الفهرس 
MATERIAL AND METHODSOnly 14 pages are availabe for public view
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Abstract
In the last few years the hibiscus mealybug,
Ma.conellicoccus hirsutus (Creen), was recorded as an
important pest on orapevines in several vineyards.
Therefore ecolooical studies of M. hirsutus on grapevines
were carried out to give some informations about this new
pest which need for recoiTliTlend i no con t ro 1 programs. The
damaoes caused to vines due to infestation with M. hirsutus
were also investiQated. On the bases of ecological results
and field observations control spray experiments were
conducted to evaluate the efficincy six oroanophosphorus
insecticides. Both ecological and control experiments were
carried out at El-Sef, Giza Governorate and lasted for two
succesive ~ears (1986- 1987 and 1987- 1988).
Results obtained can be summarized in the following
points:
I. Ecological studies:
The seasonal fluctuation of alive population showed
that, M. hirsuts was more active in 1987- 1988 than 1986
1987 season. In the first year the total alive population
had three peaks of seasonal abubdance in 1 £.1 Ju 1 y, 1 s t
November, 1986 and mid-May, 1987, the population index for
the three peaks were 7024, 2255 and 2997 individuals on 80
leaves and 20 twios. In the second year results showed that
the insect followed the same trend and had also three peaks
of seasonal abundance in 1 £.1 July, 1 £.1 November, 1987 and l ”i! May, 1988, the total number of alive individuals were
3815, 3804 and 2025 insects, respectively. It can be
concluded that M. hirsutus had three main period of
seasonal abundance on grapevines under the local conditions
at El-Saf locality. The first period in summer months, the
second during autumn which their individuals overwintered
from November to February, and the third period which began
at early spring and reached its maximum of activity in May
for both years.
With regards to seasonal variations in the different
stages of alive population (1 §1, 2 nd, 3 rd nymphs, adult
females and ovipositing females) throughout two successive
years on grapevines. Results showed that both immatures and
!nature females were found on grapevines allover the year.
Both nymphs and a dult females had four peaks of seasonal
abundance throughout the two seasons. In 1986- 1987 season
the nymphs reached their peaks in 1 ~July, 1 ~November,
1986, 1 §1 February and mid -May, 1987: the mean number
were 4952, 1976, 647 and 2619 nymphs respectively. The
adult females reached their peaks in 1 §1 July, midOctober,
1986: 1st January and mid- May, 1987; the mean
number were 2072, 459, 410 and 377 females respectively. In
the second year, 1987- 1988 results showed that the nymphs
reached their peaks in mid - June, 1 ~ Sept ember 1 s t
November. 1987 and 1 ~May, 1988, the mean numbers were
2489, 995, 1940 and 1209 nymphs, respectively. The adult
females reached their four peaks in 1 g July, 1 g November, 1987, mid- January and 1 §J_ May, 1988, the mean
number of females were 2970, 1864, 1867 and 816 females
respectively.
The number and duration of annual generations were
determined by appling the formula proposed by Audemard and
Mi laire ( 1975) which showed that this species had three
annual overlapping generations in both years under the
field conditions. The first generation began in summer and
lasted 10 - 12 weeks, the second in late summer and lasted
14 weeks and the third. which began in late autumn
individuals of it overwinterd and reached its maximum
activity, in early spring, and lasted 22 - 24 weeks.
The effects of three main climatic factors, i.e.
minimum and maximum means temperature and mean percentage
of relative humidity, on the total alive population of M.
hirsutus on grapevine were investigated throughout three
successive generations during the both years. Results
showed that records of the three tested climatic factors
four weeks earlier were effective on the smoothed halfmonthly
counts (3-figures running means) of the total alive
population.
Results indicated that the mean minimum temperature
had negative effects on the alive population during 1 st
and 2 nd generation summer generation); while it had
positive effects during 3 rd generation (winter and early
spring generation) in both year. With regards to the effects of max1murn medn
temperature 1n the alive population, this factor had
negative effects during summer and autumn generations, in
both years, while the same factor showed miscellaneous
effects during winter and early spring generation in both
years.
The effect of mean percentage of relative humidity on
the total alive population showed that this factor had
negative effect during summer and early spring generations
dur inq both years. On the contrary the same factor had
positive effects on the population of late summer
generation. However, this factor showed variable effects on
the total alive population durinq winter and early sprinq
population~ whereas it had neqative effects in the first
year and positive effects in the second one.
Results of the combined effects of three climatic
factors revealed that the activity of alive population of
M. hirsurus was mostly related to the simultaneous effects
of those climatic factors, four weeks earlier, than the
sinqle effect of each factor separately. The explained
varience ranged from 62.80 93.04 % for the three
qenerations of the first year (1986 1987), and from
73.25% to 91.12% for the second years. The remaining
unexplained varience were assumed to be due to the
influence of other unconsidered factors (biological and
environmental
error. II. Daffidges caused to grapevine due to infestation
with M. hirsutus:
The damages caused to grapevines due to infestation
with M. hirsutus were investigated throughout the morphohistolo<;
pcal changes in grapevine, Vitis vinifera L. var
romi canes artificially infested with hibiscus mealybug.
Symptoms of infestation on different parts of
grapevines were described. On leaves, the leaves and
petioles were turned into dark green; afterwards the leaves
crinkled and lost their symmetrical shapes as a result of
crumpling towards the lower side. The honeydew secreted by
nymphs and adults stimulate the growth of sooty mould. On
stems pronounced retardation of the linnear growth clearly
observed, increase in the number of the internodes, and the
length of them were clearly shorter as well as thickening
in their girth. On flowers, during flowering period
different stages were moved to the flower buds, flowers,
panica!es and berries, then no flowers are formed in heavy
infestation. The infested flowers are crinkled. The
honeydew secretions on the infested flower parts stimulate
the growth of sooty mould on buds, flowers, panicales and
berries.
Histological changes in both infested leaf and stem
were also described. In the leaf tissues, the palisade
tissues were decreased in 1 ength and the spongy tissues
were distorated. The extention of epidermal cells were also
observed. All these effects found to cause the crinkling of the 1nfested leaves. In the stem tissues, the cortical
cells were prolonged in the radial direction, and it was
more obvious in the other cortiacl cells on the collenchyma
tissues. The vascular cylinder was also affected specially
xylem tissues. The affected stem showed an increasing in
the girth of stem tissues due to the cambial activity.
These abnormal growth in both leaf and stem tissues may be
due to the salivary toxin secreted by different stages of
mealybug during feeding into the tissues of the infested
plants.
III. Chemical control experiments:
On the bases of ecological results from previous
studies as well as field observations about M. hirsutus on
grapevines control experiments were carried out. Summer and
winter spary experiments were conducted to investigate the
effect the time of application. The efficincy of six
organophosphorus insecticdes (O.P’s) were examied against
this insect on grapevines throughout two successive years.
Results showed that six O.P’s were fairly effective against
M. hirstus in winter or summer sparys. The statistical
analysis showed that Malathion 0.3 %, Sumithion 0.15% and
Dimethoate 0.125% were more effective with no significant
differences, while Actellic 0.15% Anthio 0.15% and
Tokuthion 0.15 % were less effective and fall in another
separate group. Therefore, any compound of the first group
could be use to control this insect pest on grapevines. JJThe
~1x O.P 1 s wer8 more efficient in summer spctry
oxp~riments than in winter experiments in both years. This
due to the relative high temperature during surruner season.
The effects of the six O.P’s on the different stages
of M. h1csutus showed that the adult females and nymphs
were more sensitive than the ovipositing females which were
more tolerant. This may be due to that both adult females
and nymphs were active and moved on different parts of
grapevines and their bodies were covered with thin wax
secretions, while ovipositing females were less active and
their bodies were covered with thick wax secretions.
For the post - treatment counts, after 1, 2, and 3
weeks after application, results showed gradual increases
in the percentages of reduction in the successive weeks.
These results were insured in both surruner and winter sprays
as well as in the two years. Therefore, the post-treatment
counts must be carried out after not less than three weeks
after application.