Laboratory bioassays test of impregnated mosquito bed net fabrics with MOSKITUL^®LD1 netting fabrics

Final Report

1． Test material：

1.1 Mosquitoes:

species: Aedes albopictus mosquitoes from Guangdong Entomological Institute，reared in laboratory

1.2 Material：

1.2.1 Mosquito bed net: MOSKITUL^®LD1 mosquito bed net, 100% polyester netting impregnated with insecticide Crackdown^® (Insecticide: Deltamethrin 55mg/m²)(Hebei Shenglun I/E Corp., Ltd, Hebei, China.)

1.2.2 Insecticide Crackdown^®: Deltamethrin 2.5%SC(BAYER)

2．Test method：

2.1 Sample treatment and Bioassays test.

2.1.1 Washing method：

Basis for WHO/CDS/WHOPES/GCDPP/2005.11 WHO washing procedure:

Netting samples are individually introduced into beakers containing 0.5 l de-ionized water with 2 g/l soap (pH 10–11) added just before and fully dissolved. The beakers are immediately introduced into a water bath at 30°C and shaken for 10 minutes at 155 movements per minute. The samples are then removed and rinsed twice for 10 minutes in clean de-ionized water in the same shaking conditions as stated above. Nets are dried at room temperature and stored at 30°C in the dark between washes.

2.1.2 Bioassays test of KD (60min) and Mortality (24h)

Five susceptible, non-blood fed, 2–5-day old Aedes albopictus mosquitoes are exposed to each netting material under a transparent and ventilate glass cone for 3min. Then they are held for 24 hours with access to sugar solution. The netting material (25 cm x 25 cm) has been washed 20 times for 3 minutes and dried between the washes. The KD is measured after 60 minutes post exposure and mortality after 24 hours. 50 mosquitoes on each net (10 replicates) and samples of four different nets. Results were reported for each net tested along with the pooled results (5 × 10 × 4 = 200 mosquitoes). Mosquitoes exposed to untreated nets are used as controls. Bioassays were carried out at 25 ± 2 °C and 75 ± 10% RH.

2.2 The formula of KD and Mortality:

KD (Mortality)% = KD (dead) mosquitoes/test mosquitoes × 100

3．Result and Analyze

3.1 Knock Down rate ：

The KD rate after 60 minutes is an evaluation of the KD effect of the netting after 20 washes. The result is shown in Table I. The KD rate is 82% to Aedes albopictus with the netting fabric.

3.2 Mortality:

The Mortality after 24h is an evaluation of the effect of the netting after 20 washes. The result is shown in Table I. The Mortality is 80% to Aedes albopictus with the netting fabric.

Table I. Bioassays effect of KD and Mortality with MOSKITUL^®LD1 bed net fabric washed 20 times according to WHO washing procedure.

_2007.5

Treatment Item	Mosquitoes	KD （60min）	KD rates（%）	Death （24h）	Mortality （%）
Mosquito net fabric（1）	50	39	78	39	78
Mosquito net fabric（2）	50	42	84	41	82
Mosquito net fabric（3）	50	38	76	38	76
Mosquito net fabric（4）	50	45	90	42	84
Average	50	41	82	40	80

Note: * Laboratory bioassays was carried out at 25± 2 °C and 75 ± 10% RH.

**Effect result is the average of four test from same mosquito net fabric.

*** mosquito species: Aedes albopictus

3.3 Conclusion

The result is shown the 82% Knock Down effect after 60min and 80% Mortality after 24 hours to Aedes albopictus.

The tested samples of MOSKITUL^®LD1 netting fabrics have been shown a good efficacies in mortality rate to Aedes albopictus after washing 20 times, and the mortality is 80% after 24 hour.

GUANGDONG ENTOMOLOGICAL INSTITUTE

2007/05/30