Technical Field:

This invention is related to public health pesticide. Specifically the control of the prevalence of infectious diseases transmission vectors from mosquitoes species.

Background Art:

The problem of infectious diseases which transmitted via mosquitoes attracted the great attention all over the world. Malaria, filaria, dengue fever, rift valley fever, chikungunya and zika fever are the most common infectious disease transmitted by mosquitoes like Anopheles , Culex and Aedes genera.

Malaria as an example of infectious diseases is an extremely serious disease threatening more than 3.2 billion people in more than 107 countries. It remains one the major causes of poverty and underdevelopment, and one of the main obstacles in front of economic growth. And despite the World Health Organization (WHO) efforts since the 1950s to eradicate this disease, it still results in massive economic and human losses, especially in sub Saharan Africa and some rural areas of Asia and Latin America. Each year, more than 350 million people get this disease and more than one million people die from it ^{( 1 )}

Rift Valley Fever (RVF) is a viral pathogen that affects primarily domestic livestock, but can be passed to human causing fever. It is spread by infected mosquitoes, and among the principal mosquito vectors are Aedes caspius or Culex spp. The disease is caused by the RVF virus, a member of the genus Phlebovirus (family Bunyaviridae). It was first reported among livestock in Kenya around 1915, but the virus was not isolated until 1931. In Egypt, several million people were infected and thousands died during a violent epidemic attack in 1977-78, probably caused by infected domestic animals exported from Sudan, which resulted in a large outbreak of RVF among animals and humans. Approximately 1% of human sufferers die from the disease, while in livestock the mortality level is significantly higher ⁽²⁾

The widespread use of insecticides to control these vectors has disturbed the parasitoid and predator populations and also led to an increase in the development of resistance to most of the insecticides used in conventional programs ⁽³ ' ⁴⁾ . This problem can be solved by using environmentally safer compounds such as photosensitizers which have minimal risk on mammals.

The photosensitization of the natural system by porphyrins presents specific advantageous features such as low environmental impact ⁽⁵⁾ and the absence of mutagenic action towards biological targets ⁽⁶⁾ .

Porphyrins appear particularly promising photoinsecticides because they absorb essentially all the wavelengths of the solar spectrum. Hence, they can undergo a very efficient photoexciation by sunlight producing a high quantum yield of singlet oxygen, a cytotoxic oxygen derivative ⁽⁷⁾ .

The use of photochemical processes as a tool to control the population of several types of insects has been examined in both laboratory and field studies ⁽⁸ ' ⁹⁾ . Hematoporphyrin (HP) activities were tested in dipterous larvae ( ¹⁰ ' ^{n )} reported an extended series of tests with mosquito larvae under fluorescent light and at rose Bengal level of 1 to 20 ppm. They found that the early instars of Aedes larvae were more susceptible than the later instars.

Photopesticides:

Although light has been known to enhance certain toxic reactions in biological systems since 1888, the principle was not exploited until after 1970 to any great extent. The greatest concentration of effort has been in the study of photodynamically active dyes, primarily the halogenated fluorescein series, as prospective insecticides. More recently, compounds of plant origin have been isolated, identified, and studied as phototoxins against a wide range of pests, including insects, fungi, and weeds. The main classes studied to this time are the furanocoumarins, thiophenes, acetylenes, extended quinones, and chlorophyll (A) intermediates popularized as laser herbicides^ ² " ¹ .

Many trials were carried out using different larvaecides to reduce the effective concentration of the old generation of photosensitizers ^(13"16) .

In spite to the high effmcy and environmental friendliness of this class of pesticides, they are not applied in wide range due to high cost and lack on optimum methods of cost effective mass production.

This invention solves this problem and presents the long awaited answer for the puzzling dilemma. It introduces a new method that combines both the effectiveness and efficiency with the highest levels of human safety and environmental friendliness and cost effective mass production. The new method is designed to the indoors and outdoors infectious diseases mosquito vectors control by using fast water surface spreading liquid formula of naturally extracted photosensitive compounds as environmentally friendly photolarvicide to control the larvae of Anopheles, Culex and Aedes.

Disclosure of Invention:

This invention introduces a novel formula for the control of noxious insects. It was the pioneer that was concerned with the synergistic effect of photoactive compounds carried by good dispersant material on the infectious diseases transmission vectors like mosquitoes in larvae and pupae stages.

Methodology:

Preparation of SAFE Plus:

A semi-industrial mass production of SAFE Plus was designed to evaluate the best cost effective and efficient method of SAFE Plus production. The samples of each production trial were applied on different mosquitos' species to explore the efficiency of control and residual effect.

The trial of production includes the trial and error way using different weight percentages of the different SAFE Plus components (photosensitive material, carrier material from simethicone category, suitable surfactant and organic solvent) as a function of efficiency and cost. Study the efficiency of SAFE Plus:

All experiments of efficiency were carried out on different species of mosquitos' larvae {Anopheles, Culex and Aedes) field strains. Indoor and outdoor efficiency evaluation was carried out under the same experimental conditions to explore the photosensitization efficiency in natural and artificial light exposure as well as the physical effect of carrier material to disrupt the mosquito larvae to have enough time of breathing through the water surface in dark conditions of light unexposed mosquitoes breeding sites.

Data Analysis

Data was assayed by analysis of variance (ANOVA), with the means of separation using Duncan's Multiple Range criterion (PO.05).

Brief Description of tables:

Table 1,

The data of table one show the percentage of survival of mosquitos' larvae in different indoor conditions. Ten tank of fresh water were used as treated experimental tanks and five tanks act as control experimental tanks. All tanks were kept in indoor conditions mimicking to fresh water storage container in homes which are ideal environments for mosquitoes (like Aedes sp.) breeding. Each control and treatment tank was supplied with 200 larvae. The experiment started by adding 0.5 ml/m ^" of SAFE plus on the water surface of treatment tanks. The experiment was followed up to 38 days after treatment onset. When the percentage of larvae survival reaches to zero we added more 200 larvae. The sign "+" refer to the day of new larvae addition in each treatment.

The table reflected the high efficiency of SAFE plus on reduction of mosqutioes larvae and the duration of residual effect which exceed five weeks. In all days no pupae were developed which means the lifecycle was stopped and no adult were emergent from these breeding sites.

In control experiment (breeding tanks without treatment) there is no significant mortality and had only four time of larvae addition to the breeding tanks due to change of the larvae to pupae and adult emergence.

Table 2:

The data of table two show the percentage of survival of mosquitos' larvae in different outdoor conditions. Ten natural breeding site were used for treatment and five breeding sites used as control. The experiment started by adding 0.5 ml/m of SAFE plus on the water surface of treatment breeding site. The experiment was followed up to five weeks after treatment onset. When the percentage of larvae survival reaches to zero we added more 300 larvae as a new generation to study the residual effect in the natural breeding sites. The sign "+" refer to the day of new larvae addition in each treatment and control site.

This table reflected the high efficiency of SAFE plus on reduction of mosquitoes' larvae and the duration of residual effect which exceed five weeks. In all days no pupae were developed which means the lifecycle was stopped and no adult were emergent from these breeding sites.

In control experiment (breeding sites without treatment) there is no significant mortality and had only six times of larvae addition to the breeding sites when the larvae survival percentage reach to average 50 % due to change of the larvae stage to pupae stage and adult emergence.

Table 3:

The data of table three show the percentage of survival of mosquitos' pupae in different indoor conditions. Ten tank of fresh water were used as treated experimental tanks and five tanks act as control experimental tanks. All tanks were kept in indoor conditions mimicking to fresh water storage container in homes which are ideal environment for mosquitoes breeding. Each control and treatment tank was supplied with 100 pupae. The experiment started by adding 0.5 ml/m ² of SAFE plus on the water surface of treatment tanks. The experiment was followed up to 38 days after treatment onset. When the percentage of larvae survival reaches to zero we added more 100 pupae. The sign "+" refer to the day of the new pupae addition in each treatment.

The table reflected the high efficiency of SAFE plus on reduction of mosquitoes' pupae and the duration of residual effect which exceed five weeks. In all days no adult were developed which means the lifecycle was stopped and no adult were emergent from these breeding sites.

In control experiment (breeding tanks without treatment) there is no significant pupae mortality and had nine times of pupae addition to the breeding tanks due to adult emergence.

Table 4:

The data of table four show the percentage of survival of mosquitos' pupae in different outdoor conditions. Ten natural breeding site were used as treatment sites and five breeding sites used as control sites. The experiment started by adding 0.5 ml/m ² of SAFE plus on the water surface of treatment breeding site. The experiment was followed up to five weeks after treatment onset. When the percentage of pupae survival reaches to zero we added more 100 pupae as a new generation to study the residual effect in the natural breeding sites. The sign "+" refer to the day of new pupae addition in each treatment and control site.

This table investigated the high efficiency of SAFE plus on reduction of mosquitoes' pupae and the duration of residual effect which exceed five weeks. In all days no adult emergence were developed which means the lifecycle was stopped at this stage also.

In control experiment (breeding sites without treatment) there is no significant mortality and had only five times addition to the breeding sites when the pupae survival percentage reach to average 50 % due to adult emergence. Table 1:

Table 2:

Table 3:

Table4:

Day of Percentage of Pupae survival (outdoor evaluation)

monitoring Treatment Control

% of Adding % of Adult % of Adding pupae % of Adult survival pupae emergence survival emergence

Dl 100 0 100 0

D2 0 + 0 100 0

D3 10 0 95 5

D4 0 + 0 80 20

D5 0 + 0 60 40

D6 10 0 55 + 45

D7 0 + 0 100 0

D8 15 0 95 5

D9 5 0 80 20

D10 0 + 0 75 25

Dll 10 0 65 35

D12 0 + 0 50 + 50

D13 10 0 100 0

D14 10 0 100 0

D15 0 + 0 95 5

D16 30 0 90 10

D17 20 0 90 10

D18 10 0 85 15

D19 0 + 0 77 23

D20 20 0 65 35

D21 20 0 55 + 45

D22 5 0 100 0

D23 0 + 0 100 0

D24 50 0 90 10

D25 30 0 85 15

D26 30 0 85 15

D27 10 0 75 25

D28 0 + 0 60 40

D29 30 0 55 + 45

D30 25 0 100 0

D31 10 0 95 5

D32 10 0 90 10

D33 5 0 80 20

D34 5 0 75 25

D35 0 + 0 66 34

D36 40 0 60 40

D37 28 0 50 + 50

D38 20 0 100 0 References:

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