Phytophagous bugs become the worst pests of soybeans and corn in Brazil

Phytophagous stink bugs are currently the most important pests in the soy-corn production system, an article by Germison Tomquelski and Paulo Chagas, researchers from the consultancy Desafios Agro, has pointed out.

Left: Germison Tomquelski    Right: Paulo Chagas

″There are significant losses in soybean, corn, and cotton crops in Brazil due to pests. There are frequent challenges with new pests, from the lack of knowledge of biology, identification, problems of control alternatives, and even the wear and tear of some strategies,″ they said.

According to them, factors such as the presence of hosts throughout the year, plants remaining from previous harvests, called ‘tigueras’, combined with other factors such as favorable climatic conditions, high temperatures, and mild winters, are ideal for insects to multiply.

″Tropical agriculture is challenging, and the inappropriate use of some chemical insecticides and biotechnologies led nature to give us an answer,″ the researchers explained.

Pests previously treated as secondary began to cause significant damage to crops (‘pest shift’), in addition to those that already demonstrated high destructive potential, going through the resistance process, making it unfeasible and increasing, even more, the need for control.

The brown bug, Euschistus heros (Heteroptera: Pentatomidae), is widely distributed in crops in the Cerrado region.

However, other species of bugs are entering the agroecosystem, such as the green-bellied bug (Dichelops (Diceraeus) melacanthus and D.furcatus), occurring in certain areas that cause significant damage.

This species has a shorter cycle and greater reproduction capacity, in addition to remaining longer in the soil, attacking crops after emergence.

In general, the damage caused by stink bugs in soybeans occurs in the reproductive phase from the formation of the pods, also called the formation of the "penknife", leading to their fall and after the poor formation of the grains.

At this stage, bedbugs concentrate on these parts, both as nymphs and adults. In corn, the growth point of the plants is the target in the initial phase, with the stink bugs of the genus Diceraeus sp. which lead to the most extensive damage.

Its style manages to reach the meristem of the plants leading to their deformation, compromising the development and consequently the occurrence of ″dominated″ plants that do not produce ears.

″The bugs after the harvest can still stay in the area – straw and other hosts, or even go out to adjacent areas. This behavior has led to implementing management techniques for this pest until harvest, with population dynamics being increasingly important,″ they recommend.

″Faced with these challenging scenarios, only the rescue of Integrated Pest Management, with better knowledge of biology, sampling, and good control strategies, will lead the producer to win these battles, providing productivity and profitability,″ the specialists said in conclusion.

(Editing by Leonardo Gottems, reporter for AgroPages)