Maize induced volatiles elicited by a host Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) and a non-host Plutella xylostella L. (Lepidoptera: Plutellidae) of these insects and their respective parasitoids

Author(s)

André Gustavo Corrêa Signoretti

• Document type: Master's Dissertation
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2008-10-06

Examining board members

José Maurício Simões Bento; André Luiz Lourenção; José Djair Vendramim

• Advisor: José Maurício Simões Bento

Abstract

Plants recognize and produce specific volatile substances that attract parasitoids after the herbivore attack, characterizing a process known as indirect defense. However, the ability of these plants in processing and releasing novel volatile compounds elicited by a non-host herbivore attack has been poorly explored. Regarding this, the current study aimed to investigate the effect of volatiles emitted by maize plants under the attack of a pest which is not a host so far, diamondback moth, Plutella xylostella compared to those emitted by a common host, fall armyworm, Spodoptera frugiperda on the behavior response of these insects and their respective parasitoids Apanteles piceotrichosus e Campoletis flavicincta. The bioassays with the parasitoids were conducted during photophase and they were exposed to volatiles from undamaged maize, volatiles released at the time intervals 0-1, 5-6 and 24-25h after the treatment of mechanical damage or simulated herbivory during photophase, and volatiles released at the time interval 5-6h after these same treatments in scotophase. The bioassays with the moths were carried out in scotophase and they were exposed to volatiles from undamaged maize, volatiles released at the time interval 5-6h after the treatment of mechanical damage or simulated herbivory during photophase, and volatiles released at time intervals 0-1 and 24-25h after these same treatments in scotophase. Additionally, for P. xylostella volatiles from undamaged kale were tested while for A. piceotrichosus it was tested volatiles from undamaged kale, mechanically damaged and P. xylostella caterpillar damaged kale. C. flavicincta females were attracted to volatiles emitted by the maize plants at the interval 5-6h after the treatment with the S. frugiperda regurgitate in scotophase. Curiously, they were not attracted to volatiles released at the same time interval after the induction elicited by the regurgitate in the photophase. S. frugiperda mated females were attracted by volatiles from undamaged plants and volatiles released at time intervals 5-6 and 24- 25h after the mechanical damage or treated with the regurgitate of this herbivore. Nevertheless, they preferred the volatiles from undamaged maize to the plants treated with the regurgitate during photophase. These results demonstrated that these insects are able to distinguish among the volatile blends present in their natural habitat where it occurs the tritrophic relationship maize (host plant) S. frugiperda (herbivore) C. flavicincta (parasitoid). In the same way, in the relationship kale (host plant)- P. xylostella (herbivore) A. piceotrichosus (parasitoid), P. xylostella females were attracted by the volatiles of undamaged kale as well as the A. piceotrichosus females were attracted to volatiles emited by caterpillar-damaged kale. In the case of simulating a new relationship, maize (non-host plant) P. xylostella (herbivore) C. flavicincta (parasitoid), A. piceotrichosus females and P. xylostella were not able to respond to undamaged maize, mechanically damaged and mechanically damaged+ P. xylostella regurgitate. The determination of these mechanisms can be useful for a better understanding of the evolution context between plants and insects and for obtaining new advances in the management and biological pest control. (AU)