Original Articles
C. O. Okonkwo and O. C. Ohaeri
Abstract
The phytopesticidal effects of Piper guineense, Capsicum annum, Zingiber officinale and Lippia adoensis were tested for the mortality rates of the following insects: Rhaffella germanium, Aedes spp, Diphtheria spp and the brown plant hoppers. Percentage mortality rates of 89.5±2.2 for Rhaffella germanium; 55.3 ± 4.6 for Aedes spp; 92.4 ± 1.8 for Diphtheria spp and 61.7 ± 3.4 for the brown plant hopper was recorded by Piper guineense as compared to Capsicum annum which had mortality rates in percentage as 90.9 ± 3.2 for Diphtheria spp; and 50.5 ± 3.3 for the brown plant hopper.Lippia adoensis also had mortality rates in percentage of 56.3 ± 3.0 for Rhaffella germanium, 87.7 ± 2.7 for Aedes spp; 69.3 ± 5.9 for Diphtheria spp and 61.1 ± 2.2 for the brown plant hopper as compared to Zingiber officinale which showed percentage mortality rates of 31.1 ± 3.3 for Raffella germanium, 91.3 ± 2.8 for Aedes spp; 91.1 ± 2.5 for Diphtheria spp and 34.4 ± 3.8 for the brown plant hopper. The above result seem to suggest that Piper guineense and Capsicum annum exhibit greater insecticidal potency on the German cockroach (Rhaffella germanium) as compared to Lippia adoensis and Zingiber officinale which showed very high insecticidal efficacy on Diphtheria spp. Also, Piper guineense and Zingiber officinale proved to be highly pesticidal against the mosquito larva (Aedes spp) as compared to the adult mosquito (Anopheles spp) whose percentage mortality rates were not as high as in the case of the larva.