الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
SUMMARY
The present study was carried out to evaluate the efficiency of six
toxicants from different groups against the prepupae of the peach fruit fly,
Bactrocera zonata.
1. Effectiveness of six toxicants against prepupae, pupae and
adults of the peach fruit fly, Bactrocera zonata:
The toxicity of the organophosphorus insecticides; Malathion,
Dimethoate, Actellic, the miscellaneous toxicant, Abamectin, the
entomopathogenic fungi, Bio-power and the entomopathogenic
Nematodes to the prepupae (full grown larvae) ,pupae and adults of the
peach fruit fly, B. zonata was studied.
1.1. Effect of organophosphorus insecticides ( Actellic, Malathion and
Dimethoate):
Exposure of prepupae and pupae of the peach fruit fly, B. zonata to
sandy soil treated with reasonable concentrations of Malathion,
Dimethoate, and Actellic caused obvious mortality of the pupae. The two
insecticides; Dimethoate and Actellic showed no effect against prepupae;
whereas, Malathion showed slight effect against the prepupae at the
concentrations of 5000 and 6000 ppm.The two toxicants; Malathion and
Dimethoate had slight latent effect against the emerged adults; while
Actellic showed no latent effect against the emerged adults. Generally,
Actellic was more toxic against the adults of B. zonata than Malathion
and Dimethoate.
SUMMARY
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1.2. Effect of the Miscellaneous insecticide; Abamectin,
entomopathogenic fungi and entomopathogenic Nematodes:
The toxicity of the miscellaneous toxicant, Abamectin and the
entomopathogenic agents; fungi, Bio-power, Beauvaria bassiana and
Nematodes, Sternernema feltiae against prepupae, pupae and adults of
the peach fruit fly, Bactrocera zonata was studied.
Exposure of the prepupae and pupae of the peach fruit fly, B. zonata
to sandy soil treated with reasonable concentrations of the miscellaneous
toxicant, Abamectin was effective against the pupae and has no effect
against the prepupae. Also, the toxicant had no latent effect on the adults
emerged from treated prepupae.
Data of the present study showed that the Bio-power was highly
effective against the pupae and had no effect on the prepupae. Also, the
toxicant had no latent effect against the emerged adults.
Results showed that S. feltiae was effective against the pupae and
had no effect on perpupae. S. feltiae had no latent effect on the emerged
adults from treated perpupae of B. zonata.
2. Total toxicity of the six toxicants:
The total toxicity of the different concentrations of each toxicant
was determined on the basis of the dead individuals of three stages ;
prepupae, pupae and adults. The total mortality rates were used in
drawing the toxicity lines . the toxicants were evaluated according to the
following basis:
SUMMARY
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2.1. Comparison on basis of LC50 and LC90 values:
The obtained results show that the miscellaneous toxicant; i.e.
Abamectin was the most pronounced toxicant against prepupae of the
peach fruit fly, B. zonata at LC50 and LC90 values.
2.2. Comparison on basis of toxicity index and potency levels:
In this study, the toxicity index was used as a mean for comparing
the relative toxicity of insecticides against the prepupae of the peach fruit
fly, B. zonata . The miscellaneous toxicant; Abamectin was taken as the
standard insecticide and given arbitrary index value 100 units to study the
toxicity index of the other five toxicants as compared with this standard
toxicant.
Also, relative potency level can be used as a convenient method in
comparing the degree of toxicity of different toxicants to any pest. The
potency levels of tested toxicants are expressed as the number of folds, at
the required toxicity level, compared with the least effective toxicant
included in the evaluation against the tested insect. Bio-power was
considered the standard toxicant..
2.3. Comparison on the slope of toxicity lines:
The present study showed that Abamectin had the steepest toxicity
line followed by Actellic and the entomopathogenic Nematodes, whereas
Bio-power had the flattest toxicity line when the six toxicants were tested
against the prepupae of B. zonata. On the other hand, Malathion and
Dimethoate occupied medium situation of the toxicity lines among the six
toxicants used in this study. Hence, the six toxicants had three trends of
slopes, the steepest being that of Abamectin, Actellic and Nematodes
followed by Malathion and Dimethoate then Bio-power having flattest
toxicity lines.
SUMMARY
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The above mentioned conclusion is correct whether it is the slope
values or LC90 /LC50 ratios, since the later method simply expresses the
steepness of the LC-P lines in a reversal way to the slope values.
Therefore, an increase in the slope value or a decrease in the LC90 /LC50
ratio indicates an increase in steepness of the toxicity line.
2.4. Persistence of the six tested toxicants:
The exposure of the prepupae to treated soil with different
concentrations of the six toxicants and determination of their efficiency
after 0,3,6,9,12,15and18 days by measuring the total toxicity have been
studied. The practical proposed concentrations for field application
against B. zonata of Malathion, Dimethoate, and Actellic are 5000, 7500
and 10000 ppm, respectivily. Also, the recommended concentrations of
miscellaneous toxicant; Abamectin, the entomopathogenic fungi;
Beauvaria bassiana and the entomopathogenic nematodes; Steinernema
feltiae are 1000 ppm, 40000 ppm and 5000 infective juveniles,
respectively.
Monitoring insecticidal resistance in the field colony of B.
zonata flies collected from different Governorates to Malathion
toxicity by using discriminating concentration technique:
Four strains were selected from natural populations; i. e. fields
located in Menoufia, Qalubia, Behira, and Ismailia Governorates to
determine the resistance levels of B. zonata flies to the recommended
organophosphorus insecticide, Malathion. Moreover, the effect of the
LC50 of the tested toxicants used in this study on some biotic potential in
the flies emerged from the prepupae was implemented. The laboratory
strain was used as a baseline in insecticidal toxicity and biochemical
assays.
SUMMARY
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The response of the peach fruit fly, B. zonata flies collected from
different Governorates to discriminating concentration of Malathion
(LC99) was investigated. Data revealed that Ismailia field strain exhibited
the highest resistance value to Malathion toxicity followed by Behira
field strain. On the hand, Menoufia and Qalubia field colony strains
showed the lowest resistance value to Malathion.
3. Biochemical studies on the peach fruit fly, B. zonata:
Hydrolyzing enzymes activity( alkaline and acid phophatases, nonspecific
esterases and acetylcholinesterase) glutathione S-transferase,
mixed function oxidases and total protein content were determined in
flies of B. zonata collected from four Governorates. The obtained results
were compared with the baseline laboratory strain that was not subjected
to any insecticides.
The results indicated that B. zonata flies of the different field strains
showed remarked higher levels of the enzymatic activity that were
mentioned previously than the laboratory strain. The flies of B. zonata
selected from Ismailia Governorate showed the highest levels of the
hydrolases, and glutathione S-transferase activity as well as total protein
content. On the other hand, flies collected from Qalubia horticultural
orchards exhibited the lowest levels of hydrolases, mixed function
oxidases, Glutathione S-transferase activity and total protein contents. It
could be concluded that the enzymatic activity as well as the total protein
content play an important role in resistance of the B. zonata flies to
Malathion toxicity, where there was positive correlation between
resistance levels in the different field strains and the levels of the
enzymatic activity in these strains.
SUMMARY
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4. Development of resistance in the flies of the peach fruit fly, B.
zonata to the toxic action of Malathion:
The pressure of Malathion against the flies of B. zonata showed an
increase of 20.05 folds than the laboratory strain after six generations.
Results revealed that, there was a correlation between the response of the
different generations and selection pressure with Malathion. The
LC50values increased by succession of generations irrespective of the
tested toxicant by using LC20 of Malathion as compared with the
laboratory strain.
Tolerance in the selected adults to the toxicant was noticed in the
first four generations, i.e. G1 –G4, whereas G5 and G6 exhibited resistance
in the selected adults.
5. Effect of the six toxicants on the biotic potential of B. zonata:
It is important to clarify the possible relationship between adult
emerged by prior treatment of the prepupae with the LC50 values of the
six toxicants used in this study and the reproductive potency of these
adults.
5.1. Effect on pre-and oviposition periods:
It is quite clear from the obtained results that there is a significant
increase in the pre-oviposition periods at all toxicants as compared to the
control group. The lowest pre-oviposition period was observed with the
tested organophosphorus insecticides in case of copulations between
untreated males and treated females as compared with the other toxicants
. On the other hand, lower periods of oviposition were recorded in case of
copulations between flies emerged from prepupae treated with the LC50
values of the organophosphorus insecticides than those emerged from
SUMMARY
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treatment with LC50 values of the miscellaneous toxicant, Abamectin,
entomopathogenic fungi and entomopathogenic Nematodes.
The lowest periods of oviposition were attained in case of
copulations between treated males with treated females. There is a
significant decrease in the oviposition periods at all tested toxicants as
compared with the correspondent untreated males with untreated females.
5.2. Effect on fecundity (the number of eggs laid/ female):
It is quite clear from the obtained results that there is highly
significant decrease in the number of eggs laid/ female at all toxicants as
compared with the control group. The lowest number of eggs deposited
per female was attained for the tested organophosphorus insecticides
(Malathion, Dimethoate and Actellic) in case of copulations between
treated males and treated females. Maximum fecundity was noticed in
the other copulations between treated males and untreated females
associated to the organophosphorus insecticides. Moderate effect of the
LC50valuess of the six tested toxicants on the number of eggs laid/ female
was attained in case of the copulation between treated females and
untreated males. The lowest fecundity was observed in case of treatments
with Malathion and the highest fecundity was observed in case of
treatments with Nematodes.
5.3. Effect on fertility (percent of hatchability):
It is clear that the fertility of eggs (percent of hatchability) deposited
by females emerged from the treatments of prepupae of B. zonata with
the LC50 values of the six toxicants in this study showed a significant
decrease in all tests as compared with the untreated flies. It is obvious that
Malathion and Dimethoate have pronounced latent effect on the egg
viability. The lowest latent effect of the six toxicants was attained when
the treated females mated with untreated males.
SUMMARY
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The highest latent effect of the six tested toxicants on the viability of
eggs deposited by females of B. zonata emerged from treated prepupae
was attained when the treated females mated with treated males followed
by the copulation between untreated females and treated males, whereas
the lowest latent effect was observed when treated females mated with
untreated males.
5.4. Effect on sterility:
It was obvious that, the highest sterility value was noticed when the
copulations occurred between males and females emerged from the
treatments of prepupae of B. zonata with the LC50 values of all toxicants
with the exception of Bio-power. On the other hand, the lowest sterility
percentages were attained in case of mating between treated females with
untreated males. Whereas the copulation between untreated females with
treated males occupied the middle situation among the two copulations
that mentioned previously. The decline of sterility may be related to
sperm ability of treated males as well as inhibition of ovarian
development of treated females of the peach fruit fly, B. zonata.