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| Author(s): |
Rafael de Andrade Moral
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 2014-01-27 |
| Examining board members: |
Clarice Garcia Borges Demetrio;
Wesley Augusto Conde Godoy;
Afrânio Márcio Corrêa Vieira
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| Advisor: | Clarice Garcia Borges Demetrio |
| Abstract | |
Several studies have verified the relations among the fall armyworm, Spodoptera frugiperda, as well as the cotton leafworm, Alabama argillacea, and potential biological control agents, as they are important pests of several crops. Research with parasitoids and predators of different orders has been developed with this purpose. The ring-legged earwig (Euborellia annulipes) shows great potential, as well as the Neotrpical stink bug (Podisus nigrispinus), as they are natural enemies of these pests. The parasitoid wasp Campoletis flavicincta is also considered a biological control agent of S. frugiperda. Four experiments were set up and conducted to characterize the ecological relations among the described species: i) competition between the predators for S. frugiperda larvae; ii) competition between the predators for A. argillacea larvae; iii) intraspecific competition among the predators\' nymphs; iv) choice tests between S. frugiperda larvae that were previously parasitised by C. flavicincta and larvae that were not. Statistical models of different types were fit to the data. Generalized linear models were used to analyse univariate discrete data (counts and proportions), survival analysis models were used to analyse time-until-event data, generalized additive models and ordered multinomial logistic models were used to analyse mortality rates through time. To assess goodness-of-fit, functions that produce half-normal plots with a simulation envelope were implemented for the open-source software R. It was observed that females of E. annulipes are less aggressive and this species has a competitive advantage over P. nigrispinus, and may act as an intraguild predator. Besides that, the predators are able to distinguish parasitised from non-parasitised S. frugiperda larvae, and there are evidence that show that males tend to avoid feeding on larvae parasitised by C. flavicincta. Females, however, have no prefference and may indirectly feed on the parasitoid when predating a parasitised larva, and this might be a stabilizing factor in this system. In addition, coexistence among the pest, predators and parasitoid is most likely when predation rates are high and parasitism rates are low. (AU) | |
| FAPESP's process: | 11/15253-6 - Statistical and ecological modeling of trophic relations among pests and natural enemies |
| Grantee: | Rafael de Andrade Moral |
| Support Opportunities: | Scholarships in Brazil - Master |