Larger caterpillar populations worry producers

The presence of pests such as spodoptera spp. And helicoverpa spp. has been increasing in Brazilian crops. According to Germison Tomquelski, from Desafios Agro, climatic factors, such as the prolonged drought in the Cerrado, combined with the evolution of agricultural practices and the increase in the cultivation of transgenic plants, are contributing to the proliferation of these pests in several crops: soybeans, corn, cotton and pastures.

The lack of rain and natural enemies, combined with a management strategy that does not break the cycle of these pests, favors the population growth of caterpillars in several agricultural regions of Brazil.

Climatic factors

Recent years have been marked by adverse weather conditions in the Cerrado, with prolonged droughts of up to 180 days without rainfall. This scenario has impacted the presence of natural enemies, allowing pests such as spodoptera spp., a caterpillar that is difficult to control, to proliferate a lot.

Tomquelski points out that this imbalance between pests and natural enemies increases the risk of infestations, since the caterpillars find few barriers to reproducing and spreading.

With the return of rains in some regions only in mid-October, there has been an increase in the presence of caterpillars on plantations, especially in the initial planting phase, which makes crops more vulnerable. This scenario represents a warning for a possible year of high pest pressure, requiring extra attention from producers.

Management and control

The main recommendation for producers is to eliminate pest hosts through practices such as controlling weeds that serve as a bridge for the survival and reproduction of caterpillars.

However, the effectiveness of control depends on a well-structured strategy that assertively combines biological and chemical methods.

Biological control is recommended for early-stage caterpillars, but success depends on timely application. Biological products may have reduced performance on large caterpillars. And their effectiveness depends on a well-planned strategy.

In turn, the use of chemical products may be necessary, especially in cases of resistance. However, indiscriminately increasing the dosage is not recommended and should be carefully evaluated with the guidance of experts and companies supplying insecticides.

For an effective approach, Tomquelski suggests detailed knowledge of the pest life cycle, especially spodoptera spp., which has shown resistance to transgenic crops with Bt (Bacillus thuringiensis). This resistance is particularly evident in Bt soybean, corn and cotton crops, which, despite being designed to control pests, have not been fully effective against some species of caterpillars.

The role of weeds

Another crucial point raised by experts is the management of weeds that serve as hosts for pests. Plants such as trapoeraba (Commelineae spp.) and goosefoot grass (Eleusine indica), spread throughout Brazil, provide shelter for caterpillars and other harmful insects, such as the green-bellied stink bug (Dichelops spp.).

With the elimination of these weeds with herbicides, the caterpillars end up migrating to the crops of interest, increasing losses for producers.

Furthermore, regular sampling is essential to detect and control infestations efficiently. In an adverse year, constant presence in the field, combined with sampling, allows early identification of caterpillar outbreaks, enabling precise interventions and reducing losses.

Transgenics and climate perspectives

Since the introduction of Bt transgenic crops, the Brazilian agricultural scenario has changed significantly. spodoptera spp., previously more restricted to corn, has expanded its presence to other Bt crops, highlighting the need for new control strategies, says Tomquelski.

In a system with little cycle break, as is the case with Bt production, pests find food all year round, creating a "green bridge" that favors their continued survival and reproduction.

Climate forecasts for the coming months also indicate possible dry periods in December and January, which could further exacerbate the challenge of pest control, requiring producers to be prepared with efficient monitoring and management strategies.