Tolerance of Tithonia diversifolia and Chromolaena odorata in heavy metal simulated-polluted soils and three selected dumpsites.

Soil heavy metals pollution is of global concern in view of their flow through the food chain. The convectional, physical, and chemical approaches to remediate polluted soils are usually expensive and not eco-friendly. Phytoextraction is a promising alternative because of the cost effectiveness and eco-friendliness. Therefore, this study was designed to determine the abilities of Chromolaena odorata (Co) and Tithonia diversifolia (Td) to extract heavy metals from polluted soil. Soil analysis was done in part per million (ppm) before Td and Co were grown separately on sixty soil samples of 6.5 kg each collected from 3 selected dumpsites in Irese, New Stadium, and a control site (Ijare), Akure in Ondo State. Three replicates of the soil samples collected from Ijare were simulated with 10 g/kg each of cadmium (Cd), zinc (Zn), iron (Fe), copper (Cu) and lead (Pb) and used in assessing the phytoextraction capabilities of Co and Td. Two grams per kilogram of each of the heavy metals were mixed together and used in simulating three soil samples collected from Ijare and phytoextraction capabilities of Co and Td assessed. A control experiment using soil sample from Ijare was also set up in three replicates for Co and Td. Soil analyses were also carried out after the experiment in ppm. Plant biomass was assessed. Heavy metal contents in roots, shoots and soil samples were analyzed after harvest to determine the bioaccumulation (BF). Data obtained were subjected to one way Analysis of Variance at α0.05. The most contaminated soil sample before and after the experiment was obtained in soil sample (mg/kg) from OD with Cd = 0.08 and 0.071, Zn = 1.92 and 1.85, Fe = 8.44 and 6.94, Cu = 3.04 and 2.54 and Pb = 1.4 and 0.93 respectively. The highest fresh and dry weights (g) for Td and Co were recorded in the plants grown in the control soil. The fresh weight (g) for Td and Co shoots and roots were 110.58 and 52.90; and 48.41 and 7.18 respectively. The dry weights (mg) for Td and Co shoots and roots were 20.56 and 4.68; and 16.66 and 0.36 respectively. Uptake of heavy metals in T. diversifolia and C. odorata tissues (ppm) were Cd (0.43 and 0.06), Zn (6.57 and 3.8), Cu (3.93 and 2.21), Pb (2.37 and 1.94) and Fe (55.15 and 32.82) respectively. This study showed Tithonia diversifolia and C. odorata were capable of reducing heavy metals in polluted soils. Thus the plants are good candidates for the phytoextraction of heavy metals from polluted soils.

Toxicological evaluation of the essential oil from Mentha longifolia L. subsp. capensis leaves in rats.

The effects of the essential oil from the leaves of Mentha longifolia L. subsp. capensis on some biochemical parameters of Wistar rats were studied. The oil at 125, 250, 375, and 500 microL/kg of body weight reduced (P < .05) the red blood cells and lymphocytes with no definite pattern on the white blood cells and mean cell volume. The doses significantly increased the neutrophils, monocytes, large unstained cells, liver-body weight ratio, and serum concentrations of cholesterol, triglyceride, high-density lipoprotein-cholesterol, and inorganic phosphate but had no effect on the heart body weight ratio and serum low-density lipoprotein-cholesterol, Na(+), Ca(2+), Cl(-), K(+), creatinine, and uric acid. The oil at 500 microL/kg of body weight also increased the kidney-body weight ratio. In contrast, the oil reduced the serum urea and atherogenic index. The total and conjugated bilirubin, together with the total protein and albumin, in the serum increased only with oil at 125 microL/kg of body weight. The serum alkaline phosphatase activity also increased with no significant change in those of gamma-glutamyl transferase and alanine and aspartate aminotransferase. The results indicate dose- and parameter-specific effect of the essential oil. Although the essential oil from M. longifolia leaves may not predispose to atherosclerosis, it may increase the functional activity of the rat liver at the lowest dose investigated. Therefore, the essential oil from M. longifolia may not be completely "safe" at the doses investigated.

Effect of rearing temperature on the fecundity and development of Euzopherodes vapidella Mann (Lepidoptera: Pyralidae), a pest of stored yam.

The fecundity and development of the yam moth, Euzopherodes vapidella Mann on Dioscorea alata L. was investigated in the laboratory at four different temperatures, 20, 24, 29 and 33 degrees C. The mean fecundity per female at 20, 24, 29 and 33 degrees C was 51.8+/-3.5, 102.4+/-3.8, 123.3+/-4.4 and 124.4 +/-4.4 eggs, respectively. Hatchability of eggs was highest at 29 degrees C and lowest at 20 degrees C. The mean developmental time at 20, 24, 29 and 33 degrees C was 12.1+/-0.6, 6.2+/-0.3, 3.0+/-0.0 and 2.7+/-0.1 days for the egg, 23.6+/-1.1, 20.0+/-0.9, 15.4+/-0.7 and 12.9+/-0.4 days for the larval stages, 13.0+/-0.03, 8.9+/-0.02, 7.9+/-0.02, and 6.4+/-0.03 days for the pupa and 48.7+/-3.5, 35.1+/-2.3, 26.3+/-1.2 and 22.0+/-1.0 days for the period from egg to adult emergence, respectively. The developmental threshold for the egg stage was estimated as 16.8 degrees C with thresholds of 8.0, 6.2 and 11.4 degrees C for larvae, pupae, and egg to adult emergence, respectively. Storage of yam tubers at low temperatures (but higher than 12 degrees C to avoid damage to tubers) will significantly retard the development of E. vapidella and therefore help in their control. Adult males ranged from 0.50 to 0.65cm in length and females from 0.70 to 0.90cm.