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<p>The use of chemical insecticides in crop production has resulted in increased food production in Africa, but their use has resulted in the destruction of beneficial organisms and development of resistance by some insects to the insecticides. The effectiveness of garlic <em>Allium sativum</em> and hot pepper, <em>Capsicum frutescens</em> in controlling the pests of cabbage, <em>Brassica oleracea</em> was evaluated. These botanicals were compared with a standard chemical insecticide Attack® (Emamectin benzoate). The experiment was conducted in a randomized complete block design, with 3 treatments and a control, each of which was replicated 3 times. <em>Plutella xylostella, Brevicoryne brassicae, Hellula undalis</em> and <em>Trichoplusia ni</em> were found on cabbage plants. Significantly fewer of them were found on the treated plants than the control plants. The use of the plant extracts resulted in a reduction in mortality ranging from 10.76% to 55.94%. Fewer natural enemies of <em>B. brassicae</em> were sampled on the insecticide-sprayed plots than the garlic and pepper-sprayed plots. The cost of protecting cabbage plants from insect infestation using Attack was higher than the botanicals. Garlic-treated plots recorded the highest cost: benefit ratio of 1:16 while Attack®-treated plots recorded the least of 1: 9.2. The control effects of the botanicals compared favourably with that of the chemical insecticides. Thus these botanicals can be used as substitutes to chemical insecticides.</p>

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A 2-year field experiment was conducted in 2012 and 2013 at the research fields of CSIR-Crops Research Institute to determine the best agronomic practices for the field establishment and cultivation of Chia (Salvia hispanica) and determine insect pests and diseases associated with the plant. The study also determined the nutritional composition of the plant under Ghanaian environment. A split-plot field trial with 2 planting methods (direct planting with seed; planting from seedling) as main plot and 3 planting density (10,000 plants/ha; 20,000 plantst/ha; 40,000 plantst/ha) as subplot were used for the agronomic evaluation of the plant. A sweep net was used to sweep diagonally across the field under two separate regimes to collect insects on the crop for the entomological investigations. Major insects collected were coreid bugs, lagria sp., Zonocerus variegatus and Diopsis thoracica. The method used for the pathological investigations were the moist blotter test and culture of pathogens on Potato Dextrose Agar. The results of the study in both years show high biomass and seed yield of chia when the crop was planted directly in the field. Narrow-row spacing of 0.5m x 0.5m consistently produced the highest biomass and seed yield in both years of the study. The results indicated that interaction between planting method and planting density positively influenced most of the growth and yield parameters of Chia plants. Nutritional profile analysis from the Chia seeds shows medium to high proximate and mineral composition. Disease evaluation revealed evidence of Fusarium wilt infection on Salvia hispanica in the field. The study recommends the adoption of direct planting method and narrow-row spacing (0.5m x 0.5m) (SP3) as the best option for the production of Chia plants in Ghana.

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The use of chemical insecticides in the control of insect pests has left in its wake resistance of some pests to some of the conventional insecticides. Alternative methods of managing pests such as cultural control have to be employed to reduce pest infestation of crops. Onion was used in an intercrop as a non host crop to manage the pests of cabbage. The experiment was conducted in a Randomized Complete Block Design with four treatments; sole cabbage (T1), 2 rows of cabbage to 1 row of onion (T2), 3 rows of cabbage to 1 row of onion (T3) and 4 rows of cabbage to 1 row of onion (T4), each of which was replicated three times. Data were collected on pests' numbers, plant height, damaged leaves at harvest, canopy spread, number of damaged heads and fresh weight. Significantly fewer Bemisia tabaci, Hellula undalis and Brevicoryne brassicae infested the intercropped plants than the sole crop. However, intercropping cabbage with onion did not significantly reduce Plutella xylostella population on cabbage. Number of damaged heads, fresh weight and damaged leaves were significantly different (P< 0.05).

Many braconid wasp species inject polydnaviruses to overcome their host's immune system. In the species Cotesia sesamiae, two biotypes exist that differ in their ability to develop in the host Busseola fusca. The biotype from coastal Kenya is infected with Wolbachia and is not able to develop in larvae of B. fusca, whereas the uninfected inland biotype of this wasp can develop in B. fusca. The genetic transmission of the developmental ability was studied through a series of genetic crosses and superparasitization experiments. The Wolbachia infection of the coastal type did not play a role in the encapsulation response of the host. Experiments show that the polydnaviruses of the wasps could not prevent the encapsulation of the coastal parasitoid eggs. Most likely, larval characteristics such as surface proteins played a more important role in the encapsulation response of the host even in the presence of a functional polydnavirus.

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