Dynamics of malaria vector indices in two vegetation zones within North Eastern Adamawa State, Nigeria.

Studies profiling community and zonal malaria entomological risk indices are required to identify high risk areas where targeted control resources are most needed or likely to have the greatest impact on reducing risk of malaria infection. This study presents a first report on malaria vector risk indices in two vegetation zones within Adamawa state, Nigeria. Endophilic mosquitoes were collected for one year in selected communities in the Guinea and Sudan savanna zones within the State. Plasmodium falciparum Sporozoite and human blood meal ELISA assays were carried out on the female Anopheles mosquitoes collected. Sibling species composition of the An. gambiae complex were determined using PCR assays. Mean numbers of mosquitoes in the Guinea savanna communities were significantly (t = 7.73, DF = 11, p < 0.001) higher than the Sudan. Man-biting rates (F = 2.76, p = 0.13) of Anopheles mosquitoes were higher in the Guinea but not significantly different from Sudan savanna. Sporozoite rates of mosquitoes within the Guinea savanna were 2.7 times higher than the Sudan. The predominant Anopheles coluzzii species encountered in the state had higher overall human blood indices (0.63) and sporozoite rates (6.9%) compared to An. gambiae (0.39, 1.9%) and An. arabiensis (0.58, 2.3%) respectively. Overall annual human blood indices (0.59) of mosquitoes in Adamawa were lower compared to reports from other States. Prevalence and higher transmission risks indices of endophilic An. coluzzii mosquitoes reveal the need for LLIN and management of relatively permanent An. coluzzii breeding sites in the State. Widespread cattle rearing lifestyle and lower human blood indices of mosquitoes in the study area suggest the need to investigate cattle blood indices of the mosquitoes in the state. Higher entomological risk indices in the Guinea Savanna zone provide baseline information for prioritization of malaria vector control supplies within the State.

Dynamics of malaria vector indices in two vegetation zones within North Eastern Adamawa State, Nigeria

@#Studies profiling community and zonal malaria entomological risk indices are required to identify high risk areas where targeted control resources are most needed or likely to have the greatest impact on reducing risk of malaria infection. This study presents a first report on malaria vector risk indices in two vegetation zones within Adamawa state, Nigeria. Endophilic mosquitoes were collected for one year in selected communities in the Guinea and Sudan savanna zones within the State. Plasmodium falciparum Sporozoite and human blood meal ELISA assays were carried out on the female Anopheles mosquitoes collected. Sibling species composition of the An. gambiae complex were determined using PCR assays. Mean numbers of mosquitoes in the Guinea savanna communities were significantly (t = 7.73, DF = 11, p < 0.001) higher than the Sudan. Man-biting rates (F = 2.76, p = 0.13) of Anopheles mosquitoes were higher in the Guinea but not significantly different from Sudan savanna. Sporozoite rates of mosquitoes within the Guinea savanna were 2.7 times higher than the Sudan. The predominant Anopheles coluzzii species encountered in the state had higher overall human blood indices (0.63) and sporozoite rates (6.9%) compared to An. gambiae (0.39, 1.9%) and An. arabiensis (0.58, 2.3%) respectively. Overall annual human blood indices (0.59) of mosquitoes in Adamawa were lower compared to reports from other States. Prevalence and higher transmission risks indices of endophilic An. coluzzii mosquitoes reveal the need for LLIN and management of relatively permanent An. coluzzii breeding sites in the State. Widespread cattle rearing lifestyle and lower human blood indices of mosquitoes in the study area suggest the need to investigate cattle blood indices of the mosquitoes in the state. Higher entomological risk indices in the Guinea Savanna zone provide baseline information for prioritization of malaria vector control supplies within the State.

Influence of gamma irradiation on productivity indices of the edible Emperor moth caterpillar, Cirina forda (Lepidoptera: Saturniidae).

This study was aimed at generating baseline information for sustainable genetic improvement of Cirana forda larvae for entomophagy, through the use of gamma irradiation. Eggs of C. forda were irradiated with increasing doses of gamma rays from 0 to 200 Gy and raised through larval instal stages under laboratory conditions. The Body Weight (BW) and Head Capsule Width (HCW) of the larval instar stages were monitored as indices of productivity. Successful larval emergence was recorded for all irradiation doses tested and BW of the 1st and 2nd instar larvae were not significantly (p > 0.05) different between the control and treated groups (range = 0.021 +/- 0.003 g/larva in the 200 Gy treatment to 0.028 +/- 0.003 g/larva in the control group and 0.105 +/- 0.003 g/larva in 20 Gy treatment to 0.172 +/- 0.009 g/larva in the control group, respectively). On the other hand, BW during the 3rd and 4th larval instars were significantly (p < 0.05) lower among the irradiated treatments than control. Pattern of distribution of HCW was different from that of BW; as HCW increased with irradiation dose from 10-50 Gy during the 3rd and 4th larval instars. Also, HCW during the 5th instar larvae among the irradiated treatments (range = 5.256 +/- 0.012 to 5.662 +/- 0.026 mm) were not higher than that of the 6th instar in the control group (6.065 +/- 0.010 mm). These results suggest promising potentials of the use of gamma irradiation in sustainably improving the productivity of C. forda larvae for entomophagy.

Seasonal trends in epidemiological and entomological profiles of malaria transmission in North Central Nigeria.

The influence of seasonal changes on epidemiological and entomological indices of malaria transmission in North Central Nigeria was elucidated in a series of studies carried out between January 2004 and December 2009. The climate in the study area was divided into three seasonal periods namely, rainy (May-October), dry (December-March) and transitional (April and November), during which larval and adult anopheline mosquito collections were carried out and assessed for densities, sporozoite infection and parity rates and potentials for malaria transmission. The results indicated that the climate in the study area was clearly seasonal, with close similarities in the patterns of distribution of the climatic factors in the study sites. Mosquito densities, both at the adult and larval stages (i.e., 29.35 +/- 5.10 adult mosquitoes/man/night and 10.36 +/- 3.34 larvae/dip, respectively), were significantly (p<0.05) highest during the rainy season. However, while the former varied significantly in the three seasonal periods, the latter was not significantly different during the dry and transitional seasons. Malaria transmission risks, in terms of sporozoite rates and entomological inoculation rates, was significantly (p<0.05) least in the dry season (i.e., 2.89 +/- 1.25% and 0.37 +/- 0.21 infective bite/man/night, respectively) but the two variables were not significantly (p>0.05) different during the transitional and rainy seasons. Adult mosquito daily survival rate and adult longevity were least in the dry season (26.52 +/- 11.80% and 6.80 days, respectively) and significantly (p<0.05) highest during the rainy season (72.28 +/- 4.00% and 16.95 +/- 4.20 days, respectively). Parous rates of the mosquitoes and duration of sporogony had distinct distribution pattern from the other variables investigated. While, significantly highest parous rates were recorded in the transitional season (86.00 +/- 4.30%), duration of sporogony was not significantly (p>0.05) different during the three seasons. The epidemiology of urban malaria in North Central Nigeria was discussed from the view points of the these results and concluded that the findings should promote the development of informed temporally-targeted vector control programs for the area.