Development And Competition In Rice Weevil, Sitophilus Oryzae (L.) And Red Flour Beetle, Tribolium Castaneum (Herbst), And Their Responses To Active Compounds In Selected Spices.
Loading...
Date
2016
Authors
Wong, Nellie Su Chee
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Stored product insects causes more than 20 % in total damages to stored
products in developing countries and 9 % in total damages to stored products in
developed countries on a yearly basis. Food security is threatened especially with the
rapid increase in world population. This thesis focuses on the behavioural and control
aspects of Sitophilus oryzae (L.) and Tribolium castaneum (Herbst). Both are two of
the most common stored products insect attacking stored products in tropical
countries. A study on the insects’ development rates in different mediums were
carried out. Sitophilus oryzae were exposed to unpolished brown rice, local polished
rice, parboiled rice, calrose rice basmati rice, red rice, black glutinous rice and
fragrant polished rice. The weevils preferred mediums with lower carbohydrate
contents but higher contents of ash and fibre. Eight types of flour and starch (atta
flour, enriched wheat flour, self-rising flour, rice flour, custard powder flour, corn
flour, tapioca starch, and potato starch) were used to rear T. castaneum and the
beetles developed well in mediums with higher protein contents, while high
carbohydrate contents were detrimental to their development. Competition between
and within the species is dependent on the initial population density. In the
intraspecific study, the fecundity of S. oryzae and T. castaneum was reduced above
and below a certain initial population density. However, the interspecific study
showed that an increase in initial density of T. castaneum has a gradual negative
impact on the progeny development of S. oryzae but no effect vice versa. Both insect species were exposed to five spices (Elettaria cardamomum (L.), Brassica nigra (L.),
Rosmarinus officinalis L., Capsicum frutescens L., and Cassia auriculata L.) in both
whole and powdered form. Although high mortality was not recorded when the
insects were exposed to the whole formed spices, but S. oryzae was more susceptible
than T. castaneum. Among the spices tested, the powdered form of E. cardamomum
was most effective against both insect species. Finally, a study to determine the
repellency effects of extracted materials from the spices against the test insects was
carried out. Elettaria cardamomum was again found as the best repellent candidate.
The presence of aromatic hydrocarbons, esters, acid esters, carboxylic acids as well
as some unknown compounds may have attributed to the repellent property of the
spice.
Description
Keywords
Sitophilus oryzae (L.), Tribolium castaneum (Herbst).