Evaluation of Eucalyptus tereticornis, Tagetes minuta and Carica papaya as stored maize grain protectants against Sitophilus zeamais (Motsch.) (Coleoptera: Curculionidae)

https://www.researchgate.net/publication/266910539,Sitophilus zeamais (Motsch.) is an important storage pest of maize grain in several parts of Africa including Zimbabwe. Although synthetic pesticides are effective at controlling the pest, environmental and health hazards of these chemicals are of increasing concern. The study assessed efficacy of botanical leaf powders of Eucalyptus tereticornis, Tagetes minuta and Carica papaya in controlling S. zeamais using rates of 5 g, 10 g and 20 g per 200 g of open pollinated maize grain (variety ZM421). The trial was laid in a completely randomised design (CRD), with 12 treatments replicated three times. The grain was put in a freezer at -4oC for a fortnight, before the botanicals were added, to kill any prior sources of weevil inoculum and eggs which might be already pre-existing in the grain. 200 g maize grain was infested with 200 three week old unsexed pure culture weevils in 750 ml jars. After 14, 28, 42, 56 and 70 days, weevils were sieved and their mortality determined. Percentage grain weight loss was assessed after 35 days post pests introduction. There were significant differences (p