Insectifugal and insecticidal potentials of two tropical botanical essential oils against cowpea seed bruchid

Essential oils (EO) obtained from Xylopia parviflora root bark and Hoslundia opposita leaf via hydro distillation were analysed by GC-MS and evaluated for their insectifugal (repellent) and insecticidal activities against cowpea seed bruchid (Callosbruchus maculatus Fabricius), a cosmopolitan pest of cowpea seeds. X. parviflora was predominated by sesquiterpenes (59.57%), with the main compounds being β-himachalene (22.68%), 1,7,7,Trimethylbicyclo[2.2.1]hept-5-en-2-ol (19.68%), β-elemene (14.41%), 5(1H)-Azulenone, 2,4,6,7,8,8a-hexahydro-3,8-dimethyl-4-(1-methylethylidene)-(85-cis)- (12.38%) and (-)-α-parasinsen (8.34%). The predominant compounds in H. opposita EO were 1,8-cineole (61.15%), followed by α-terpineol (16.81%) and β-phellandrene (13.25%). Percentage repellence at application rates of 0.66-1.32 μl/cm² (46.93-73.07%) was significantly (p < 0.05) higher than that of control (17.73%). RD₅₀ (repellence dose for 50% of treated adults) for H. opposita (0.43 μl/cm²) was not significantly different from the value for X. parviflora (0.60 μl/cm²). Although higher percentage of male mortality than female mortality was observed due to topical application of the EOs, the disparity was not significant. The results of correlation of the chemical groups of the EOs with the insectifugal activity indicate that the observed bioactivity was due to the synergistic effects of the chemical groups. The two EOs are therefore recommended for incorporation into bruchid protection schemes in the tropics.

Determination of Organochlorine Pesticide Residues in Dried Cocoa

Organochlorine pesticide residues in dried cocoa beans from selected towns from Ondo and Osun States, Nigeria were determined. Four towns Ondo and Idanre (Ondo State) and Ife and Ilesa (Osun State) were selected to represent cocoa producing areas in the states. Samples were extracted and cleaned-up on silica gel adsorbent. Pesticide residues were detected using Gas Chromatography – Mass Spectrometry (GC-MS). Five organochlorine pesticides were detected in the samples from Ondo state which includes alpha-HCH, beta-HCH, delta-HCH, endrin andp p’DDT. The levels ofp p’DDT (0.108 mg/kg and 0.107 mg/kg) detected in samples from Ondo and Idanre towns were lower than the EU MRL (0.5 mg/kg), while other detected organochlorine pesticide residues from the State were higher than the EU MRL. In Osun State, alpha-HCH, lindane, dieldrin, endrin, heptachlor-epoxide, endosulfan I andp p’DDT were organochlorine pesticide residues detected, with lindane (0.074 mg/kg), endosulfan I (0.099 mg/kg) andp p’DDT (0.235 mg/kg) being lower than EU MRLs. Higher levels of organochlorine pesticide residues than the EU MRLs suggest that the produce were not safe for human consumption because of the tendency of the pestsides to persist for a long period of time and as well bioaccumulate within the environment. The produce can also face trade threat in international market. Measures were suggested to ameliorate this situation.

Rural Farmers’ Perceptions, Knowledge and Management of Insect Pests of Fruit Vegetables in Ogbomoso Agricultural Zone of Nigeria

Surveys were carried out in five local government areas of Ogbomoso Agricultural Zone Nigeria during planting season in 2010 to investigate rural farmers perceptions and management practices of insect pests of fruit vegetables. The survey involved 150 randomly selected farmers who were interviewed using structured questionnaire. Fruit vegetables planted by the farmers were okra, tomatoes, pepper and garden egg. Reasons given by farmers for cultivating fruit vegetables were significantly favored by age category, educational qualification, and secondary occupation of farmers (x2 = 4.757, P = 0.029). Field insect pests were perceived as the major production constraint to fruit vegetables in this zone. Majority of the farmer estimated 78.4 % rated insect pest as the most serious pest infesting fruit vegetables, the insect pests were grasshopper (Orthoptera), beetles (Coleoptera) and caterpillar (Lepidoptera). Integrated pest management module consisted basically of chemical and cultural control strategies, with weeding, shifting cultivation and crop rotation as main cultural control methods. More than 76.7 % of the farmers make use of cultural control because of unavailability and cost of chemical insecticides. Only 23.3 % had access to chemical insecticides in controlling insect pest of fruit vegetables.

Rural Farmers’ Perceptions, Knowledge and Management of Insect Pests of Fruit Vegetables in Ogbomoso Agricultural Zone of Nigeria

Surveys were carried out in five local government areas of Ogbomoso Agricultural Zone Nigeria during planting season in 2010 to investigate rural farmers perceptions and management practices of insect pests of fruit vegetables. The survey involved 150 randomly selected farmers who were interviewed using structured questionnaire. Fruit vegetables planted by the farmers were okra, tomatoes, pepper and garden egg. Reasons given by farmers for cultivating fruit vegetables were significantly favored by age category, educational qualification, and secondary occupation of farmers (x2 = 4.757, P = 0.029). Field insect pests were perceived as the major production constraint to fruit vegetables in this zone. Majority of the farmer estimated 78.4 % rated insect pest as the most serious pest infesting fruit vegetables, the insect pests were grasshopper (Orthoptera), beetles (Coleoptera) and caterpillar (Lepidoptera). Integrated pest management module consisted basically of chemical and cultural control strategies, with weeding, shifting cultivation and crop rotation as main cultural control methods. More than 76.7 % of the farmers make use of cultural control because of unavailability and cost of chemical insecticides. Only 23.3 % had access to chemical insecticides in controlling insect pest of fruit vegetables.

Effects of harvesting methods on physicochemical and microbial qualities of honey

Honey harvesting is accomplished using two main methods: traditional and modern methods; the former involves the use of naked flames to rid off or even destroy honey bees, while the latter involves use of smoke to suppress bees' aggressiveness. This research work investigated the effect of the method of harvesting on the quality of honey. The quality attributes investigated include: colour, total solids, viscosity, pH, diastase activity, acidity, sugars, ash, nitrogen, total antioxidants, hydroxymethylfurfural (HMF) content and microbial properties. The results revealed that the honey samples harvested using modern harvesting method had better quality in terms of ash content, total antioxidants, diastase activity, colour, sugars and microbiological attributes. The lower quality of honey harvested using traditional method could be attributed to the adverse effect of the burning during traditional harvesting on the quality of the honey. It is therefore concluded that modern method of harvesting honey produces better quality of honey and should be encouraged.