الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Mosquitoes is considered the vector of malaria, dengue fever, lymphatic flariasis, rift valley fever, Japanese encephalitis, yellow fever, dengue haemorrhagic fever, viral encephalitis, and Zika cause extensive human morbidity and mortality and are a major economic burden within disease-endemic countries.
The aim of this study was to investigate the mosquitocidal activity of the officially recommended mosquitocides and promising natural occurring compounds against mosquitoes, also to convert the most active compounds to new applicable formulations to control mosquitoes, in addition to determine the mosquitocidal activity of the new formulated mosquitocides against mosquitoes.
To accomplish this study:-
Different eco-friendly controlled release formulations were prepared then selected one of them to load the recommended larvicides (malathion, temephos, and spinosad).
The description of these CRFs was done using FT-IR, SEM, Swelling properties, and size measurement for loaded and some of unloaded formulations.
Eco-friendly formulation for adults (biologically active monoterpenes loaded on paper discs and wax) were prepared.
The larvicides content in the controlled release capsules was determined.
The content of larvicides release was determined daily in running and stagnant water until nondetectable reading.
Larval bioassay for technical and formulated recommended larvicides (malathion, temephos, and spinosad) was done against Cx. pipiens larvae.
Larval bioassay for loaded capsules was done against Cx. pipiens larvae in running and stagnant water until a negligible mortality was obtained.
Fumigant bioassay of monoterpenes loaded on paper discs and wax was done against female adults of Cx. pipiens.
Monoterpenes were assayed against female adult Cx.
pipiens by residual method.
Specific activities of extracted acetylcholinesterase (AChE), carboxylesterase (CaE), and glutathion-S-transferase (GST) were determined in surviving larvae treated with LC50 of each technical and formulated larvicides after 24 h of exposing.
The obtained results can be summarized as follows:
1. Preparation of biodegradable controlled release larval formulations
1.1. Preparation of chitosan/sodium alginate/gelatin capsules
Twelve capsule products were prepared with constant concentration of chitosan and sodium alginate (1% each) in combination with three different concentrations of gelatin (2.5, 5, and 10%) and four different concentrations of glutaraldehyde (0.25, 0.50, 1.0, and 2.0%). The data showed that the increasing in gelatin concentration led to an increase in the weight of the yielded capsules
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after drying. However, in comparison with the different percentages of gelatin in number capsules per gram, it can be noticed that close differences between the concentrations of 2.5% (GI) and 5% (GII). While, 10% gelatin (GIII) have the lowest number of capsules per gram. The products with 2.5% gelatin have the lowest capsule diameter (970±38.66, 950±22.80, 880±35.77, and 860±70.14 μm for CP1, CP2, CP3, and CP4, respectively). While, the highest diameter was found with 10% gelatin (1470±96.54, 1150±10.95, 1120±74.02, and 970±12.64 μm for CP 9, CP 10, CP 11, and CP 12, respectively). Morever, glutaraldehyde play an important role in the preparation of this type of capsules, i.e. increasing its concentration led to gradually decrease in capsule diameter in all groups.
1.2. Preparation of chitosan/sodium alginate/gelatin capsules loaded with the three tested chemical recommended larvicides
The prepared capsules loaded with 16.05% malathion, 7.35% temephos and 18.85% spinosad were determined by UV/Visible spectrophotometer at λmax 203, 201, and 200 nm, respectively. It can be noticed that the unloaded capsules are higher in diameter (1004±108 μm) than the loaded with malathion, temephos, and spinosad (931.8±81.2, 954.55±97.61, 770.91±52.62 μm, respectively) which give 820, 2170, 2650, and 3240 capsule per gram, respectively.
2. Preparation of biologically active monoterpenes loaded on paper discs
The concentration of monoterpenes (8.94%) in PD4 (camphor, menthone, carvone, fenchone, and citronella oil) formulation was the highest concentration followed by PD5 (geraniol, thymol, menthol, and citronella oil) (7.84%). On the contrary, the concentration of monoterpenes in PD7 (citronella oil alone) formulation was the least (5.132%).
3. Specteral analysis of tested larvicides
The maximum wavelength appeared at 203 nm for malathion , at 201 nm for temephos, and at 200 nm for spinosad.
4. Estimation of larvicide content in the controlled release capsules
The capsules were loaded with 16.051% malathion, 7.353% temephos, and 18.854% spinosad as determined by UV /Visible spectrophotometer at the maximum wavelength.
5. Determination of the content of the larvicides released in running and stagnant water at different time intervals using UV/ Visible spectrophotometric method
Malathion released (mg /100 mL water) from prepared capsules in the running and stagnant water daily continued upto 17 and 30 days, respectively. While, temephos released continued upto 30 and 40 days in the running and stagnant water, respectively. Likewise, the released spinosad continued upto 24 and 47 days in the running and stagnant water, respectively.
6. Larvicidal activity of technical and formulated recommended larvicides
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The results of technical larvicides bioassay against the third instar larvae of Cx. pipiens showed clear difference between the tested compounds .Temephos has the highest larvicidal effect (LC50 = 11.6 ppb) followed by spinosad (LC50= 75.23 ppb), while malathion was the least toxic one (LC50 = 1108 ppb). The same trend was followed after 48 h. However, the results of formulated larvicides bioassay showed that, spinosad has the highest larvicidal effect (LC50 = 8 ppb) followed by temephos (LC50= 228 ppb), while the malathion was the least toxic one (LC50 = 4407 ppb). The same trend was followed after 48 h.
7. Larvicidal activity of controlled release capsules
The larvicidal activity of controlled released malathion capsules according to the larval mortality for different weights of capsules (50, 20, 10, 5 mg) was recorded. All capsule doses in running water experiment reached to zero mortality after 20 days in the running water experiment. Nevertheless, 50 mg and 20 mg capsules showed zero mortality after 27 and 24 days, respectively in the stagnant water experiment, however, 10 and 5 mg capsules showed the zero mortality after 20 and 16 days, respectively. While in the case of temephos, in the running water experiment, mortality percent stand still at 100% up to 92 day in the experiment for 50 mg capsules, however, in stagnant water still achieved 100% mortality up to 120 day. Although, the released spinosad from 50 mg of capsules still achieved 100% mortality up to the seventh month in the stagnant water experiment.
8. Fumigant knocdown bioassay of monoterpenes loaded on paper discs against female adults
The mixture of ketone monoterpenes (PD1) recorded the lowest median time (KT50) which was calculated as 17.2 min followed by mixture of ketone monoterpenes and citronella oil (PD4) which was calculated as 20.8 min. The mixture of alkene monoterpenes (PD3) recorded knock-down median time at 27.4 min, followed by the paper disc impregnated with citronella oil alone (PD7) at 28.7 min and the mixture of alkene monoterpenes with citronella oil together (PD6) at 33.2 min. from these results the mixture of monoterpenes without adding of citronella oil was more active than the mixture of monoterpenes with adding of citronella against Cx. pipiens. Mixing the citronella oil with previous tested groups of monoterpenes delayed its knock-down time against Cx. pipiens. The citronella oil alone showed moderate effect.
9. Fumigant knockdown bioassay of monoterpenes incorporated on wax against female adult Cx. pipiens.
These results proved that adding citronella oil to mixures of the monoterpenes decreased their activity to neglected knockdown effect (KT50 ˃ 120 min). The ketone monoterpenes incorporated into wax gave the highest activity against mosquitoes.
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10. Residual knockdown activity of monoterpenes against female adult of Cx. Pipiens
Among the three monoterpenes, menthol was the most effective compound which gave KT50 of 11.66, 3.73, and 2.57 min at 10, 20, and 40 μg /cm2, respectively. However, camphor and camphene showed knock-down effect at the highest concentration only (40 μg /cm2) with KT50 of 25.49 and 49.84 min, respectively. Deltamethrin showed KT50 19.48, 12.02, 5.54, and 1.94 min at 0.05, 0.1, 0.5, and 5 μg /cm2 respectively. It can be noticed that the deltamethrin still the most active against adult compared to the tested monoterpenes.
11. Biochemical studies
It can be noticed that the technical malathion caused the highest inhibition percentage in CaE (100%) then AChE (93.78%) and GST (86.10%). In addition, capsules loaded with temephos caused the highest inhibition percentage in AChE (83.91%) then CaE (80.31%) and GST (53.23%). Likewise technical spinosad caused the highest inhibition percentage in AChE (87.36%) then CaE (82.12%) and GST (79.31%). In the case of formulated form of the same mosquitocides, formulated malathion caused the highest inhibition percentage in AChE (87.25%) then GST (64.80%) and CaE (60%). Formulated temephos caused inhibition percentage in AChE (77.23%), and CaE (98%). Likewise, formulated spinosad which caused inhibition percentage 79.86% for CaE, 72% for GST, and 48.99% for AChE.