Maize is cultivated worldwide and used as food and for fuel production. It is usually attacked and destroyed during storage by Sitophilus zeamais. With inaccessibility to synthetic pesticides, farmers are left with the choice of using locally available plant based pesticides. For this reason, we tested the insecticidal potentials of essential oils (EOs) of Chenopodium ambrosioides and Cupressus sempervirens and their binary combinations against S. zeamais on stored maize. Mortality, progeny inhibition, repellence and damage were tested. Pesticide characteristics of both essential oils were dose-dependent, 200 μL/kg of all the combinations caused at least 80% mortality within 14 days of storage while the 50:50 combination completely inhibited progeny production. Moreover, 8 μL of all the EO were repellent to the weevils. The 50:50 binary combination was the most active in all the tests carried out. Pesticidal interactions between the oils in combination were mostly additive and synergistic. There was also a good control of insect population increase and grain damage after six months of storage. Therefore both EOs can be recommended for the control of S. zeamais.

The response of pests to the effects of a botanical insecticide can vary spatially and temporally. To test whether efficacy of botanicals differed spatially, the insecticidal efficacy of Gnidia kaussiana and Ocimum canum against Callosobruchus maculatus was investigated in two different agro-ecological zones of Cameroon, i.e. Maroua and Ngaoundéré (sudano-sahelian and sudano-guinean zones, respectively). Experiments were, therefore, conducted to determine the insect mortality, progeny production, grain damage and weight loss in cowpea. G. kaussiana was more effective against C. maculatus in Maroua (LD50 = 0.12 g/kg at 6th day of exposure) than in Ngaoundéré (LD50 = 4.35 g/kg at 6th day of exposure). Moreover, it was more toxic than O. canum extract and neem seed oil (reference), irrespective to the agro-ecological zones. Overall, the performance of O. canum did not vary significantly between the two zones, and was slightly more active (LD50 = 4.66 g/kg) than the reference insecticide neem seed oil (LD50 = 4.89 g/kg) in Ngaoundéré in contrast to the results recoded in Maroua (LD50 = 1.44 g/kg and 2.60 g/kg, respectively for neem seed oil and O. canum at 6 days post exposure). In view of the above, there were some discrepancies in extract performance between Maroua and Ngaoundéré. Thus, the establishment of dose rates of insecticidal products formulated from G. kaussiana must be specific to an environment in contrast to those from O. canum.

Laboratory tests were conducted in order to assess the potential insecticidal effect of hexane, acetone and methanol fractionated extracts from Hemizygia welwitschii leaves against Sitophilus zeamais Motschulsky, important stored maize pest. The three extracts used individually were applied at four different concentrations (2, 4, 6 and 10 g/kg of maize) against the weevil. The efficacy of the treatment was evaluated by recording adult mortality after 1, 3, 7 and 14 days of infestation, and the F1 progeny emergence. Population increase, grain damage, and seeds germination were also assessed after three months of storage. The results showed that, among the three fractionated extracts, hexane extract was the most effective with 100% mortality recorded within 14 days after infestation at the concentration of 10 g/kg of maize, followed by acetone extract with 83.75% and methanol extract with 79.21% of mortality. The LC50 values decrease with the increase of exposure periods. The 14-day LC50 values were 0.78 g/kg, 1.58 g/kg and 3.10 g/kg respectively for hexane, acetone and methanol extract. The three extracts achieved significant inhibition of F1 progeny at all the concentrations. Among them, the hexane and methanol extracts induced complete inhibition of F1 progeny emergence at 10 g/kg of maize, acetone extract recorded 82.33% of inhibition. Significant reductions of insect population growth and percentage of seed damage were recorded after three months of storage on the maize treated with each extract at all the concentrations compared to negative control. Furthermore, no alive insects was recorded in maize seeds treated with the three extracts at the concentration of 10 g/kg. It is noticed that, percentage of gain damage were similar (0.15%) in maize treated with hexane and methanol extracts at 10 g/kg, while acetone extract recorded 0.76% of grain damage. In general, these extracts had no negative effect on the germination capacity of maize grains at the end of storage. Overall, the results obtained indicate that the use of these fractionated extracts could serve as an alternative to synthetic insecticides.

Bafanji village harbors a plethora of plants used in the treatment of several ailments. Alarmingly, traditional knowledge is quickly declining due to inadequate documentation and limited cross-generational transfer of knowledge. In this study indigenous medicinal plans were documented for their use, management and the threats affecting them. The study was carried out in Bafanji village between August 2015 and March 2016. Semi-structured questionnaires, interviews and field trips were used for data collection. Sample specimens were collected and identified. This study revealed that 6.06% of the population relied solely on medicinal plants for their health care while 15.14% do not use medicinal plants directly and 78.8% rely on both modern and traditional medicine for the treatment of their ailments. 92 plant species belonging to 51 families and 83 genera were documented. Family Asteraceae was the most represented (14.1%). More than one plant species is used to treat various ailments with the highest number of species (19) for malaria. Among the medicinal plant species recorded from the study area, the majority (55.4%) which were mainly herbs (70.7%) were collected from the wild. The leaves were the most commonly used plant part (44.5%). The principal method of remedy preparation was reported to be decoction. Oral administration was the most preferred mode. Knowledge of the use of plants as medicines was found to be confined to traditional healers and older folk. Documenting the eroding indigenous knowledge of medicinal plants and spurring youths to acquire traditional medicinal knowledge is recommended.

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