9 research outputs found
Effect of Interspecific Competition among Whiteflies (Homoptera: Aleyrodidae) on crops and ornamental plants in Southwestern Nigeria
Whiteflies that are pests of many crops and ornamental plants produce
migratory forms during dense populations with different species sharing
the same host plant. Fields surveys of these pests were conducted from
8 sampling sites within the five states (Lagos, Oyo, Osun, Ekiti and
Ondo states) of Southwestern Nigeria during 2016 and 2019 to
investigate the effects of interspecific competition among whiteflies
on plants in the region. This survey was carried out in both wet and
dry seasons. Whiteflies were collected on crops and ornamental plants
in the sampling sites within the mangrove forest, rainforest and the
derived savannah zones in the region. Interspecific competition was
observed between four species Aleurodicus dispersus , A cocois,
Aleurocanthus woglumi and Bemisia tabaci . The species population of
whiteflies was analyzed using the Paleontological statistics software
package (PAST) and nonparametric t-test was conducted to analyse the
sharing of the host surface among species. The results obtained showed
that the interspecific competition among species of whiteflies in the
region is most during early rain season and yielded less whiteflies
infestation and abundance at underside of plant leaves, and as well
supported high number of the pest on upper leaf surfaces. The
integrative analysis of the consequences of interspecific competition
could provide justification for predicting species exclusion resulting
into whitefly invasions of upper leaf surfaces as their new ecological
niche
Some thermo-physical properties of yam cuts of two geometries
The effects of variation of temperature (-18 to 33°C) and geometries (slab and cylinder) on some thermo-physical properties of white yam were investigated. The measured parameters were density, specific heat, and thermal diffusivity at constant moisture level of 72.7% ± 0.69 (wet basis) using transient heat transfer method. Both the density and specific heat of the sample increased with increase in temperature to maximum levels after which further increase led to a reduction of the values of these parameters; however, they were independent of sample’s geometry. The rate of heat diffusion per second for the yam as measured was between 2.365 to 11.86 x 10-8 m2 and 2.676 to 8.062 x 10-8 m2 for slab and cylinder respectively. The thermal diffusivity and computed thermal conductivity were found to increase with increase in temperature. Conclusively, these thermo-physical properties were correlated with temperature using polynomials of the third order empirical model