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Effective biological control for pests such as non-native fire ants : A virus present in low levels in the U.S. is effective at managing populations of non-native fire ants, according to research. Although solely focused on the red imported fire ant, Solenopsis invicta, the study published in the Journal of Invertebrate Pathology shows promise for gardeners, land managers, and the public looking to manage fire ants without the use of hazardous chemical insecticides.
As climate change and global trade facilitate the spread of dangerous non-native species, there is a strong need for new and cutting-edge approaches that target these pests without significant harm to public health or the surrounding environment.
Pests are a constant risk to farms.
By using data to better understand pest risks and building vulnerabilities we are able to develop innovative products to help keep farms safe
Among all the viruses that have been identified by humans, b-oculoviruses have been more useful than other species. The family of baculoviruses (Baculoviridae) is of special importance because they are extremely specific in causing pathogenicity in insects.
Fighting plant pests has long been one of the important concerns of agricultural producers. In the past decades, chemical control with pesticides has always been considered as the most effective method of fighting, and this is while the destructive environmental effects, morality in natural balance, the destruction of natural enemies, and ultimately the resistance of pests to chemical poisons have caused other Pest control methods, including biological ones, should be given serious attention.
Microbial insecticides include fungal, bacterial and viral insecticides, which are sold in various commercial forms in the form of powder, wp and liquid. The use of biological pesticides in the world is only 1% of the consumption share compared to other pesticides. So far, viral diseases have been reported and described in more than 500 species of pests. Pathogenic baculoviruses in insects are completely safe for humans and animals, and there are no reports of causing disease in humans, animals, or even birds that have fed on infected larvae.
Although viruses are not widely known and available, several insect viruses have been developed and documented to be used as insecticides. Most of them are for forest pest control.
Although not economically available, they are produced and used by the US Forest Service.
Forest pests are good targets for viral pathogens because the continuity of the forest environment helps the pathogen cycle (transmission from one generation to the next).
The forest canopy also helps to protect virus particles from being destroyed by ultraviolet rays.
Many species of insects are called pests because they mostly cause damage to humans as competitors for the food that humans grow. Many of these pests are susceptible to viral infections, which have been reported in more than 800 species of insects and mites. Therefore, these viruses can be used as biological control agents. Some of these viruses cause the destruction of harmful insects and some others cause the death of beneficial insects. Considering the importance that insects have in the ecosystem, it is very important to identify pathogenic viruses in them.
Insect viruses may directly infect insects or be transmitted by other insects. Although there is a high diversity of insect viruses, only a few are seen in insect populations, such as:
Ascoviruses, Baculoviruses, Densoviruses, Entomopoxviruses, Hytrosaviruses, Iridoviruses, Nudiviruses, Polydnaviruses, Dicistroviruses, Iflaviruses, Nodaviruses, Tetraviruses and Cypoviruses, and among these only a number A few, especially baculoviruses, have shown the potential to be used as control agents.
Apart from baculovirus and cytoplasmic polyhedrosis virus groups, they have biological properties that should lead to their successful use as microbial control agents in integrated pest management programs. This virus infects the larval stages of many lepidopterous and hymenopterous pests and produces a chronic and fatal infection and the release of large amounts of relatively stable infectious mass bodies (IBS).
An important part of the work is the development of new strategies to control pest insects using baculoviruses. This issue requires testing the virus in different hosts, which should be developed, optimized and used in cell culture, bioassays with living insects in the laboratory and in field experiments.
Due to the declining population of some insect species and also because they are highly pathogenic to insects, it has made them an ideal candidate for pest control.
In Canada, 3 types and 7 types of viral insecticides have been registered in the United States, of which 8 types are from the npv group and two types are from the gv group. In Brazil, corn and bean leafworm control has been taken into consideration by NPV and has been extended and exported to neighboring countries. The isolated Gv phthorimae operculella has been used against potato tuber worm and has been exported to other neighboring countries (South America).
The use of baculoviruses has been considered as one of the IPM programs. In Thailand, significant progress has been made on S.exiguaNPV, Helicovera armigera NPV.
In Malaysia, LITURANPV isolation has been reported on acacia. In China in the 1960s, the PIERIS RAPA GV isolate was reported and then produced and evaluated. So far, three isolates of GV and 10 isolates of NPV have been reported and evaluated in China on the pests of fruit trees and agricultural plants.
Pathological studies of silkworms have been of interest in Japan for many years. In this country, 5 types of NPV on pests and 2 types of GV virus isolates from Adoxophys sp homona magnanima tea pests have also been reported and evaluated.
In Japan, a viral insecticide from the cpv group has been registered on d.spectabilis. Most of the studies conducted in Egypt were on baculovirus isolates of cotton leaf-eating larvae
They have good durability in the soil.
They act exclusively.
They are safe for humans and animals.
The pathogen can spread throughout the insect’s body in this way (especially when the spread and use of chemical insecticides is limited.
In the countries of Southeast Asia, due to favorable climatic conditions and extensive and dense cultivation of fruit and fiber crops, it has caused the diversity of pests and especially in the 1980s, it has caused the indiscriminate use of pesticides.
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If registered viral insecticides or registered products become more available, their effective use depends on consumers remembering the following basic facts:
Most viruses are host-specific and effective only in early stages of the species.
Consumers should be sure that they have chosen the correct pathogen and pest.
Viral particles are killed by ultraviolet rays, which increase their effect in the evenings or on cloudy days.
Insects are infected by eating baculoviruses. Viruses of this family enter the hemolymph after entering the larva’s body. In the midgut, the protein coat of the virus is dissolved and the pathogenic virions are released. Virions attack midgut cells and their nuclei and reproduce there. Then they come to the surface of the midgut cells and enter the hemolymph of the insect again.
Different viral products are available under different trade names. How to use these products may differ depending on the type of virus and target pest. For the best result, it is better to completely cover the surface of the leaves with the desired product. Also, because the time of adding the product is very important in the field, tracking adult insects to determine the time of egg laying and hatching is effective in better control.
Viruses of insect-borne diseases are among the natural and harmless factors for the environment and effective in pest control. Isolation, identification, reproduction
These factors are very important. Given that the proliferation of viruses is related to the environment
Dedicated cultivation, including the challenges of producing and multiplying insect pathogenic viruses
you count Currently, most of the countries that use viral insecticides use pathogen host larvae to reproduce the virus. Researches in
Cell culture of the mentioned viruses has started in developed countries
Cost-effectiveness of production is one of the effective factors in the production of insect viruses.
The production of viruses, the possibility of rearing host larvae, is simply possible, it is completely economical and cost-effective. Due to the availability of cell culture technology , it is possible to produce and evaluate economically, the production of insect pathogenic viruses.
Another limitation The use of viral insecticides is the speed of host virus reproduction. Advanced countries have increased the speed of virus effect by using genetic engineering techniques. Another limitation of using viral insecticides in nature is the sensitivity of viruses to ultraviolet (UV) light. Currently, despite the use of uv protective materials in the formulation of viral insecticides, the durability of the virus in front of sunlight is short.
Viruses have different functions in terms of pathogenicity and lethality in different insects, and one of the reasons for this difference is their resistance in the stomach of insects. Naked viruses (without coating) usually do not last long in the stomach of insects, but viruses that have a coating are more resistant. To cause disease in an insect, the virus must enter the stomach, pass through the stomach wall and enter the blood. Then it enters the sensitive blood cells and passes through its cytoplasm and finally enters the cell nucleus and causes disturbances.
During this disorder, the virus may be destroyed by blood cells or its pathogenic power may be limited. Viruses that enter the cell nucleus are more specific than viruses that replicate in the cytoplasm. The time required to kill the target insect depends on various factors such as the concentration of the virus, the life stage of the host insect, etc. One of the most important pathogenic viruses in insects is the NPV polynuclear virus with the brand names Elcar and VHZ, which is very effective in controlling the Heliotis worm and a number of other pests and is still used today.
The most successful microbial insect control project involved the control of the wasp Gilipinia hercynia using the NPV virus, which was implemented in Canada.
The said bee had caused the destruction of 73% of the white pine trees and 43% of the black pine trees in a large area of more than 2000 square miles.
Viruses are used in insect control in two ways:
A: The virus is introduced into a part of the pest population, and after it is introduced into the pest population, it spreads in different ways.
B: Spraying foliar spray or spreading the virus on insects, in this method, care should be taken that the time of spraying the virus coincides with the early stages of the insect larvae.