Bio-accessibility and health risk assessment of some selected heavy metals in indoor dust from higher institutions in Ondo State,Nigeria

Environmental Science and Pollution Research - Risks of heavy metal exposure from contaminated indoor dust constitute a major threat to human health. In this paper, heavy metals in deposited indoor...     

Perceived causes, exposures and adjustments to seasonal heat in different residential areas in Ibadan, Nigeria

Local perception can be an important resource for assessing and managing climate-related extremes and identifying adjustment strategies unique to specific settings. The objectives of the study are two-fold. Firstly, it examined the perceived causes, exposures and adjustments to seasonal heat events using different residential density areas of Ibadan, Nigeria, as spatial units of analysis. Secondly, it investigated the relationship between heat exposure, built environment, socio-economic and cultural factors. Results show that intense heat from the sun, climate change and absence of rains, among others, was identified as perceived causes. Number of electricity hours, distance from water supply points and the number of neighborhood trees were listed as the three most important factors affecting heat exposure. In addition, there were considerable variations in the perceived causes (F?=?4.86, p?<?0.05), in exposures (F?=?3.61, p?<?0.05), and in adjustments to seasonal heat (F?=?8.75, p?<?0.05) across different residential density areas in Ibadan, Nigeria. The study demonstrates that local knowledge based on the perceptions, exposures and adjustments to seasonal heat waves has the potential in some cases to provide valid inputs into vulnerability and adaptation assessments.     

Attraction of two larval parasitoids with varying degree of host specificity to single components and a binary mixture of host-related plant volatiles

As an indirect defense to herbivore attack, plants release many types of volatile organic compounds (VOCs), which guide parasitoids to their herbivore hosts. In the present study, VOCs were categorized as those released passively from undamaged plants and herbivore-induced plant volatiles (HIPVs). HIPVs were further categorized into: (1) volatiles released by fresh damage plants, and (2) volatiles released by old damage plants. We used as models, two parasitoids with different degree of host specificity, Microplitis croceipes (specialist) and Cotesia marginiventris (generalist), to address the evolutionary and mechanistic question of whether specialist and generalist parasitoids differ in their use of VOCs for host location. Both species are solitary larval endoparasitoids in the same family (Hymenoptera: Braconidae) and are important parasitoids of caterpillar pests of cotton. Based on the results of previous studies, α-pinene, (Z)-3-hexenol, and (Z)-3-hexenyl acetate were selected as representatives of the different types of VOCs in cotton. The attraction of both parasitoid species to synthetic components and a binary mixture of the above VOCs was tested in four-choice olfactometer bioassays. Female M. croceipes showed the greatest attraction to the HIPVs while female C. marginiventris could not discriminate among the three VOCs. Conspecific males showed similar responses with a few exceptions. When presented with the choices; α-pinene, (Z)-3-hexenol and a binary mixture (50:50v/v) of the two compounds, the specialist showed the greatest attraction to the mixture. However, the mixture did not elicit such an additive effect on the attraction of the generalist. Overall response latency (time taken to choose VOCs) indicated species and sexual (in the specialist) differences. Using a simple model, this study provides a fundamental insight into odor preferences and discriminatory ability of the test parasitoids. The ecological significance and practical implications of these results are discussed.