الفهرس 
Seasonal abundance of Saccharicoccus sacchariOnly 14 pages are availabe for public view
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Abstract
The mealybug, saccharicoccus sacchariis one of the major pests of
sugarcane (virginal and first ratoon) in Egypt, especially in upper Egypt.
The present work aimed at throwing light on certain aspects of its ecology
that included, the seasonal activity, stage structure, rate of monthly
variation, estimated number, duration and predication of annual field
generation and effect of main climatic factors on the seasonal activity of
this pest. Finally, effect of infestation on some physica l and chemical
properties of sugarcane caused by this pest at Nag-hammadi, Qena
Governorate during two successive seasons of (2012/2013 and
2013/2014).
The obtained results of these studies could be summarized as follows:
5.1 Ecological studies :
5.1.1. Seasonal population trend of the Pink sugarcane mealybug,
saccharicoccus sacchari(Cockerell).
5.1.1.1. The first growing season of 2012 / 2013.
5.1.1.1.1. Nymphs population
Results revealed that the nymphs population of S. saccharihad two
peaks abundance on the virginal and 1
st
ratoon cane, the highest in 4
th
week and 3
rd
week of September in both virginal and 1
st
ratoon cane,
respectively. The lowest in 4
th
and 2
nd
week of May in both virginal and 1
st
ratoon cane, respectively.
5.1.1.1.2. Adult females population
Results revealed that the Adult females population of S. sacchari
showed two peaks, the highest in 4
th
and 3
rd
week of September in both
virginal and 1
st
ratoon cane, respectively. The lowest in 1
st
week of May in
both virginal and 1
st
ratoon cane, respectively.
5.1.1.1.3. Total population (Nymphs and Adult females)
Results indicated that total population of S. sacchari also, had two
peaks, the highest in 4
th
week and 3
rd
week of September in both virginal
and 1
st
ratoon cane, respectively. The lowest in the 2
nd
week of May in
both virginal and 1
st
ratoon cane, respectively.
5.1.1.2. The second growing season of 2013 / 2014.
5.1.1.2.1. Nymphs population
Results indicated that nearly similar results obtained in both
seasons. The nymphs population of S. saccharihad two peaks, abundance
during the second season 2013/ 2014. The highest in 4
th
and 3
rd
week of
September in both virginal and 1
st
ratoon cane, respectively. The lowest in
1
st
week of May in both virginal and 1
st
ratoon cane, respectively.
5.1.1.2.2. Adult females population
Results revealed that the Adult females population of S. sacchari
had two peaks, abundance during the second season. The highest in 4
th
and 3
rd
week of September in both virginal and 1
st
ratoon cane,
respectively. The lowest in 3
rd
and 4
th
week of May in both virginal and 1
st
ratoon cane, respectively.
5.1.1.2.3. Total population (Nymphs and Adult females)
Results revealed that the same trend observed. The highest total
population of S. sacchari in 4
th
week of September in both virginal and
1
st
ratoon cane. The lowest population in 3
rd
week and 4
th
week of May in
both virginal and 1
st
ratoon cane, respectively. Average number were
fluctuated through the two growing seasons and through the four
plantations, this may be due mainly to the prevailing weather factors.
The results show also that the overall season grand total of phytophagous
pest (Nymphs + Adult females) on the 1
st
ratoon cane was higher than that
on the virginal cane during both seasons.
Meanwhile the seasonal grand total of the adult females during the
1
st
ratoon cane was higher than that recorded during the virginal cane
during two growing seasons and the vice versa was obtained respecting
the seasonal grand total of the nymphs. On the other hand, although the
population density ofS. sacchari(Nymphs + Adult females) had different
levels of abundance through the four plantations during two studied
seasons, the trend of the population oscillations in the two seasons was
similar. Furthermore, results of present study indicated also that the S.
sacchari was more active during summer and autumn, where the
maximum population was observed during August, September, October
and November while, its activity was lowered during winter and spring
months.
The highest percentage of the overall year count of nymphs (13.9,
13.1%) and (21.4 and 17.1%) from the grand total were recorded in
September on the virginal and 1
st
ratoon cane during two growing seasons.
While, adult females were (13.4, 11.2% and 16.9, 16.4%) from the grand
total on the virginal and 1
st
ratoon cane, respectively, during two growing
seasons. Moreover, the lowest percentages of the nymphs were (5.4%,
6.7% and 3.3%, 5.6%) on the virginal and 1
st
ratoon cane, respectively
through the first and second seasons respectively.
Meanwhile, the adult females were (6.2%, 7.1%) recorded in Jan.
and (5.7, 6.9%) on the virginal and 1
st
ratoon cane through the two season
2012/2013 and 2013 /2014 respectively. Also the insect population was
higher in autumn months and thus due to the environmental condition
which were more suitable for the insect activity.
5.1.2. Estimation of insect stage - structure population for the S.
sacchari inhabiting sugarcane plants.
The results revealed that, the percentage of the stage-structure
population of S. sacchari during both growing seasons, were almost
similar. Nymphs population were represented by 80.35and 82.16% out of
the total population during both virginal and 1
st
ratoon cane respectively,
through the first season 2012/2013. On the other hand nymphs were
represented by 79.18% and 83.56% out of the total population during both
virginal and 1
st
ratoon cane, respectively during the second season
2013/2014. On the other hand, adult females were represented by 19.65
and 17.84% out of the total population, during both virginal and 1
st
ratoon
cane, respectively during the first season 2012/2013. Meanwhile, adult
females were represented by 20.82 and 16.44% during both virginal and
1
st
ratoon cane, respectively, through the second season 2013/2014.
However, the insect stage - structured population was considerably
differed among months and between the plantation through two studied
seasons.
5.1.3. Rate of monthly variation (R.M.V.P.) in the population of pink
sugarcane mealybug, saccharicoccus sacchari during two successive
growing seasons of 2012 /2013 and 2013/2014.
As for nymphs results indicated that the favourable time of annual
increase appeared to be in August, September, June and February on the
virginal cane. While, it appeared to be in August and September on the 1
st
ratoon cane during the first growing season of (2012/2013). Meanwhile, it
occurred in September, July and February on the virginal cane.
While, it occurred in August, September, and February on the 1
st
ratoon cane during the second growing season of 2013/2014. The rate
monthly variation of the adult females showed that the favourable times
for annual increase seemed to be in August, September, July and February
and September, August, February and July on the virginal and 1
st
ratoon
cane, respectively during the first season of 2012/2013. While it seemed to
be in August, July and February and in September, August and February
on the virginal and 1
st
ratoon cane, respectively through the second season
of 2013/2014.
from the results obtained, it can be concluded that the favourable
times for annual increase of both stages (Nymphs and adult females
together) occurred June, August, September and February, during the first
growing season. While it July, August, September and February, during
the second growing season. Generally, it seems that summer months are
the favourest for the population growth and activity of S. sacchariunder
circumstances of QenaGovernorate.
5.1.4. Effects of certain weather records on the activity of S. sacchari
inhabiting sugarcane plants. ( virginal and 1
st
ratoon cane).
Weather factors play a great role in the population abundance of
many insect species. Therefore، some physical factors, particularly
temperature and relative humidity, were investigated in the present study
to declare their simultaneously effects on the population density of S.
sacchari . The studied weather factors were statistically analyzed by
simple correlation and partial regression analysis.
5.1.4.1 Virginal cane
5.1.4.1.1. Effect of mean max, min and relative humidity.
Statistical analysis indicate that air temperature expressed as daily
maximum, and daily minimum temperature were highly significantly
positive for the 1
st
season and insignificant positive for the 2
nd
season for
nymphs, for adult females and for both together during 2012 /2013 and
2013/2014 seasons. Generally, daily mean relative humidity were
insignificant negative correlation for 1
st
season and insignificant positive
correlation for 2
nd
season on the population of nymphs, and adult females
and total population during the two seasons of study.
5.1.4.1.2. The combined effects of certain weather records.
The partial regression analysis revealed that the tested variables
together were responsible for 73.0 and 22.27%for nymphs population,
72.0 and 28.29% for adult females,73.0 and 22.5% for the total population
during the 1
st
season and 2
nd
season, respectively.
Summary
123
5.1.4.2. 1
st
ratoon cane
5.1.4.2.1. Effect of mean max., min., temperature and relative
humidity.
Obtained results indicate that air temperature expressed as daily
maximum and daily minimum temperature were highly significant
positive for the 1
st
season (2012/2013) for nymphs, adult females and total
population, while were insignificant negative for nymphs and total
population, insignificant positive for adult females during the second
season (2013/2014).
Generally, daily mean relative humidity were significantly
negative for nymphs, for adult females and total population during the
first season (2012/2013). Meanwhile, were insignificantly positive for
nymphs, total population and insignificant negative correlation for adult
females during the second season (2013/2014).
5.1.4.2.2. The combined effects of certain weather records.
The partial regression analysis revealed that the tested variables
together were responsible for 57.0 and 23.6% for nymphs, 64.0 and
24.57% for adult females and 58.0 and 22.56% for the total population
during the 1
st
season and 2
nd
season, respectively.
5.1.5. Number, duration and size of annual generation of S. sacchari
during two successive seasons of 2012 /2013 and 2013/2014.
5.1.5.1. The first season of (2012/2013).
Two generations were recorded during each of plantation. During the
virginal cane, the 1
st
generation was from the beginning of May to July 8
and lasted 69 days. The 2
nd
generation was from July 8 to January 22 and
lasted 198 days. These generations size were 2880 and 7451 individuals
/10 stalks, respectively. During the 1
st
ratoon cane, the 1
st
generation was
from 1
th
of May to July 8 and lasted 69 days. The 2
nd
generation was from
July 8 to January 22 and lasted 198 days. These generations size were
3555 and 9146 individuals/10 stalks, respectively.
5.1.5.2. The second season of (2013/2014).
Also two generations were recorded during each of plantation.
During the virginal cane, the 1
st
generation was from May 1 to Jan 22.,
and lasted 53 days. The 2
nd
generation was from
June
22, to Jan 15., and
lasted 69 days. These generations size were 647 and 5826 individuals/10
stalks. During the 1
st
ratoon cane, the 1
st
generation was from May1, to
July 8 and lasted 69 days. The 2
nd
generation was from July 8 to Jan 15.
and lasted 192days. These generations size was 1406 and 7391
individuals/10 stalks, respectively.
5.1.6. Heat units of each generation.
5.1.6.1. The first season of (2012/2013).
The results showed that the second generation of S. sacchari was
higher the total accumulated heat units (AHU) was estimated to be 1891.9
units which required for the development of this generation on the virginal
and 1
st
ratoon cane which required for the development of this generation
and was least the daily degree-days per generation was estimated to 9.72
(DD
’
S) during the virginal and 1
st
ratoon cane as compared the first
generation. On the contrary the first generation during both plantation was
lower once in the accumulated heat units of S. sacchari were (1036.5
units to both virginal and 1
st
ratoon cane) which required for the
development of the first generation and was higher ones in the mean daily
degree-days was estimated (15.44 DD
’
S) of both plantation. As compared
with the second generation.
5.1.6.2. The second season of (2013/2014).
The results showed that the second generation of S. sacchari was
higher the total accumulated heat units (AHU) was estimated to be
1930.69 and 1706.7 units of virginal and 1
st
ratoon cane respectively,
which required for the development of this generation and was least the
mean daily degree-days per generation was extended to be 9.67 and 9.18
(DD
’
S) in both plantation. On the contrary the first generation during both
plantation was lower in the accumulated heat units (DD
’
S) of this pest
were (854.50 and 961.5) which required for the development of this
generation and was higher ones in the mean daily degree-days were
estimated (15.43 and 15.41 DD
’
S) as compared the second generation
during this season.
5.1.7. Predicting of annual generation peaks of S. sacchari using
thermal units accumulations:
5.1.7.1. The first season of (2012/2013).
The obtained results revealed that there was a discrepancy between
observed and expected peaks with an average of -10.0 and -15.9 days for
both the virginal and 1
st
ratoon cane during the first growing season. For
both plantation (virginal and 1
st
ratoon cane) as a whole the general
deviation average indicated that the expected peak were detected delayed
than the observed one with an about 12.75 days. Also, the predicted peaks
of generations could be detected when the accumulated thermal units
reached 1212.25 degree-days.
5.1.7.2. The second season of (2013/2014).
Results revealed that there was a discrepancy between observed and
expected peaks with an average -41.5 days for both the virginal and 1
st
ratoon cane during the second season.
For both plantation (virginal and 1
st
ratoon cane) as awhole, the general
deviation average showed that the expected peak were detected delayed
than observed one with an about 41.5 days.
Also, the predicted peaks of generations could be detected also when
the accumulated thermal units reached 1212.25 degree-days. Proper
timing for control of S. sacchari two periods can be recommended for
chemical control of this pest where the relative abundance of first instar
nymphs was the most. The first period is during beginning of 15
th
of May
and 22
th
of May to reduce the population summer. The second timing is
22
th
of Sept. and 15
th
of Sept. on the virginal and 1
st
ratoon cane,
respectively to reduce the population in the autumn during the two
successive seasons.
5.2. Effect of infestation with S. sacchari on certain properties of
sugarcane at harvesting time on the Virginal and 1
st
ratoon cane
during two successive seasons of 2012 /2013and 2013/2014.
5.2.1. Effect of infestation with S. sacchari on the physical properties.
Results indicated that infestation with pink sugarcane mealybug
S. sacchari decreased significantly physical parameters for both stalk
weight, stalk length, internodes length and juice weight than that
uninfested ones. Also the reduction % was significant between infested
stalks and uninfested ones during virginal and 1
st
ratoon cane and first
ratoon cane is more susceptible to the infestation with S. saccharithan in
the virginal cane.
5.2.2. Effect of infestation with S. sacchari on the chemical properties.
Results indicated that infestation with S. sacchari of sugarcane
plant reduced gradually and significantly all chemical properties for Brix,
sucrose%, purity, pol and sugar recovery than that uninfested plants
except Glucose % increased in infested plant than uninfested plants. Also
the reduction % was significantly between infested stalks and uninfested
ones and first ratoon cane suffer more reduction than the virginal cane
during two seasons.
5.2.3.Effect of infestation with S. sacchari on cane and sugar yield of
sugarcane (ton/ fed).
Results showed that the reduction in cane and sugar yield increased
gradually in infested plants than uninfested plant and susceptibility to
infestation was less in virginal cane than in the first ratoon cane