Studies on aspects of the bionomics and pest status of Piezotrachelus varius Wagner (Coleoptera: curculionidae) on cowpea (Vigna unguiculata (L) walp in the western derived savanna zone of Cameroon

Studies were conducted on the population fluctuations of the cowpea pod weevil, Piezotrachelus varius on cowpea at Melong, NY(lkon and Babessi, and the susceptibility of seeds of selected cowpea cultivars to its damage in the western derived savanna zone of Cameroon, during the 1999 and 2000 cowpea cropping seasons. Results showed that 1-2 P. varius adults/plant were found on cowpea plants during the pret10wering stage but increased at flowering and pod filling stages to a peak of 11 adults/plant at pod maturity. In the laboratory, adults continued to emerge daily within two weeks of storage of harvested pods. There were no significant differences in the duration of P. varius development on the different cowpea varieties tested. The developmental period from egg to pupation and mean pupal duration ranged from 10.4-11.1 days and 6.3-6.7 days, respectively. The total developmental period (egg - adult) on all tested cowpea varieties ranged from 16.6-17.7 days. Field evaluations of the damage to cowpea seeds by P. varius, showed that all cultivars screened were susceptible; the degree of seed damage varied with cowpea cultivars. The overall seed damage by P. varius at Melong was =50%, on Melong local, Foumbot local, IT90k-59, TVu13740 and IT87D-1676 cowpea cultivar while that on TVu3236, MTA 22 and Babessi local was 12% damage. The number of P. varius that emerged from infested pods of the different cowpea cultivars in storage, was positively co-related with the percentage of damaged seeds

Traditional use of indigenous mosquito-repellents to protect humans against mosquitoes and other insect bites in a rural community of Cameroon

Objective: To document and test the efficacy of indigenous traditional personal protection methods against mosquito bites and general nuisance.Design: A prospective study based on a survey and field evaluation of selected plant-based personal protection methods against mosquito bites.Setting: Bolifamba, a rural setting of the Mount Cameroon region.Subjects: A structured questionnaire was administered to 179 respondents and two anti-mosquito measures were tested under field conditions.Main Outcome Measures: Identified traditional anti-mosquito methods used by indigenes of Bolifamba. Two plants tested under field conditions were found to be effective.Results: Of the 179 respondents, 88 (49. 16%) used traditional anti-mosquito methods; 57 (64.77%) used plant-based methods while 31 (35.2%) used various petroleum oils. The rest of the respondents, 91 (50.8%) used conventional personal protection methods. Reasons for using traditional methods were because they were available, affordable and lack of known more effective alternatives. The demerits of these methods were: labourious to implement, stain dresses, produce a lot of smoke/repulsive odours when used; those of conventional methods were lack of adequate information about them, high cost and non-availability. When the two most frequently used plants, Saccharum officinarium and Ocimum basilicum were evaluated under field conditions, each gave a better protection than the control.Conclusion: Most plants used against mosquitoes in the area are known potent mosquito repellents but others identified in the study warrant further research. The two tested under field conditions were effective though less than the commonly used commercial diethyltoluamide

Arbuscular-mycorrhizal fungi, rhizobia and Metarhizium anisopliae enhance P, N, Mg, K and Ca accumulatons in fields grown cowpea

The concentrations ofP, N, K, Mg, Cain cowpea (Vigna unguiculata (L.) Walp.) roots and shoots were assessed at 45 Days After Planting (DAP) in inoculated and uninoculated plants at sowing with rhizobia and Arbuscular-Mycorrhizal Fungi (AMF). Those of harvested seeds from inoculated and uninoculated plants at sowing or sprayed and unsprayed plants at flowering with Metarhizium anisopliae were also assessed. Field trials were carried out in a complete Randomized Block Design with four treatments, in the Sudano-Sahelian (zone I), Guinea-Savannah (zone II), monomodal and bimodal hlllIlid-forest rainfall (zone IV and V) of Cameroon. The contributions of rhizobia and AMF to cowpea shoots and roots nutrients uptake at 45 DAP significantly accOlmted for up to 17% for total N, 52% for available P, 19% for Ca, 55% for Mg, 46% for K. Compared to the control, AMF+rhizobia, M. anisopliae, AMF+rhizobia and M. anisopliae significantly increased (p ~ 0.04) the N, P, Ca, Mg and K seed concentrations in zone-I (2000 and 2001), zone-II (1999), zone-IV (2004) and zone-V (1999 and 2001) at harvest. The two symbionts and M. anisopliae almost had the same influence on plant nutrient uptake within agro ecological zones. These results demonstrate the dependency of cowpea on microbial inoculants for nutrient acclUllulations in cowpea plants. However, more work still need to be camed out to investigate on the mechanisms by which M. anisopliae contributes to the increment of nutrient uptake in harvested cowpea seeds

Contribution of Arbuscular mycorrhizal fungi (AMF), rhizobia and metarhizium anisopliae to cowpea production in Cameroon

The objective of this study was to investigate on how the interactions between the microbial syrnbionts (AMF+rhizobia) and the rnycopesticide M. anisopliae can affect the cowpea production in varied agro ecological zones of Cameroon. Cowpea of the Bafia local cultivar was grown from 1999 to 2004 in the Sudano-sahelian (zone-I), Guineasavannah (zone-II), monomodal (zone-IV) and bimodal humid-forest rainfall (zone-V) of Cameroon. Two cropping seasons were experimented in each zone, but in different years except in zone-IV. Experiments were conducted in a Randomised Block Design (RED) with two levels of inoculation at sowing (uninoculanted seeds and dually inoculated seeds with Arbuscular Mycorrhizal Fungi (AMF) and rhizobia and two levels of spray applications at onset of flowering with the mycopesticide (Metarhizium anisopliae), or the insecticide Deltamethrin ®. Results indicate that inoculation significantly increased cowpea biomass in the first and second cropping years, respectively by 38 and 40% in zone-I, 54 and 43% in zone-II, 55 and 46% in zone-IV, 41 and 51 % in zone-Vat 45 Days After Planting (DAP). Inoculated plants showed a low but significant (p = 0.01) response to AMF colonization in all the trials compared to uninoculated plants. Nodules were formed by native and introduced rhizobia while the number and dry weight of nodules were significantly higher (p<0.0 1) in roots of inoculated than those of uninoculated plants. Inoculated and sprayed treatments significantly produced more pods per plant (p<0.01) and enhanced the dry weight of pods per plant at harvest (p = 0.03) in all trials compared to the control. These results suggest that AMF, rhizobia and M. anisopliae are variously efficient microsyrnbionts and mycopesticides in different Cameroonian soils and may be used as economical and safe bio-inoculants to improve cowpea production in the country

Management of cowpea flower thrips, Megalurothrips sjostedti (Thysanoptera, thripidae), in Cameroon

A series of experiments were conducted in Cameroon to investigate options for managing cowpea flower thrips, Megalurothrips sjostedti, via arbuscular mycorrhiza fungi, rhizobia and Metarhizium anisopliae. Six cowpea fields were established in three agroecological zones over a 3-year period. The abundance of both larvae and adults of M. sjostedti was assessed on plants grown from (1) seeds co-inoculated at sowing with arbuscular mycorrhiza fungi (AMF) and rhizobia (mycorrhiza/rhizobia); (2) non-inoculated seeds and plants sprayed three times with M. anisopliae (Metarhizium); (3) seeds co-inoculated at sowing with AMF and rhizobia and plants sprayed three times with M. anisopliae (mycorrhiza/rhizobia/Metarhizium); (4) non-inoculated seeds and plants sprayed three times with the synthetic insecticide deltamethrin; and compared with (5) a control consisting of non-inoculated seeds and unsprayed plants. Results indicate that thrips infestation was associated with the flowering cycle and was higher in the first than in the second cropping season in most agroecological zones. In general, M. sjostedti larval and adult counts were significantly higher (Po0.01) in the control than in other treatments. Compared with the control, treatment insecticide obtained the highest reduction of adults (range 52–95%) and larvae thrips population (64–97%), followed by mycorrhiza/rhizobia/Metarhizium (29–56%) and (29–49%), mycorrhiza/rhizobia (31–49%) and (24–52%), and Metarhizium (25–58%) and (5–52%), respectively. In all of the above treatments, the reduction of thrips led to a subsequent increase of seed yield, although it was not always significant. Apart from two cases (Ngaounde´re´ 2000 and Nkolbisson 1999), biological treatments (Metarhizium, mycorrhiza/rhizobia and mycorrhiza/rhizobia/Metarhizium) consistently reduced grain yield loss in the trials compared with the control at Ngaounde´re´ in 1999 and Maroua 2001. These results are discussed in the context of sustainable management of M. sjostedti populations on cowpea. r 2007 Elsevier Ltd. All rights reserved