Comparison of cone bioassay estimates at two laboratories with different Anopheles mosquitoes for quality assurance of pyrethroid insecticide-treated nets

Table 1 Summary of experiments conducted at Ifakara Health Institute (IHI) and Papua New Guinea Institute of Medical Research (PNGIMR)

Experiment	Bioassay test in IHI	Cone bioassay test in PNGIMR
Number of ITNs tested	20 nets (100 net pieces)	20 nets (100 net pieces)
Mosquitoes exposed	20 per net piece (cone bioassay) 100 per net piece (tunnel tests)	20 per net piece (cone bioassay)
Experiment conditions	27 ± 1 °C (cone bioassay) 55–82% RH (cone bioassay)	28 ± 4 °C (cone bioassay) 53–71% RH (cone bioassay)
	27ºC ± 2 ºC (tunnel tests) 60–100% RH (tunnel tests)
Mosquito species	Pyrethroid susceptible^* An. gambiae s.s	Pyrethroid susceptible^* An. farauti s.s
Mosquito age	3–5 days (cone bioassay) 5–8 days (tunnel tests)	2–5 days (cone bioassay)
WHO efficacy criteria	≥ 95%KD60 or ≥ 80% M24 (cone bioassay)	≥ 95% KD60 or ≥ 80% M24 (cone bioassay)
	≥ 90% BFI and/or ≥ 80% M24 (tunnel tests)

RH relative humidity, KD60 knockdown measured at 60 min (sublethal incapacitation), M24 mortality measured at 24 h post exposure, BFI blood feeding inhibition
^*Sugar fed Anopheles gambiae s.s (Ifakara) and Anopheles farauti s.s were confirmed to be 100% susceptible to alpha-cypermethrin, deltamethrin and permethrin insecticides at 1× WHO discriminating concentration at the time of evaluation

ISSN: 1475-2875