Inhabited Macrotermes (Termitidae: Macrotermitinae) mounds in cultivated farms in the humid forest agroecological zones of southwestern Nigeria showed higher clay and silt but lower sand contents than their surrounding soils. These physical characteristics were positively correlated with those of the surrounding soils. The heights and diameters of the mounds were also positively correlated to the level of clay and silt in the surrounding soils, although the correlations were not significant (P > 0.05). Carbon and nitrogen content of 67% of the mounds was lower than that of their surrounding soils. A general increase in exchangeable bases and phosphorous contents of the mound materials compared to those of the surrounding soils was also observed. The pH of mound materials varied between 5.5 and 7.3, with 75% of the mounds having lower pH values than the surrounding soils. The implication of these results on the possible use of mound materials to increase soil fertility is discussed.

During surveys conducted in 40 maize-cassava intercrops in the humid forest zone of southwestern Nigeria, the following termite species were identified from soil samples: Microtermes spp., Macrotermes nigeriensis (Sjöstedt), Macrotermes subhyalinus (Rambur), Amitermes evuncifer (Silvestri) and Anoplotermes quietus (Fr. Muller). High incidence of Microtermes and Macrotermes spp. was observed. The population density of predominant species was generally higher in the rainy seasons than in the dry seasons, indicating the role of moisture in their spread. The soil texture of surveyed farms did not influence the presence of the subterranean species Microtermes. The level of weeds in the surveyed farms also did not affect the population density of termites. However, Microtermes population increased significantly (P < 0.05) with increase in crop residues and its presence in farms partly depended on the presence of maize in such farms. Microtermes and Macrotermes species inflicted most of the damage observed on maize crops, while that caused by Amitermes evuncifer was low. No termite attack was observed on growing cassava during the surveys. The presence of live cassava in the intercrop did not influence damage by termites. Nasutitermes and Microcerotermes species which attack economic trees such as cocoa, citrus, oil palm, and forest trees did not attack cassava or maize.

Aqueous extracts (5%) of the seeds Parkia clappertoniana (Jacq), Azadirachta indica A. Juss, and Piper guineense Schum and Thonn caused 90% mortalityof the worker caste with P. guineense, and 86% mortality with A. indica and P. clappertoniana respectively within 3 hr of topical application. At 24 hr, mortality of Macrotermes nigeriensis (Sjostedti) workers was 100% with the same concentration of each extract. Oral toxicity at 3 hr to the worker caste using cuttings of cassava, Manihotesculenta Crantz impregnated with each extract gave 65% mortality with Piper, and 45 and 29% with Azadirachta and Parkia, respectively. Mortalityby oral toxicity reached 100% in 12 hr with Piper, 95 and 69%, respectively with Azadirachta and Parkia. Increasing the concentrations of each extract to 15% did not significantly (P > 0.05) increase the toxicities of the extracts to the worker caste even at prolonged exposure periods.