Abstract

The Mediterranean fruit fly Ceratitis capitata (Diptera: Tephritidae) is a serious threat for the Bolivian fruit sector. Despite its importance, few efforts have focussed on the development of alternative techniques to broad spectrum pesticides, especially those that suppress the pest using odour-mediated behavior manipulation. In this thesis, I explored whether such odor-based control techniques, using locally available attractants and repellents, could be developed. In laboratory and field trials, ‘chicha’, a corn-based fermented beverage was more attractive than commercial baits to C. capitata. However, non-target insects constituted a large portion of the trap catches. A series of traps based on waste material were designed and tested in combination with chicha. One prototype was comparable in captures with the commercial Tephritrap, while at the same time being more selective. In parallel, laboratory screening followed by semi-field and field trials were used to evaluate the effect of essential oils on reducing attraction, oviposition and fruit infestation by C. capitata. Laboratory tests showed that the essential oils of three aromatic plants, Cymbopogon citratus, Tagetes filifolia and Schinus molle reduced attractiveness of oviposition substrates. In semi-field experiments these essential oils suppressed oviposition in peach, whereas in a field trial, S. molle oil mixed in dollops of biodegradable wax reduced infestation in peach orchards. Gas-chromatography coupled to electro-antennographic detection (GC-EAD) and electro-palpographic detection (GC-EPD), were used to characterize the volatile profile of essential oils (repellents) and chicha (food attractant) with the corresponding sensory responses to these. The three oils were all dominated by terpenoids and differed substantially in the classes of constituted compounds, their relative amounts and the pattern of antennal/palpal responses. For chicha volatiles, antennal and palpal sensory responses of three tephritid species C. capitata, Zeugodacus cucurbitae, Bactrocera dorsalis and the unrelated Drosophila melanogaster, overlapped considerably with volatiles that are conserved across fresh fruits. This lead to conjecture that these may have served as pre-adaptive bridges mediating shifts from ancestral rotting substrates to ripening fruit. However, responses to fermentation volatiles in tephritids also diverged with the ecological niche: specialist Z. cucurbitae was most divergent, whereas generalist B. dorsalis and C. capitata, though phylogenetically distant, showed convergent sensory responses. Based on volatiles of chicha, we composed a blend and tested this in the field. Although chicha was more attractive, the blend was highly selective to medfly. This study showed ethological methods for direct application in orchards against C. capitata, and an increasing understanding of tephitids evolutionary ecology based on olfactory sensitivity. Therefore, identification of volatile blends and mapping olfactory responses to these can support the development of more effective and species-specific attractants and repellents, with high potential for incorporation into IPM programs.

Keywords

attractant; repellent; Ceratitis capitata; Tephritidae; olfaction; trapping; integrated pest management; fermentation; evolutionary ecology

Published in

Acta Universitatis Agriculturae Sueciae
2019, number: 2019:45
ISBN: 978-91-7760-408-2, eISBN: 978-91-7760-409-9
Publisher: Department of Plant Protection Biology, Swedish University of Agricultural Sciences

SLU Authors

• Figueroa, Ilich

  • Department of Plant Protection Biology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Other Agricultural Sciences not elsewhere specified
Evolutionary Biology
Behavioral Sciences Biology


Permanent link to this page (URI)

https://res.slu.se/id/publ/100283