Helicoverpa outbreaks put pressure on GMO soybeans in Brazil

Several outbreaks of caterpillars from the genus, Helicoverpa, are attacking Intacta (Bayer) transgenic soybean crops in the Brazilian states of Mato Grosso do Sul, Mato Grosso and Maranhão.

The pressure caused by the caterpillars has attracted the attention of producers and researchers, since GMO technology should offer resistance to this pest, but the dry climate affecting the aforementioned areas has directly influenced the growing presence of caterpillars in the initial stage of the oleaginous plant.

Germison Tomquelski, researcher at Desafios Agro

Researcher Germison Tomquelski from the consultancy Desafios Agro said, ″The presence of the caterpillars is representative and is demanding insecticide applications at the start of the harvest.″

″We are facing a different scenario this year. There could be a trend towards the more intense occurrence of Helicoverpa in Intacta soybeans. It is a group of polyphagous pests, which multiply in the production system. It may be more challenging to deal with them going forward,″ he added.

According to Tomquelski, whether the main populations of the pest observed in MS and MT are Helicoverpa armigera, Helicoverpa zea or a hybrid is not known.

For Tomquelski, the application of insecticides, both biological or chemical, should preferably be done when the pests are in the initial stage of their development.

″In first and second instar caterpillars, bioinsecticides, such as baculoviruses, show a control efficacy of around 90%. For larger caterpillars, we recommend integrating chemical insecticides into management,″ he stressed.

Guilherme Ohl, researcher at Ceres Consultoria

Guilherme Ohl, researcher at Ceres Consultoria, said that it is ″essential for producers to anticipate the problem through monitoring, and have adequate tools at hand at the right time to take control.″

However, regarding the control of Helicoverpa, Ohl stressed that ″one technology must defend the other.″

″Baculoviruses are fundamental to integrated pest management (IPM), as well as chemicals, the 'traps.’ It is better to start a selected treatment, depending on the crop, when the monitoring points for average presence is one Helicoverpa per meter during the vegetative phase of the soybean, and 0.5 caterpillar of the genus, per meter, during the reproductive phase,″ he said.

However, according to Ohl, currently, ″the biggest fear″ of specialists is the fact that other species of caterpillars, in addition to Helicoverpa, ″are ‘escaping’ from the control of Intacta technologies.″

″Over the past two harvests, Helicoverpa zea escaped corn, went to cotton, and this year, we see the pressure occurring in soybeans. We also noticed an increase in the populations of the caterpillars, Spodoptera frugiperda, Heliothis virescens and Rachiplusia nu. They have potentially adopted to Bt soy technologies, which occupy 86% of the oleaginous plant planted in the country,″ he stressed.

Octavio Augusto Queiroz, agronomist and consultant at Evoterra Consultoria

Agronomist and consultant Octavio Augusto Queiroz from Evoterra Consultoria said the start of the soybean harvest was marked by outbreaks of Helicoverpa spp.

″We have been seeing an increase in caterpillar pressure for two years here. We believe that this comes from the correlation between the pests of second-season corn and soybeans. This scenario may get worse in the coming years,″ he added.

Marcelo Lima, technical manager of AgBiTech Brasil

Technical manager of AgBiTech Brasil, agronomist Marcelo Lima, explained that the Helicoverpa outbreaks at the beginning of the harvest, as well as the resilience of caterpillars against biotechnologies, caused concern, but the scenario is less serious compared to 2013 and 2014 when Helicoverpa armigera caused serious damage.

″Today, we have more effective management tools, from chemical and biological insecticides to attractants for moths,″ he added.

(Editing by Leonardo Gottems, reporter for AgroPages)