| dc.description.abstract | The abundance and economic importance 01 the moth Ephestia
cautella (Walker) on maize grain was established through field
surveys in central storage depots and detailed evaluations
carried out in selected warehouses. Through regular grain
sampling on maize stacks, it was found that moth population
and damage were well correlated and that damage reached 15.26
percent after 8 months of storage. It was found too that this
pest is common throughout the country wherever maize is stored
and that control was a problem even with sustained use of
chemicals.
Population studies were carried out both in the 1ield and in
the laboratory on the moth and its mite predator Blattisocius
tarsalis (Berlese) in a continuous interaction for 33 weeks.
Through life-table analysis, mortality factors regulating the
moth's population were identified where density dependence was
demonstrated on some especially in the first larval instar.
Despite this marked effect of the mite on the moth's
population, and particularly demonstrated density dependence,
mite predator alone was determined to be of limited value in
the control of E. cautella. This was considered to be partly
due to the continuous availability of alternative hosts
especially Tribolium castaneum, Corcyra cephalonica and Plodia
interpunctella which occurred simultane'6usly and in abundant
numbers in the storage 1acilities studied and partly due to
other unknown factors including the architectural design of
the facilities which exposed maize to the environment. This
encouraged re-infestation by the moth and thus interrupted ongoing
regulatory effect of the mite. The alternative hosts
also comprised storage pests themselves whose thresholds could
not be ignored if economic damage was to be avoided. Negative
effects of these alternative hosts otherwise negated their
advantage of providing sustenance to the mite when the moth's
eggs were in low numbers.
Similarly, through 1ield surveys and laboratory screening, it
was found that control with insecticides such as malathion,
pirimiphos-methyl and fenitrothion or with recently introduced
ones like pyrethroids; permethrin and deltamethrin, rarely
eliminated the moth. The use of some chemicals such as
malathion, led to increased populations of the moth after 3
months of application.
The combined use of selected pesticides and mite control
yielded positive results by significantly suppressing the moth
population below economic threshold level. This was
demonstrated in the laboratory cage systems and in normally
operating maize storage warehouses where moth population was
monitored for 8 months with selected insecticide application.
This revealed that integrated control was the most suitable
strategy available to achieve effective pest management of E.
cautella and other associated pests in warehouse storage
systems for maize in Kenya. | en |
