This study was conducted to monitor the susceptibility status of Aedes aegypti (Linnaeus) larvae in the Sunda Islands of Indonesia against various organophosphates and organochlorines. Larval bioassay was performed in accordance with the World Health Organization standard protocol. Field-collected and reference strains of Ae. aegypti larvae were tested against diagnostic doses of eight larvicides belonging to organophosphates and organochlorines, namely bromophos (0.050 mg/liter), chlopyrifos (0.002 mg/liter), fenitrothion (0.020 mg/liter), fenthion (0.025 mg/liter), malathion (0.125 mg/liter), temephos (0.012 mg/liter), DDT (0.012 mg/liter), and dieldrin (0.025 mg/liter). Mortality rates of larvae were recorded at 24-h posttreatment. This study showed that Ae. aegypti larvae from Padang, Samarinda, Manggarai Barat, and South Central Timor were susceptible to both fenitrothion and dieldrin (mortality rates ≥ 98%). About 6 out of 10 field strains of Ae. aegypti larvae were resistant (<80% mortality rates) against fenthion, whereas Ae. aegypti larvae from Kuningan, Samarinda, Sumba, and South Central Timor exhibited some degrees of resistance (mortality rates 80-98%). All field-collected Ae. aegypti larvae were resistant against diagnostic doses of chlorpyrifos, malathion, temephos, and DDT with mortality rates ranging from 0 to 74.67%. Continued insecticide susceptibility studies are essential to identify the efficacy of insecticides for an improved dengue vector control and to delay the development of insecticide resistance.
A new simuliid species, Simulium kalimantanense sp. nov., is described on the basis of females, males, pupae, and mature larvae from East Kalimantan, Indonesia, and is assigned to the Simulium banauense species-group of Simulium (Gomphostilbia). This new species has close similarities to S alienigenum Takaoka from the Philippines, in many characters including the adult antennal color pattern and pupal gill with four long filaments arranged in two pairs each bearing a long stalk, but is distinguished from the latter in the female by the longer sensory vesicle and in the pupa by the gill with an elongate common basal stalk. Simulium kalimantanense sp. nov. is the first member of the S. banauense group in Borneo, and marks the most southerly distribution of the group. Keys to identify 19 Bornean species of the subgenus Gomphostilbia are provided.
Aedes aegypti (L.) (Diptera: Culicidae) is the primary vector of several arthropod-borne viral infectious diseases globally. Relentless vector control efforts are performed to curtail disease transmissions, insecticides remain as the first line of defense in Indonesia. With a dearth of publication on the efficacy of mosquito coil in Indonesia, this is the first report related to mosquito coil despite its common use in households. Ae. aegypti mosquitoes were sampled from nine regencies in Indonesia and tested using the glass-chamber method against three commercially available local pyrethroid-based mosquito coils containing d-allethrin, transfluthrin, and metofluthrin. The 50% knockdown time of female Ae. aegypti tested with d-allethrin, transfluthrin, and metofluthrin containing coils ranged from 0.65 to 14.32; 0.8 to 16.4; and 0.78 to 20.57 min, respectively. Mortality rates in accordance with WHO resistance indicators showed that strains from Denpasar, Mataram, Kuningan, Padang, Samarinda, and Sumba Timur were resistant (<80% mortality rate), whereas strains from Manggarai Barat, Dompu, and Pontianak were susceptible (>98% mortality rate) to the active ingredients assayed. Moreover, the knockdown rates between d-allethrin and transfluthrin, d-allethrin and metofluthrin, as well as transfluthrin and metofluthrin displayed significant associations, portraying the presence of cross-resistance within pyrethroid insecticides. The minimal insecticidal effect of mosquito coils against some Indonesian Ae. aegypti also pointed out the development of pyrethroid resistance, prompting a revamping of the vector control system.