New pesticides based on natural products are urgently needed, in consideration of their environmental care and lower collateral effects. Neem oil, the main product obtained from Azadiractha indica A. Juss, commonly known as neem tree, is mainly used in medical devices, cosmetics and soaps, as well as important insecticide. Manufacturing of neem oil first includes the collection of the neem seeds as raw material used for the extraction. Neem cake is the waste by-product remaining after extraction processes. The quality of the oil, as that of the cake, strictly depends from the quality of seeds as well as from the type of extraction processes used, which strongly influences the chemical composition of the product. Currently, the different types of commercial neem cake on the market are roughly identified as oiled and deoiled cake, but several other differences can be detected. The differences are relevant and must be determined, to obtain the necessary correlation between chemical constitution and larvicidal activities. Six different batches of neem cake, marketed by several Indian and European companies, were analyzed by HPLC and HPTLC, and their fingerprints compared, obtaining information about the different compositions, focusing in particular on nortriterpenes, considered as the main active components of neem oil. Therefore, the chemical composition of each cake was connected with the biological activitiy, i.e., the effects of the extracts of the six neem cakes were tested on eggs and larvae of Aedes albopictus (Stegomyia albopicta) (Diptera: Culicidae), commonly known as Asian tiger mosquito. The results confirmed the previously reported larvicide effects of neem cake that, however, can now be related to the chemical composition, in particular with nortriterpenes, allowing in that way to discriminate between the quality of the various marketed products, as potential domestic insecticides.
Micro vs. macro competing for lifeMicroorganims are difficult to find and to kill, because they are in enormous number and everywhere. For instance, in our body we can count more procariotic than eucariotic cells. Fortunately, most of them are useful friends, but others can be very dangerous and destructives. Actually, microorganisms are liable of major plagues affecting humans. These invisible our competitors act infections by complicated mechanisms, often involving other creatures. Mosquitos are the favorite partners as major vector of transmission. Therefore, mosquitos are co-responsible of malaria, dengue fever, yellow fever, filariasis, schistosomiasis, Japanese encephalitis, Chagas morbus, hemorrhagic fever, arbovirosis, as well as of several minor pathologies, such as systemic allergic and inflammatory reactions and dolorous bites. Although in developed countries the impact of these pathologies is nowadays restricted or absent, and main causes of death are related to physiological aspects (cancer, hearth and www.intechopen.com Insecticides -Advances in Integrated Pest Management 412 coronary failures, ecc.), in the remaining predominant part of the world, the alert is always the same and means infection by injure or by bite. Practically all mankind living in ordinary conditions is continuously exposed to one or more mosquito-borne or connected diseases and suffer in different degrees the effects of the mosquitos attack. Only dengue worldwide threatens the health of around 2.5 billion people, and figures for malaria are surely worst. Malaria infects more than 500 million humans each year. About 90% of cases occur in Africa, including those of malaria-related deaths, but only in India 15 million cases and 20,000 deaths are estimated annually by WHO. However, as all living beings, also microorganisms have their own Achilles heel. Their movement capacity is very limited, therefore they use animals as vectors for efficiently diffusing in every habitats. Usually, they change to adapt to the host, accumulating therein and becoming vulnerable. Therefore, the option seems to be simple: kill the vector and kill the microorganism. Fighting the vectorSeveral strategies have been proposed against microorganism/mosquito based diseases in order to control or at least limit mosquitos invasion, mainly based on three types of action: direct, environmental, indirect. Direct methods use as target the adults, whereas indirect methods are mainly focused on effects on mosquito development, including controls of larvae by hormones or other growth regulators. Environmental methods are based on change in the habitat of the insect and display severe collateral effects on other organisms. So far, mainly synthetic insecticides have been produced and used, in large quantities and types. Initial euphoria for the resolving effects has been punctually followed by negative drawback. Chemical pesticides resulted non-selective, that means harmful and toxic to other organisms including humans, plus the cause of a series of unexpected and dur...
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