Impact of peri-urban pig farms on mosquito community structure in Yogyakarta, Indonesia

Livestock-keeping in peri-urban areas might influence mosquito-borne diseases by attracting more mosquitoes or by diverting mosquitoes from feeding on humans. In this study, we compared the mosquito community structure across pig farms, human settlements around pig farms, and human settlements without pig farms in peri-urban areas of Yogyakarta. We collected mosquitoes using ultraviolet light traps from three large pig farms (10 traps), 120 human settlements near pig farms (20 traps), and 120 human settlements without pig farms (20 traps) in Yogyakarta. The adult mosquitoes were morphologically identified using taxonomic keys. Polymerase chain reaction was used only to identify damaged and unidentified mosquito specimens using the cytochrome c oxidase subunit 1 gene marker. A total of 2253 adult mosquitoes (1663 females and 590 males) belonging to 26 species were collected from large pig farms, human settlements near pig farms, and human settlements without pig farms. Permutational multivariate analysis of variance revealed significant differences in mosquito community structure between the three areas (R² = 0.66, P = 0.001). Large pig farms had higher mosquito diversity (26 species) than human settlements near pig farms (17 species) and human settlements without pig farms (10 species), with the highest number of Japanese encephalitis vector, Culex tritaeniorhynchus (381 individuals) collected in large pig farms and some zoophilic mosquitoes (e.g. Anopheles vagus, An. aconitus, An. barbirostris, Mansonia uniformis, Mn. annulata, Cx. tritaeniorhynchus, Cx. hutchinsoni, and Mimomyia luzonensis) found in human settlements near pig farms. Artificial containers for animal drinking were found to be breeding sites for Aedes aegypti, Ae. albopictus, and Culex quinquefasciatus in large pig farms. Raising pigs near human settlements increases the diversity and density of mosquito species, as demonstrated in our study, which also identifies pig farms as potential breeding sites for mosquitoes and highlights the higher risk of emergence of mosquito-borne diseases. Our data highlight the increased risk of Japanese encephalitis (JE) transmission in areas near pig farms and suggest that livestock relocation from human settlements and management practices to control mosquito breeding sites in pig farms in peri-urban areas could reduce the risk of disease outbreaks.