Uso de semioquímicos no controle de moscas varejeiras Chrysomya megacephala, (Fabricius, 1974) (Diptera: Calliphoridae): uma praga causadora da miíase

Abstract

The fly, Chrysomya megacephala (Fabricius, 1794) (Diptera: Calliphoridae), known as the eastern latrine fly, is a pest of interest to public health, in addition to being of veterinary importance for causing myiasis that affects humans and other animals. Thus, the present work aimed to evaluate the morphological and morphometric characteristics that allow to identify and sexually differentiate these insects; characterize the types and functions of the sensillae and finally evaluate the attractiveness of food sources in different periods of decomposition, aiming to determine the efficiency of compounds present in these food sources in the monitoring and control of C. megacephala. The research consisted of two stages: the first involved the taxonomic identification of specimens, morphometric analysis and morphophysiological characterizations of the sensillae. The second in the identification and evaluation of the behavioral influence of apneumones emitted by food sources at different stages of decomposition against the fly, C. megacephala. The morphological analysis of the specimens, dichotomous keys were used with the aid of a stereoscopic microscope, for morphometry, 100 C. megacephala flies, millimeter ruler, digital caliper and stereoscopic microscope were used. The morphophysiological evaluation of the sensilla was performed by scanning electron microscopy (SEM). From the aeration technique, volatile compounds present in food sources were extracted. The behavioral assessments of C. megacephala flies against food sources and synthetic standards were performed using a four-arm olfactometer. For the field tests, four treatments were used shrimp extract (48h), synthetic solution in concentrations 100 ppm and 50 ppm and control treatment). As a result, it was identified that the predominant species belong to the genus Chrysomya, family Calliphoridae and species C. megacephala. The morphometric analyzes showed that the females of C. megacephala are larger than the co-specific males in most of the variables analyzed. Scanning electron microscopy (SEM) it was found that the antennae of C. megacephala are formed by three segments, scape, pedicel , flagella and arista, five types of sensilla .present in the antennal segments were characterized, dimorphism was observed in the pedicel, flagellum and arista. The results of the behavioral bioassays with C. megacephala, demonstrated that the 48h shrimp extract elicited greater attraction in females, whereas, the co-specific males were more attracted to the control treatment, suggesting a possible repellency. t was also observed that the shrimp extracts in the different decomposition periods (0h, 24h and 48h) triggered the best residence times of the female flies. The results of the analyzes of the shrimp extract (48h) in gas chromatography coupled to an electroantenographic detector CG-EAG) and gas chromatography coupled to a flame ionization detector (CG-DIC) and gas chromatography coupled to mass spectrometry (CG-EM) demonstrated three bioactive compounds, identified as phenol, 2-nonanone and methyl disulfide. The behavioral evaluation of C.megacephala against synthetic standards showed that the compounds tested individually, in binary combination, did not show significant differences when compared with the control-treatment 0,01 (P>0,01 e P<0.01), in ternary combination showed a significant difference when compared with treatment- control 0,01 (P>0,01 e P<0.01). The analyzes (EAG) of the C. megacephala flies against the synthetic standards proved to be equivalent to those observed in the (48h) shrimp sample. In the field conditions, the shrimp extract (48h) and the ternary mixture of the synthetic patterns (50 ppm and 100 ppm) triggered greater attractiveness for the female flies. Of the total captured 324 specimens, 219 were identified as C. megacephala. These results demonstrate the potential use of these substances in traps, aiming at the monitoring and control of C. megacephala of integrated management.