I. N. EGBON

The use of pest control techniques in Agriculture have proven to be highly effective in addressing food insecurity and agricultural production issues. This study was conducted to compare growth and evaluate the yield of sweet potato under three different pest control techniques in relation to exposure to insect herbivory.These pest control techniques include physical exclusion, chemical exclusion and those without exclusion (no control). Sweet potato plants excluded physically were completely screened from herbivory using a net house, those excluded chemically were sprayed weekly with 0.01% Lambda-cyhalothrin and those without exclusion were fully exposed to herbivory. Stem length, number of leaves, number of runners, percentage herbivory and number of damaged leaves were parameters used to compare growth while tuber count, heaviest tuber and average tuber weight were used to evaluate yield. Sweet potatoes physically excluded significantly (p < 0.05) gave highest growth rates and this was evidently seen in their stem length, number of leaves and runners. Plants subjected to chemical exclusion and those without exclusion statistically had higher mean values in terms of yield than those physically excluded. However, the difference in yield from the three treatments did not vary significantly (p > 0.05) in tuber count (H2 = 2.34, p > 0.05), heaviest tuber (F2 = 1.67, p > 0.05) and average tuber weight (H2 = 4.24, p > 0.05). Sweet potatoes allocate more resources on growth when completely screened off from insect herbivory as seen by those physically excluded but this is was not enough to warrant improved yield.

In this study, the concentration dependent ovicidal effects of three botanicals were investigated on the eggs of Ephestia cautella. Three plants were selected for the experimental process, these include bitter leaf (Vernonia amygdalina), Neem leaf (Azadirachta indica) and Siam weed (Chromolaena odorata). Aqueous, alcohol and acetone extracts of the selected botanicals were prepared. Eggs of the insect Ephestia cautella were also collected and treated with the various extracts. The ovicidal activity of the various extract o the eggs of E. cautella was investigated after 96h and the percentage mortalities were estimated for the various extracts. Findings from the study revealed that for aqueous extract treatments, the highest percentage mortality 55.81% was recorded for treatments with aqueous extract of Siam weed while the lowest percentage mortality 6.97% was recorded for treatments with aqueous extract of Bitter leaf. For alcohol extracts treatments, the highest percentage mortality 20.00% was recorded for treatments with alcohol extract of Bitter leaf while the lowest percentage mortality 8% was recorded for treatments with alcohol extract of Neem leaf. Ovicidal effect of acetone extract on eggs of Ephestia cautella revealed that the highest percentage mortality 20.00% was recorded for treatments with acetone extract of Bitter leaf and Neem leaf. Aqueous extract of the botanicals were most effective in inhibiting the egg development of E. cautella. The study proved the efficacy of botanicals in preventing the growth and development of destructive plant pests such as Ephestia cautella. key words