Do beneficial insects exist?
Technical note of edition 8 on Do beneficial insects exist?, with a focus on diagnosis, prevention and criteria applicable to professional pest management.
The effect of urbanization and the creation of private neighborhoods encourages populations to move closer and closer to the places where agricultural production systems are located, this brings with it a greater number of annoying insects and vectors of diseases such as certain dipterans that are frequent fauna of them. Production systemsFaculty of Cs. Agrs. National University of Lomas de Zamora.
Agricultural production, being close to the urban area, increasingly complicates the management of its waste. This is associated with the proliferation of large quantities of insect pests such as flies, since excrement is the ideal substrate for the development of pests where they feed, reproduce and carry out their cycle. Among them we can find the house fly, house fly, etc. The life cycle develops in animal droppings. Degradation is a slow process in which
the drying action of the sun, rain, decomposition by fungi and bacteria, and consumption by dipteran and termite larvae. The action of some individuals such as coprophagous beetles, which break up, distribute and bury the excrement, extraordinarily accelerates this process, while fertilizing the soil. The dung beetles use the excrement to feed and raise their offspring, making the breeding chambers with soil and manure and then burying it almost one meter away, transforming the excrement into a place not suitable for the development of flies. There are some species in which the parents take care of the breeding chambers until the adult insects emerge. They have a very low reproduction rate, one or two eggs, and that is why they are so sensitive to changes in the environment. However, without their action, the accumulation of manure would be unsustainable for ecosystems, therefore it is essential to learn to recognize them, and thus be able to take care of them. The color of the beetles varies from black to metallic green, they have the first pair of legs that are adapted to digging and extracting soil, and a characteristic expansion in their head which allows them to dig the ground and thus be able to make underground galleries, where later, once extracted and placed on the surface, they will fill with excrement that will serve to feed themselves as well as their offspring. It has been estimated that coprophages bury 1.5 tons of excrement per hectare and year. In the province of Buenos Aires, a large number of dung beetles have been found, with the ability to disintegrate and bury excrement. The presence of several species was determined such as Gromphas lacordarei, Ontherus sulcator and Onthophagus hirculus among others. Although the biocontrol activity of these beetles is similar, it should be noted that the size of G. lacordarei makes it more effective, since the volume of excrement it buries to feed and build breeding chambers is greater. With an abundance of between 10 to 20 beetles, the fecal matter is completely buried before
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term of larval development that Diptera need. Therefore, these types of insects significantly reduce the possibilities of development.
One of the most characteristic beetles of the province of Buenos Aires is Gromphas lacordairei: The volume of excrement incorporated by this beetle
It is in the order of 8 to 10 gr. per day, (Cabrera Walsh G., et al., 1997), which gives a complete incorporation of it in 7 days by the action produced by 10 to 20 beetles. This period of time is not enough for the flies to complete their development. This incorporation is produced by the work of the male and female; they bury significant amounts of excrement that is used for the development of the larvae and the feeding of the adults.
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Not only does the consumption of the beetles' excrement harm the flies, but also during the feeding process, as it produces aeration and drying of the fecal matter, which prevents the breeding of the flies. It is not necessary for the beetles to consume all of it because when they begin to make the galleries, drying occurs, leaving only the part exposed to the air, forming a shell, and inside there is no possibility of the juvenile stages of the flies breeding. It is therefore essential to know these beetles, and seek their protection as well as all the coprophagous fauna, since to solve the problems caused by flies it is necessary to implement integrated pest control (IPM), where these beetles play a fundamental role as biological controllers. To do this, it is necessary to learn to identify them and locate the places where they make their nests to avoid plowing the soil and the application of agrochemicals and thus be able to protect them.