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Abstracts - Izabela Thaís Fidelis Alves da Silva

ATTRACTION OF THE LARVAL PARASITOID Bracon vulgaris (ASHMEAD) (HYMENOPTERA: BRACONIDAE) TO BOLL WEEVIL-INDUCED COTTON VOLATILES

Izabela Thaís Fidelis Alves da Silva1, Diego Martins Magalhães2, Miguel Borges3, Raúl Alberto Laumann4, José Ednilson Miranda5, Carlos Henrique de Brito6 and Maria Carolina Blassioli-Moraes7*

1 Embrapa Recursos Genéticos e Biotecnologia; izabelathais@hotmail.com

2 Embrapa Recursos Genéticos e Biotecnologia; magalhaes.dmm@gmail.com 3 Embrapa Recursos Genéticos e Biotecnologia; miguel.borges@embrapa.com 4 Embrapa Recursos Genéticos e Biotecnologia; raul.laumann@embrapa.com 5 Embrapa Algodão; jose-ednilson.miranda@embrapa.br

6 Universidade Federal da Paraíba; chbritoufpb@gmail.com

7 Embrapa Recursos Genéticos e Biotecnologia; carolina.blassioli@embrapa.com

* Correspondence: carolina.blassioli@embrapa

Plants respond to herbivore attack by emitting volatile organic compounds that may attract herbivores’ natural enemies. The boll weevil, Anthonomus grandis (Boheman) (Coleoptera: Curculionidae) is the main pest on cotton crops in the Neotropical region. Its natural control in Brazil is performed by larval parasitoids, among which the ectoparasitoid Bracon vulgaris (Ashmead) (Hymenoptera: Braconidae) is the main biological agent responsible for reducing boll weevil population levels. Here we explore whether cotton volatiles provide important cues in the attraction of B. vulgaris. Y-Tube bioassays were carried out to evaluate the response of mated females of B. vulgaris to constitutive and boll weevil-induced cotton volatiles, using plants and air-entrainment extracts. Five combinations of bioassays were performed: (i) constitutive reproductive cotton plants vs. air, (ii) boll weevil-induced reproductive cotton plants vs. air, (iii) constitutive reproductive cotton extracts vs. hexane, (iv) boll weevil-induced reproductive cotton extracts vs. hexane and (v) constitutive reproductive cotton extracts vs. boll weevil-induced reproductive cotton extracts. Female parasitoids did not show preference when given a choice between constitutive cotton volatiles, either from plants and extracts, and control, air or hexane (2=0.85, p=0.35; 2=1.84, p=0.17). However, when boll weevil-induced cotton volatiles were compared against air (2=9.49, p=0.002), hexane (2=6.30, p=0.01) and constitutive reproductive cotton extracts (2=4.16, p=0.04), the parasitoids preferred herbivore-induced volatiles. Bioassays comparing constitutive against induced cotton plants volatiles are currently under investigation. The results demonstrate that B. vulgaris exploit cotton volatiles induced by A. grandis in searching for larval hosts.