Insect pests are one of the major factors limiting the production and the storage of agricultural products. The use of synthetic pesticides limits the damage of these pests. However, the effectiveness of these products is continually eroded by the development of resistance in these pests and serious health and ecological disadvantages were detected. It is clear that there is an urgent need for alternative control measures, which must be active against the pests, safe to humans and environmentally friendly. Evaluation of local plants as sources of protectants is one of the promising ways to fulfil this need. In this study the essential oil of four Chrysanthemum species (C. macrotum, C. trifurcatum, C. segetum and C. fuscatum) were evaluated for their insecticidal activity against Tribolium confusum using tow methods: fumigation and consumption. The essential was diluted in acetone to obtain the concentration of 1%. For the fumigant activity, 100 μl of the solution was applied on filter paper (1x2.5 cm), after evaporating the solvent, each filter paper was placed on the underside of the screw cap of a glass vial and was screwed tightly onto the vial containing ten adults of Tribolium confusum. Concerning the evaluation of the anti-appetent activity, 5 μl of each Chrysanthemum species essential oil were applied on flour disc (95% wheat semolina and 5% beer yeast). The control received only acetone and five replicates were set up for each treatment and control. The results showed that essential oil obtained from flowers of C. macrotum and those from leaves of C. trifurcatum have the highest fumigant activity and cause respectively the mortality of 48 and 40% against adults of T. confusum. The study of anti-appetent effect on larvae of T. confusum showed that C. segetum flowers essential oil has the significant feeding deterrent index (92.45±4.61) followed by the leaves essential oil obtained from C. fuscatum (71.20±19.22), without having a significant mortality on this larvae. The study of essential oil composition of the four Chrysanthemum species highlighted their richness on mono and sesqueterpenes that are known for their insecticidal activity. Though these findings are preliminary, they could represent the basis for further investigations on the questions raised in this work. In particular, additional research is needed to investigate the susceptibility of other stages of the insect life, such as pupae and eggs and to improve our understanding of how mono- and sesquiterpenoids act on insects. Practically, in view of a possible use of the most active mono- and sesquiterpenoids, it should be pointed out that longer exposure periods could be needed to bridge the tolerant phases of insects, some of which could be present at the time of application.

Insecticidal and anti-appetent activities of four Chrysanthemum species against Tribolium confusum Du Val (Coleoptera: Tenebrionidae)

FLAMINI, GUIDO;
2013

Abstract

Insect pests are one of the major factors limiting the production and the storage of agricultural products. The use of synthetic pesticides limits the damage of these pests. However, the effectiveness of these products is continually eroded by the development of resistance in these pests and serious health and ecological disadvantages were detected. It is clear that there is an urgent need for alternative control measures, which must be active against the pests, safe to humans and environmentally friendly. Evaluation of local plants as sources of protectants is one of the promising ways to fulfil this need. In this study the essential oil of four Chrysanthemum species (C. macrotum, C. trifurcatum, C. segetum and C. fuscatum) were evaluated for their insecticidal activity against Tribolium confusum using tow methods: fumigation and consumption. The essential was diluted in acetone to obtain the concentration of 1%. For the fumigant activity, 100 μl of the solution was applied on filter paper (1x2.5 cm), after evaporating the solvent, each filter paper was placed on the underside of the screw cap of a glass vial and was screwed tightly onto the vial containing ten adults of Tribolium confusum. Concerning the evaluation of the anti-appetent activity, 5 μl of each Chrysanthemum species essential oil were applied on flour disc (95% wheat semolina and 5% beer yeast). The control received only acetone and five replicates were set up for each treatment and control. The results showed that essential oil obtained from flowers of C. macrotum and those from leaves of C. trifurcatum have the highest fumigant activity and cause respectively the mortality of 48 and 40% against adults of T. confusum. The study of anti-appetent effect on larvae of T. confusum showed that C. segetum flowers essential oil has the significant feeding deterrent index (92.45±4.61) followed by the leaves essential oil obtained from C. fuscatum (71.20±19.22), without having a significant mortality on this larvae. The study of essential oil composition of the four Chrysanthemum species highlighted their richness on mono and sesqueterpenes that are known for their insecticidal activity. Though these findings are preliminary, they could represent the basis for further investigations on the questions raised in this work. In particular, additional research is needed to investigate the susceptibility of other stages of the insect life, such as pupae and eggs and to improve our understanding of how mono- and sesquiterpenoids act on insects. Practically, in view of a possible use of the most active mono- and sesquiterpenoids, it should be pointed out that longer exposure periods could be needed to bridge the tolerant phases of insects, some of which could be present at the time of application.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/208660
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