Stomoxys calcitrans: feno de alfafa como substrato larval e atividade adulticida do óleo de Melaleuca alternifolia com alto teor de 1,8-cineole

Abstract

Stomoxys calcitrans (Linnaeus, 1758), know as stable fly, belonging to Muscidae family, genus Stomoxys, is a hematophagous dipteran responsible for causing performance and productive losses in horses and cattle, as well as causing health impacts through the dissemination of pathogenic microorganisms. Currently, the control of this fly make use of synthetic insecticides, sanitary management, biological control and traps, but none of these methods alone is effective. The frequent outbreaks in Brazil, related mainly to the expansion of sugarcane plants, demonstrate the need to seek alternatives to conventional control and a promising option are the essential oils, which have been widely studied in relation to their insecticidal activities. The first study aimed at the effects of alfalfa hay as a substrate for the development and survival of larval stages up to adult stage of the stable fly, in order to maintain colonies in laboratory and further conduct bioassays for the control of this insect. For this, 65 eggs were collected from a colony established in laboratory and placed on a larval substrate containing alfalfa hay (100g) and distilled water (200ml), replicated six times. The mean number of days for egg hatching was 1.4 (± 0.5), the larval period was 11.33 days (± 1.75) and the pupal period was 5.83 days (± 0.51). The complete cycle from egg to adult was 18.66 days (± 2.06). The mean larval viability was 91.03% (± 3.14), pupation 88.71% (± 3.17) and the percentage of emergence (pupae to adults) was 91.13% (± 3.0). The results obtained in the present work indicated that the use of larval substrate with alfalfa hay allowed the development of immature stages of S. calcitrans in laboratory, demonstrating good percentages of larval development, pupation and emergence of adults. The second study aimed to investigate the insecticidal activity of the oil of Melaleuca alternifolia, with a high content of 1,8- cineole, to the S. calcitrans specie. By the method of impregnated paper, it was possible to observe that the treatments of 25 and 50 μg/cm2 (p> 0.05) showed fumigant action. The mortality rate in relation to the time of exposure to oil after treatments was better compared to Diazinon between treatments of 25 and 50 μg/cm2 (96.6 ± 3.3% and 100 %, respectively) in the first 15 minutes. In superficial application test, the only treatment that demonstrated adulticidal action was 5% (p> 0.05). The lethal concentration, LC50 (%; w/v) was 1.06 ± 0.02 and 3.82 ± 0.65 for the impregnated paper and surface application methods, respectively. Thus, M. alternifolia essential oil has a potential for adulticidal action against S. calcitrans.