volatiles from maize seedlings infested with Chilo partellus larvae were more attractive to the borer’s larval endoparasitoid Cotesia flavipes, than volatiles from uninfested maize. Coupled gas chromatography-electroantennographic detector (GC-EAD) analysis of the volatiles from larvae-infested maize revealed six electrophysiologically active compounds on the antennae of the female parasitoid. These compounds were identified by GC-MS as (Z)-3-hexenyl acetate, linalool, (E)-4, 8-dimethyl-1, 3, 7-nonatriene, heptanal, (E)-ß-ocimene and a C-5 aliphatic compound. (E)-4, 8-Dimethyl-1, 3, 7-nonatriene was present in EAG-detectable amounts in the volatiles of uninfested seedlings. In bioassays, a blend comprised of (Z)-3-hexenyl acetate, linalool, (E)-4, 8-dimethyl-1,3,7-nonatriene, (E)-ß-ocimene and heptanal was significantly attractive to the parasitoid. Of the individual compounds, (Z)-3-hexenyl acetate was attractive at the doses tested while (E)-4,8-dimethyl-1,3,7-nonatriene and heptanal showed varying degree of attractiveness to the parasitoid at different doses. Linalool and (E)-ß-ocimene were unattractive at the same doses. The significance of these results is discussed.RésuméDans cette étude, des essais olfactométriques en tubes Y ont confirmé que les matières volatiles de jeunes plants de maïs infestés par des larves du foreur de tige, Chilo partellus attiraient plus de larves de Cotesia flavipes un endoparasitoïde de ce foreur, en comparaison des matières volatiles du maïs non infesté. L’analyse par chromatographie à phase gazeuse couplée avec un détecteur électro-antennographique des matières volatiles du maïs infesté de larves a révélé six composés avec des activités éléctro-physiologiques sur les antennes de la femelle du parasitoïde. Ces composés ont été identifiés par méthodes GC-MS comme (Z)-3-hexényle acétate, linalol, (E)-4, 8-diméthyle-1,3,7-nonatriène, heptanal, (E)-ß-ocimène et un autre composé, le C-5 aliphatique. (E)-4, 8-diméthyle-1,3,7-nonatriène était présent en quantités détectables par méthode EAG, dans les matières volatiles de jeunes plants non infestés. Au cours des essais biologiques, un cocktail fait de (Z)-3-hexényle acétate, de linalool, de (E)-4,8-diméthyle-1,3,7-nonatriène, de (E)-ß-ocimène et d’heptanal, attirait fortement le parasitoïde. Quant aux différents composés pris isolément, (Z)-3-hexényle acétate était attrayant aux doses testées tandis que (E)-4, 8-diméthyle-l, 3, 7-nonatriène et heptanal montraient des degrés variables d’attractivité à différentes doses. Le linalol et (E)-ß-ocimène ne montraient pas d’attrait aux mêmes doses. L’article discute de la signification des résultats obtenus.

[1]  Han Olff,et al.  Herbivores Between Plants and Predators , 1999 .

[2]  Louise E. M. Vet,et al.  Plant-carnivore interactions: evolutionary and ecological consequences for plant, herbivore and carnivore , 1999 .

[3]  F. Bigler,et al.  The Induction of Volatile Emissions in Maize by Three Herbivore Species with Different Feeding Habits: Possible Consequences for Their Natural Enemies , 1998 .

[4]  R. Yamaoka,et al.  Plant Effects on Parasitoid Foraging: Differences between Two Tritrophic Systems , 1998 .

[5]  R. Jobidon.  Comparative Efficacy of Biological and Chemical Control of the Vegetative Reproduction inBetula papyriferaandPrunus pensylvanica , 1998 .

[6]  Christine Woodcock,et al.  Intercropping increases parasitism of pests , 1997, Nature.

[7]  W. Overholt,et al.  Host Location and Acceptance byCotesia flavipesCameron andC. sesamiae(Cameron) (Hymenoptera: Braconidae), Parasitoids of African Gramineous Stemborers: Role of Frass and Other Host Cues , 1997 .

[8]  B. Torto,et al.  Seasonal variation in the essential oil composition of Commiphora quadricincta and its effect on the maturation of immature adults of the desert locust, Schistocerca gregaria , 1997 .

[9]  C. Omwega,et al.  A review of the introduction and establishment of cotesia flavipes cameron in east africa for biological Control of Cereal Stemborers , 1997 .

[10]  C. Omwega,et al.  Evidence of the establishment of Cotesia flavipes (Hymenoptera: Braconidae) in continental Africa. , 1995 .

[11]  A. Ngi-Song.  Parasitization of Selected African Stemborers By Cotesia Flavipes Cameron and Cotesia Sesamiae (Cameron) (Hymenoptera:Braconidae) with Emphasis on Host Selection and Host Suitability. , 1995 .

[12]  M. Dicke,et al.  Volatiles from damaged plants as major cues in long‐range host‐searching by the specialist parasitoid Cotesia rubecula , 1994 .

[13]  W. Lewis,et al.  Learning of Host-Finding Cues by Hymenopterous Parasitoids , 1993 .

[14]  Ted C. J. Turlings,et al.  The semiochemical complexes that mediate insect parasitoid foraging , 1992 .

[15]  W. J. Lewis,et al.  Larval‐damaged plants: source of volatile synomones that guide the parasitoid Cotesia marginiventris to the micro‐habitat of its hosts , 1991 .

[16]  H. Young,et al.  Attraction of the grasshopper, Melanoplus sanguinipes, to host plant odors and volatile components , 1990 .

[17]  J. Visser.  Host Odor Perception in Phytophagous Insects , 1986 .

[18]  F. James Rohlf,et al.  Biometry: The Principles and Practice of Statistics in Biological Research , 1969 .

[19]  B. Ephrussi,et al.  A Technique of Transplantation for Drosophila , 1936, The American Naturalist.