Powders from five elite plant materials (nutmeg, Myristica fragrans; red hot chilli pepper, Capsicum annuum; ginger rhizome, Zingiber officinale; black pepper, Piper nigrum and alligator pepper, Aframomum melegueta) at 1.5 % w/w concentration were assessed against cowpea bruchid, Callosobruchus maculatus infestations on stored cowpea seeds under laboratory environmental conditions in three agro-ecological zones in Nigeria by members of the Research Group. The conventional synthetic insecticide, permethrin was included as standard check, while untreated seeds served as the control. Adult mortality, oviposition rate and adult emergence were the indices considered in the experiments. For the first three days of exposure, black pepper (P. nigrum) powder caused the highest percentage mortality (68.8, 78.0 and 83.8 % respectively) of the bruchid adults and differed significantly (P < 0.01) from the rest of other treatments with the exception of permethrin that caused 78.8, 85.0 and 91.3 % mortality respectively. Similarly, black pepper powder and permethrin treatments differed significantly (P < 0.01) from the rest on number of eggs laid and emerged adults with the exception of Z. officinale rhizome, which did not differ significantly from P. nigrum on number of eggs laid. The results therefore suggest that black pepper powder has higher insecticidal potential over other plant materials and could serve as a biotechnological substitute to the synthetic insecticides in the control of C. maculatus infestations and damage in stored products.Contribution/Originality: The paper's primary contribution is finding that some bioinsecticides derived from medicinal plant materials could serve as substitute to the hazardous synthetic insecticides at economically justified concentration in the control of C. maculatus infestation and damage in stored cowpea seeds. INTRODUCTIONCowpea, Vigna unguiculuta (L. Walp) is an important food crop in tropical countries particularly in West Africa (Adedire and Ajayi, 2003). It has been reported that the crop is also a source of livestock feed and revenue in the

The insecticidal activities, toxic and histopathological effects of clove, Syzygium aromaticum L. were studied. Adult male albino rats weighing 150-60 g maintained in standard cages with free access to food and water were used for this experiment in year 2020. The plant powder was cold macerated in methanol to produce filtrate reconstituted for determination of median lethal dose (LD50) using Bruce's revised up and down procedure. Other assays followed standard methods too. The results showed that the botanical material, host resistance and permethrin are effective in controlling the maize weevil pest, Sitophilus zeamais Motschulsky infesting stored maize grains. Varietal resistance had no effect on the mortality of S. zeamais adults caused by S. aromaticum botanical insecticide at short storage period. Dry flower bud powder of clove, permethrin standard insecticide and resistance status had no effect on seed viability of maize grains when planted. The LD50 for S. aromaticum flower bud powder extract was 3000 mg kg -1 and this caused chills, convulsion and eventual death of the rats. The lowest weight gain in group IV rats administered 75% of the powder (2250 mg kg -1 ) in diet was an index of high powder concentration. The study revealed that 25 (750 mg kg -1 ) and 50% (1500 mg kg -1) supplementation of S. aromaticum did not adversely affect the serum biochemical indices, liver and kidney of the albino rats. The 75% S. aromaticum supplementation caused physiological damage in the animals. Therefore, supplementation of < 75% is recommended in the safe use of the botanical insecticide in pest control and herbal therapy.

Investigations on the alteration of tissues of two varieties of sweet potato (TIS 8700878 and TIS 8600356), incited byCurvularia lunata was carried out. Inoculated and uninoculated head, middle, and tail regions of sweet potato were treated, sectioned weekly for five weeks and photomicrographs taken. The plates revealed massive cell wall macerations and depletion of starch grains in the three regions of sweet potato assessed. Less damage was evident in the head region especially after one week of infection when compared with the middle and tail regions. There was general progressive tissue destruction and starch grains depletion from one to five weeks after inoculation with the pathogen. Appreciable tissue maceration was evident from the photomicrograph sections, particularly in the tail regions where there was total tissue breakdown and collapse of cell wall boundaries.

Experiment was conducted using near isogenic lines of Mercia background in a controlled environment to evaluate the mean effect of timing of inoculation and subsequent increase in temperature on deoxynivalenol (DON) concentration, amount of DON per grain and grain weight. The experiment was completely randomised consisting of three genotypes differing in semi-dwarfing alleles; Mercia 0 {Rht-B1a + Rht-D1a (wild type)}, Mercia 1 (Rht-B1b) and Mercia 2 (Rht-D1b) and four inoculation timings. The experiment was a complete factorial combination with four randomised replicates. Data showed that genotype differed in DON concentration (P<0.001), DON per grain (P=0.006) and mean grain weight (P=0.001) while time of inoculation influenced mean grain weight (P<0.001) and DON Concentration (P<0.001) but not Don per grain (P=0.23). Temperature influenced mean grain weight (P=0.002) with high temperature adversely affecting the size of the wheat grains.