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17. The use of salivary α-amylase as an evolutionary solution to host selection in parasitoids

Author

Bichang’a, Gladys, primary, Da Lage, Jean-Luc, additional, Mailhan, Claire-Marie, additional, Marion-Poll, Frédéric, additional, Capdevielle-Dulac, Claire, additional, Zivy, Michel, additional, Balliau, Thierry, additional, Ru, Bruno Le, additional, Kaiser-Arnauld, Laure, additional, Juma, Gerald, additional, Maina, Esther, additional, and Calatayud, Paul-andré, additional

Published
2017
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19. Location, acceptance and suitability of lepidopteran stemborers feeding on a cultivated and wild host-plant to the endoparasitoid Cotesia flavipes Cameron (Hymenoptera: Braconidae)

Author

Fritz Schulthess, Bruno Le Ru, Onesmus B. Wanyama, Paul-André Calatayud, Juma Gerald, and Meshack Obonyo

Subjects
Y tube olfactometer, Busseola fusca, GC analyses, biology, Sesamia nonagrioides, Sesamia calamistis, Hymenoptera, Sorghum bicolor, plant volatiles, biology.organism_classification, Chilo, Parasitoid, Pennisetum purpureum, Stemborer, Agronomy, Chilo partellus, Insect Science, Botany, Sciomesa piscator, Ovipositor, Agronomy and Crop Science, Braconidae, Busseola phaia
Abstract

Maize fields in Africa are usually surrounded by land occupied by wild plants many of which harbor lepidopteran stemborer species not found on crops. It is not known if the exotic braconid parasitoid Cotesia flavipes , which was released in Kenya in 1993 against the invasive crambid Chilo partellus , searches for and attacks these borers in their natural habitats and whether they are suitable for parasitoid development. The objective of this study was to assess the relationship between acceptance and suitability of six stemborer species attacking cultivated sorghum ( C. partellus , Busseola fusca , Sesamia calamistis , and S. nonagrioides ) or Napier grass ( Busseola phaia and Sciomesa piscator ) to C. flavipes . Although all stemborer species were equally accepted for ovipositor probing by C. flavipes , only C. partellus and S. calamistis were suitable and produced parasitoids. In olfactometric bioassays, C. flavipes females were more attracted to stemborer-infested than uninfested plants. Analyses of the volatile compounds showed that they produced richer volatile profiles, mainly comprising C5–C6 alcohols, terpenoids, aromatic and aliphatic compounds, than uninfested plants. It can be concluded that stemborer species, that were accepted for oviposition but were unsuitable for parasitoid development, form a reproductive sink and that the exotic parasitoid would not establish in areas where these are the predominant species.

Published
2008

22. α-Amylase Mediates Host Acceptance in the Braconid Parasitoid Cotesia flavipes.

Author

Bichang'a G, Da Lage JL, Capdevielle-Dulac C, Zivy M, Balliau T, Sambai K, Le Ru B, Kaiser L, Juma G, Maina ENM, and Calatayud PA

Subjects
Animals, Arthropod Antennae drug effects, Arthropod Antennae physiology, Chromatography, High Pressure Liquid, Electrophoresis, Polyacrylamide Gel, Host-Parasite Interactions, Insect Proteins analysis, Insect Proteins metabolism, Larva drug effects, Larva physiology, Oviposition, Tandem Mass Spectrometry, Wasps growth & development, Zea mays metabolism, alpha-Amylases pharmacology, Wasps physiology, Zea mays parasitology, alpha-Amylases metabolism
Abstract

Foraging parasitoids use chemical signals in host recognition and selection processes. Although, the volatiles play a relevant role in the localization by parasitoids of their hosts feeding on plants, the host identification process for acceptance occurs mainly during contact between the parasitoid and its host where host products related to feeding activities, fecal pellets and oral secretions, play a crucial role. The purpose of this study was to identify the nature of the contact kairomone(s) that mediate the acceptance for oviposition of the parasitoid Cotesia flavipes Cameron (Hymenoptera, Braconidae), which was released in Kenya in 1993 to control the invasive crambid Chilo partellus (Swinhoe). Using host and non-hosts of C. flavipes, we showed that it is mainly the oral secretions of the larvae that harbour the active compound(s) that mediate host acceptance for oviposition by C. flavipes. Using an integration of behavioral observations and biochemical approaches, the active compound of the oral secretions was identified as an α-amylase. Using synthetized α-amylases from Drosophila melanogaster (an insect model for which syntheses of active and inactive α-amylases are available), we observed that the conformation of the enzyme rather than its catalytic site as well as its substrate and its degradation product is responsible for host acceptance and oviposition mediation of C. flavipes females. The results suggest that the α-amylase from oral secretions of the caterpillar host is a good candidate for an evolutionary solution to host acceptance for oviposition in C. flavipes.

Published
2018
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