Comparative assessment of the potency of two insecticidal plant (<i>Tithonia diversifolia</i> and <i>Jatropha curcas</i>) extracts against pink stem borer, <i>Sesamia calamistis</i> (Hampson)

Abstract

Maize (Zea mays ssp. mays) originated in Mexico and Central America and belongs to the tribe Maydae of the family  Poaceae. There are different varieties of this  wonderful crop, but with this comes difficulty in growing them due to  infections. Various means has been tried and adopted in getting rid of pests causing serious damage to maize planted  by farmers. One of such trials is the use of synthetic insecticides. An alternative way was discovered which is far less  harmful to both humans and animals, unlike the synthetic insecticides which are toxic to mammals and the ecosystem.  This study was carried out to determine the comparative assessment of the potency of two insecticidal plant extracts,  Tithonia diversifolia and Jatropha curcas against pink stem borer, Sesamia calamistis (Hampson). Maize variety, BR 9943  DMRSR (white) was planted and later infested with blackhead stage egg batches of Sesamia calamistis 3 weeks after  crop emergence. Twenty percent aqueous leaf extract of Tithonia diversifolia and 1mg/1ml ethanol seed oil extract of  Jatropha curcas were applied 1 week after arranged infestation. Carbofuran 3G (1g/plant) was used as a standard check  treatment and untreated plants were included as controls. Application of both plant extracts, markedly reduced stem  tunneling, stem breakage, deadheart formation, exit/entry holes and number of emerged larvae in treated plants. Plant  heights at 2 and 4 weeks after infestation were also maintained positively in treated plants. Jatropha curcas showed the  highest bioactivity potential in reducing Sesamia calamistis damage. The use of these plant extracts is very effective in  controlling infections in maize.