Insecticide resistance status of Aedes aegypti and Aedes albopictus mosquitoes in Papua New Guinea

BACKGROUND

Aedes aegypti and Ae. albopictus are important vectors of infectious diseases, especially those caused by arboviruses such as dengue, chikungunya and Zika. Aedes aegypti is very well adapted to urban environments, whereas Ae. albopictus inhabits more rural settings. Pyrethroid resistance is widespread in these vectors, but limited data exist from the Southwest Pacific Region, especially from Melanesia. While Aedes vector ecology is well documented in Australia, where incursion of Ae. albopictus and pyrethroid resistance have so far been prevented, almost nothing is known about Aedes populations in neighbouring Papua New Guinea (PNG). With pyrethroid resistance documented in parts of Indonesia but not in Australia, it is important to determine the distribution of susceptible and resistant Aedes populations in this region.

METHODS

The present study was aimed at assessing Aedes populations for insecticide resistance in Madang and Port Moresby, located on the north and south coasts of PNG, respectively. Mosquitoes were collected using ovitraps and reared in an insectary. Standard WHO bioassays using insecticide-treated filter papers were conducted on a total of 253 Ae. aegypti and 768 Ae. albopictus adult mosquitoes. Subsets of samples from both species (55 Ae. aegypti and 48 Ae. albopictus) were screened for knockdown resistance mutations in the voltage-sensitive sodium channel (Vssc) gene, the target site of pyrethroid insecticides.

RESULTS

High levels of resistance against pyrethroids were identified in Ae. aegypti from Madang and Port Moresby. Aedes albopictus exhibited susceptibility to pyrethroids, but moderate levels of resistance to DDT. Mutations associated with pyrethroid resistance were detected in all Ae. aegypti samples screened. Some genotypes found in the present study had been observed previously in Indonesia. No Vssc mutations associated with pyrethroid resistance were found in the Ae. albopictus samples.

CONCLUSIONS

To our knowledge, this is the first report of pyrethroid resistance in Ae. aegypti mosquitoes in PNG. Interestingly, usage of insecticides in PNG is low, apart from long-lasting insecticidal nets distributed for malaria control. Further investigations on how these resistant Ae. aegypti mosquito populations arose in PNG and how they are being sustained are warranted.

Associations of Socioeconomic Status with Diet and Physical Activity in Migrant Bougainvilleans in Port Moresby, Papua New Guinea

Urban migrants in Papua New Guinea have undergone a nutritional transition. The present study investigated associations of socioeconomic status with dietary and physical activity patterns among migrant Bougainvilleans from Nassioi territory in the capital city of Port Moresby, Papua New Guinea. All adults Naasioi migrants residing in Port Moresby were identified (N = 185) and 70 were included. The International Physical Activity Questionnaire was used to evaluate physical activity, and dietary patterns were assessed by per-week consumption frequency of food items. Principal component analysis was applied to produce a composite score for socioeconomic status. Least square regression analysis indicated that socioeconomic status was positively correlated with consumption of a traditional diet (p = .03) and negatively with walking-related physical activity (p = .02), but it was not correlated with MET-minutes of moderate/vigorous activity. Different patterns of nutritional transition occur among migrants in urban Papua New Guinea, depending on socioeconomic status.