الفهرس 
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Abstract
SUMMARY
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Laboratory reared strains of two species of flour b~etleB
i.e. Tribolium castaneum and Tribolium confuaum were reared
for five generations under pressure of insecticides. The
insecticides used were malthion, cypermethrin and decamethrin
parent s ani Burvivals of insecticidal ~ selection were fUrther
exposed to two levels of insecticides. the 1C50 level (sublethal
dose) and a concentration causing no mortalities among adults
(non lethal dose ) and the biology of each case was recorded.
Rsults of rearing under pressure revealed various degrees
and steps towards aquiring resistance in each insecticide. insect
species, indicating a different gene set up in each case.
In malathion selections, there waS a substantial increase in
slope of the LD p-line in FS in T. castaneum whereas T.confusum
under went slight changes in slope in the five generations investigated.
This might be taken to indicate that T. castaneum
would aquire resistance to malathion in lesS generations than
re qlired by T. confusum.
~hen cypermethrin was tested, the results indicated that
th~ five generations of both insect species reared under pressure
represented a Lat ent period during which accumula’tion or subsid”~
J gene alleles takes plaae alongside a remodelling of
the genotype as a whole to accomodate the new gene allele.
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Using decamethrin for selection in T. castaneum revealed
th8t the first two generations served to eleminate tl~ extremely
susceptible insects and the first steps towards tolerance
could be detected from F) cnvards. In T. confuSUIn, however
the five generations investigater were enough to produce a
tipical tolerent strain with a low slope and ”LC50value being
7.3 folds longer than the parents.
It was concluded that the two species of flour beetles
were cupable of producing tolerent strains of the three insecticides
investigated, although the pattern and number of generations
required would differ in each species toxicant combination.
’rile slo’Nest build u, to resistance, would be expected
with cypcrrnet””rin, while the fastest build up would eccurr
e
with
dec me’~hrin andi.’. confusum.
vnen the efi~ect of LC
5C
and non lethal doses of the three
toxic ants wer invest igat ed on the t’.0 insect specie s select ed
for tolerance all the insecticides used excerted deleterious
effect s on the biolog.y of the parent 8 and subsequent generat ions
selected for tolerance. The degree of
pre~nt. effect on oviposition,
hatchability, Larva.L ani pupal development periods
and longevity of adult s varied considerably with various insecticides.
Selection for tolerance in BOI!l9 acases tended to
partiall’ mitig te the effecta recorded for toe untreated parent
s wni.Le in other case s an imp-ession was gained of the
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141
presence of an adverse additive effect of selection for tolerance
andexposure to sublethal doses •
rne level of trel:1”tmentto produce activation of the biological
activities, reported for other insects was not detected
in the present work, it was concluded that if a threshold
for stimulatory effects of malathion, cypermethrin and decamethrin
on the two flour beetles, then if must be farbelow the
range of concentration used to build LD-p-line.