An inventory of human night-biting mosquitoes and their bionomics in Sumba, Indonesia

Abstract

Mosquitoes are important vectors that transmit pathogens to human and other vertebrates. Each mosquito species has specific ecological requirements and bionomic traits that impact human exposure to mosquito bites, and hence disease transmission and vector control. A study of human biting mosquitoes and their bionomic characteristics was conducted in West Sumba and Southwest Sumba Districts, Nusa Tenggara Timur Province, Indonesia from May 2015 to April 2018. Biweekly human landing catches (HLC) of night biting mosquitoes both indoors and outdoors caught a total of 73,507 mosquito specimens (59.7% non-Anopheles, 40.3% Anopheles). A minimum of 22 Culicinae species belonging to four genera (Aedes, Armigeres, Culex, Mansonia), and 13 Anophelinae species were identified. Culex quinquefasciatus was the dominant Culicinae species, Anopheles aconitus was the principal Anopheles species inland, while An. sundaicus was dominant closer to the coast. The overall human biting rate (HBR) was 10.548 bites per person per night (bpn) indoors and 10.551 bpn outdoors. Mosquitoes biting rates were slightly higher indoors for all genera with the exception of Anopheles, where biting rates were slightly higher outdoors. Diurnal and crepuscular Aedes and Armigeres demonstrated declining biting rates throughout the night while Culex and Anopheles biting rates peaked before midnight and then declined. Both anopheline and non-anopheline populations did not have a significant association with temperature (p = 0.3 and 0.88 respectively), or rainfall (p = 0.13 and 0.57 respectively). The point distribution of HBR and seasonal variables did not have a linear correlation. Data demonstrated similar mosquito–human interactions occurring outdoors and indoors and during early parts of the night implying both indoor and outdoor disease transmission potential in the area–pointing to the need for interventions in both spaces. Integrated vector analysis frameworks may enable better surveillance, monitoring and evaluation strategies for multiple diseases.

Bionomics, seasonal abundance and insecticide susceptibility of Anopheles (Diptera: Culicidae) in low and high malaria transmission settings in Ethiopia

“…The weak positive non-significant association between mosquito density and rainfall could obviously be due to the biology of lag time in addition to the destruction of mosquito larval habitats by floods and water currents created by heavy rainfall which reduced adult mosquito abundance during heavy rains. Weak non-significant positive associations between mosquito abundance and some climatic factors, including humidity [51], rainfall and temperature [52] were also reported in other studies.…”

Bionomics, seasonal dynamics and insecticide susceptibility of Anopheles mosquitoes in low and high malaria transmission settings of Ethiopia

“…In another study, a positive association between relative humidity with mosquito abundance with no signi cance correlation with temperature and rainfall was reported from Balngladesh [21].. In another study, presence of weak correlation between mosquito abundance and some climatic factors including rainfall and temperature has also been reported [42]. In contrast, [43] stated that there was no any correlation between rainfall and Anopheles mosquitoes in a study conducted in Malaysia-Thailand border.…”

Impact of a spatial repellent intervention on Anopheles kdr insecticide resistance allele in Sumba, Indonesia

“…Of the 12 Anopheles species that were found to carry the kdr allele, 11 species are reported as human night-biting mosquitoes in Sumba [ 47 ] and confirmed as malaria vectors [ 10 , 28 ] Homozygous, heterozygous, and heteroduplex forms of kdr alleles were found in these species and likely reflect different molecular evolution dynamics combined with different insecticide exposure levels in each Anopheles species. The dynamics of resistance acquisition and spread may be linked to many factors, including the history of insecticide use, the level of pre-existing susceptibility to the compound, the frequency and heritability of genes related to resistance, and the co-selection of distinct resistance mechanisms in the same population [ 13 ].…”