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Molecular Entomology
27
play a vital role in the development of insect pests
fluctuation of these causes variation in the
population present study was designed to
investigate the effect of temperature and relative
humidity on population of some insect pests of maize
in unsprayed condition. Keeping in view the scenario
regarding pest attack on maize crop the presented
study was planned to investigate the effect of
temperature and relative humidity on some insect
pest of maize varieties.
1 Result and Dissuction
The present study carried out on the effect of
temperature and relative humidity on the infestation of
population of some insect pest of maize in Kharif
crops. The results indicated that the population of leaf
hoper increases with increase in temperature and
decrease in relative humidity as the highest population
of leaf hopper (mean value = 1.95) at the temperature
of 36.2
℃
and relative humidity at 75% while, the
lowest population of the leaf hopper was found (mean
value = 0.65) at the temperature of 30.5
℃
and relative
humidity 83%. (Table 1). (Zulfikar et al. 2010). found
he results show that the population of leaf hoper
increases with increase in temperature and decrease in
relative humidity as the highest population of leaf
hopper (mean value = 1.70) at the temperature of
36.5
℃
and relative humidity at 68% while, the lowest
population of the leaf hopper was found (mean value
= 0.55) at the temperature of 31.5
℃
and relative
humidity 75% While the infestation of jassid
experiment indicted that the population of jassid
increases with increase in temperature and vice versa
So that temperature and relative humidity highly
significant on jassid population the lowest population
of jassid was found with mean value of 0.80 at 28.6
℃
and relative humidity 73% and the highest population
of jassid found (mean value = 1.95) at 36.0
℃
and
relative humidity 75%. (Table 2) These finding were
confirmed (Suggetha, 2001) he found the optimal
conditions of temperature and relative humidity for
the population build up of jassid at the temperature
30
℃
and relative humidity 60.75% (Tamiru et al.,
2012). The spotted stemborer,
Chilo partellus
(Swinhoe) (Lepidoptera: Crambidae), is one of the
most important insect pests attacking maize and
sorghum in Ethiopia. Recent studies have indicated
that the pest is spreading to new locations where it
was not reported before. In the current study,
laboratory investigations were carried out to determine
the combined effect of different levels of relative
humidity and temperature regimes on the development
and fecundity of
C. partellus
, as these physical factors
are known to play an important role in the life cycle of
insects and adaptability to local
climate.
Developmental time, longevity, potential fecundity
and realized fecundity of
C. partellus
were measured
under controlled conditions. Three temperature
regimes (22
℃
, 26
℃
and 30
℃
) and three relative
humidity levels (40%, 60% and 80%) were tested. It
was found that temperature; relative humidity (RH)
and their interaction significantly affected the
developmental time, adult longevity, potential
fecundity and realized fecundity of the pest.
Developmental time was inversely related to
temperature. Mean duration of
C. partellus
life cycle
was 70.2 days at 22
℃
and 80% RH, whereas it took
only 26.5 days to complete its life cycle at 30
℃
and
40% RH. Male and female longevity were similar in
most cases. The adult life span ranged between
6.9~11.1 days at 22
℃
and 3.1~7.2 days at 30
℃
for
different levels of relative humidity. The most suitable
conditions for
C. partellus
development and fecundity
were 26
℃
~30
℃
temperatures regimes and 60%~80%
RH levels. The infestation of
Chilo partellus
in this
experiment increased with decrease in temperature
and relative humidity. The minimum infestation
20.2% was found at the temperature of 31.2
℃
and
relative humidity 75%. Maximum infestation 55%
was found at temperature of 29.5
℃
and relative
humidity 85% (Table 3). The population of aphid
increase with decrease in temperature and relative
humidity, lowest population was fund (mean value
2.32) at temperature 30.4
℃
of and relative humidity
83% of and the highest population was found (mean
value 3.12) at temperature 30.1
℃
and relative
humidity 85.5% (Table 4).
Molecular Entomology