Assessment of extracts from some tropical plants in the management of termite (Termitidae: Isoptera) in Ogun State,Nigeria

This study investigated the efficacy of extracts from four plants, namely: Azadirachta indica, Ocimum gratissimum, Vernonia amygdalina and Nicotiana tabaccum at managing the population of termites in the laboratory and in the field. The synthetic insecticide (Chlorpyrifos 0.1%) and water were included in the study as controls. In the laboratory, contact toxicity was conducted by topical application of the treatments to the thorax of soldier termite Macrotermes bellicossus and mortality noted. The repellent action of the treatments was tested by releasing 10 of the termites into the center of Petri dishes lined with treated filter paper. The number of insects present on the control and treatment halves was recorded and the percentage repellence values were computed. The residual effects of the treatments was studied by placing five termites in Petri dishes lined with filter paper that have been treated with the treatments 24 hours prior to its placement and insect mortality was noted. The studies were conducted using complete randomised design with four replicates. Field trial of the treatments was conducted on termitaria that were demolished and disinfested with five liters of the treatments. The results showed that all the treatments caused 95–100% mean insect mortality 10 hours after insect exposure and have repellence values of between 40 and 65%. The residual effects of the treatments caused termite mean mortality of 100% in Chlorpyrifos and N. tabacum-treated surfaces and between 50 and 65% in others. In the field, only A. indica and Chlopyrifos were effective at curtailing termite upsurge and rebuild of termitaria.