Using ecological niche models to describe the geographical distribution of the myiasis-causing Cochliomyia hominivorax (Diptera: Calliphoridae) in southern South America.

In southern South America, namely Argentina and Chile, Cochliomyia hominivorax (Coquerel) is the main myiasic agent on humans and domestic animals. The distribution pattern of the species is poorly known and the southern limit of its geographic distribution is unclear. The aims of this study are to elucidate the basic environmental factors associated with occurrence of this myiasic species, evaluation of models constructed on the basis of occurrence data based on adult specimen records to predict geographic occurrence of myiasis, evaluation of unsurveyed sites of high potential of occurrence of the species, and recognition and prioritization of areas that need medical control and specific prophylaxis practices related to this pest. The maximum entropy modeling system (Maxent) was used. Maps of potential distribution of C. hominivorax were produced using two different datasets, models obtained with all localities known for the species (combining medical data and taxonomic data) and only-taxonomic models (excluding medical data). The results obtained include an updated compilation of occurrence of the species in Argentina and Chile. Predictive models obtained in this work indicated that large areas of central-eastern territory of Argentina has the potential for C. hominivorax occurrence, probably reaching the parallel 42° S as is indicated by the complete datasets. Only-taxonomic models fail to predict those myiasic cases occurring in the nearer areas of the Andean chains. The main variables associated with the distribution of C. hominivorax were, alternatively, isothermality or minimum temperature of the coldest month. These results provide a new analytical resource of high potential for the prevention of myiasis and to supports further epidemiological studies.