Agricultural aviation and pollinator protection

Agricultural crops may depend on, benefit from or not depend on the pollination service performed by bees. We can cite perennial plants as an example of those dependent on pollination, as without bees there would be no production. The benefited crops are those that have an increase in production when pollinated. Therefore, harmony between agriculture and beekeeping is essential. And when talking about integration between these activities, the main and most sensitive issue involving the protection of pollinators is the use of agricultural pesticides in the vicinity of places where bees are present. But what few know is that managing plants with pesticides and keeping bees in these areas is perfectly possible.

Most of the products are applied to the plant using the spraying technique, which consists of the formation of a spray mixture, made up of a mixture of active ingredients (insecticides, fungicides, herbicides and foliar fertilizers) with the carrier (water and adjuvants). Most agricultural pesticides are applied in the form of liquids and reach the plants through the aerial part (leaves and stems). There are few products applied in solid format or on the root system.  

In the case of aerial application of pesticides, the syrup leaves the “hopper” (tank in which the spray solution is located) of the plane through the pressure created by the hydraulic or wind pump and travels through the system piping reaching the booms. There, the liquid will encounter a physical barrier, that is, a funnel in the place where it will pass, which are the spray tips. The liquid will be pushed under strong pressure into the small holes inside the tips and this will divide the syrup into small, thousands of particles, creating drops: this is how the spraying process takes place.

Once created, the drops will be released into the environment and the objective is for as many of these particles as possible to reach the desired target, which, as previously mentioned, are the leaves (adaxial or abaxial part), stems and even the soil.

Every drop that does not reach the desired target is considered drift, and to prevent this from occurring, it is important to know the techniques that offer greater efficiency so that the syrup fractionated into particles reaches the target and the set of these techniques is called application technology.

Some factors are limiting for safe operation, such as, for example, wind speed and direction, relative humidity and ambient temperature. Combining these factors with application technology can achieve the best result in bee safety.

To make it easier to understand the integration between limiting factors and application technology to promote safe spraying, we can divide the process into three stages: before starting the aerial spraying operation; during spraying; after spraying.

Before starting the aerial spraying operation

It is essential to know the area where the application will be made. To do this, critical points must be monitored, such as river sources, water sources, environmental preservation areas, residences, animal husbandry and apiaries. To carry out this survey, there are a variety of tools available, such as satellite or drone images and georeferencing systems. Along with the survey, it is important to specifically map the apiaries close to the application areas. In this way, the pilot and the agronomist responsible for the operation will be able, together, to outline flight strategies and techniques for creating and applying the drops in order to prevent them from drifting and arriving close to the apiaries.

With agriculture increasingly modern, we have improved our ability to monitor pests, diseases and weeds, making us more efficient in controlling these problems. By carrying out the operation at the right time and using the recommended dose and product, it is possible to considerably reduce the number of sprays during the harvest, providing greater harmony and safety for bees in agriculture.

It is important to highlight that, for each product applied, there is a dose recommended by the manufacturer, which needs to be followed when preparing the syrup, reducing the risk of applying a dose greater than necessary of the active ingredient and consequently generating waste and the product being more harmful to bees.

During spraying

After identifying the type of pest, control planning is carried out and depending on the problem identified, it is possible to use selective insecticides, which consists of a mechanism to control the pest without negatively altering the activity of non-target organisms existing in the area, such as natural enemies. and pollinators.

We can also highlight that advances in technology in the production of agricultural pesticides have increased the range of molecule options, such as biological products, with emphasis on insecticides. These products are based on bacterial, fungal microorganisms or plant extracts. These molecules may be little harmful to bees when compared to non-biological insecticides.

Another efficient tool in pest management in agriculture is biological control. The basic premise is to control pests and disease-transmitting insects through the use of their natural enemies, which can be other beneficial insects, predators, parasitoids and microorganisms, such as fungi, viruses and bacteria. These products can be applied through aerial spraying, as an example we can mention the use of Metarhizium, a genus of fungus, in pasture areas and in sugar cane cultivation.

Regardless of the product to be used, before starting the aerial application, the pilot – together with the field team – needs to check the variables that limit the safety and efficiency of the droplet's arrival at the target, and, in this way, reduce the drift risks, which are, as previously mentioned: temperature, relative air humidity and wind speed.

For these variables, there are minimum and maximum values ​​that need to be respected. If any of the factors mentioned are outside the recommended limits, the operation must be suspended immediately.

After spraying

Once the aerial application is complete, a map is generated with all operations carried out through the aircraft's DGPS system. In it, it is possible to check the paths and opening and closing points of the spray solution passage through the spray bars and the points at which the aircraft maneuvers were carried out, this way it is possible to monitor the entire operation.

Along with the map, it is mandatory to deliver a field report describing the operations carried out by the aircraft in the work area, with data on wind speed, temperature and relative humidity at the time of application and the products with their respective doses used. This material is prepared and signed by the qualified professional who must be technically responsible for the aerial application.

We can conclude that it is possible for pollinators to coexist well with management techniques that protect the productive potential of crops in agriculture. It is worth noting that in the operation involving aerial application, we emphasize the existence of legislation, supervision, trained professionals and protocols to be followed. These factors, combined with techniques that guarantee the efficiency of the operation, are fundamental for environmental and food safety in the use of agricultural pesticides.

By João Miguel F. Ruas, master in agronomy from the State University of Londrina (UEL)