Effect of an extract from Plumbago scandens L. (malacara) on Chrysomya putoria post-embryonic development

Julio César EScalona Arranz

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Introduction: excessive use of chemical insecticides for pest control has become a dangerous practice, for these products may affect both human beings and animals. This is the reason why the development of biopesticides has gained great importance. Plumbago scandens L. (malacara) is a medicinal plant producing large amounts of plumbagin, a compound with high larvicidal activity against mosquitoes.
Objective: evaluate the toxicity / selectivity of a P. scandens extract (PSE) on the post-embryonic development of the Chrysomya putoria fly.
Methods: a crude extract was prepared from dry roots of the species by Soxhlet extraction in n-hexane. Chemical identification of plumbagin in the extract was based on GC/MS. Three concentrations (25 %, 50 % and 75 %) were evaluated, monitoring the viability and duration of each stage in the life cycle of the fly (larval, pupal and development until adulthood). An evaluation was also conducted of the effects on the weight of mature larvae and the sex ratio.
Results: none of the PSE concentrations evaluated differs from the control group at the larval or pre-adulthood development stages, but they do differ slightly at the pupal stage in the 25 % and 50 % groups. There were no variations in the sex ratio, but differences were found in larval weight, which was lower in the 50 % and 75 % groups.
Conclusion: the PSE does not have a relevant effect on any of the stages in the lifecycle of the fly. Therefore, it is not declared to be toxic on the biological model used, thus meeting one of the most important attributes of a biopesticide: its biological selectivity.