Science for Brazil (Reino Unido)

Biocontrols against African Invader

Publicado em 04 dezembro 2014

An insect pest named the cotton bollworm that originated in Africa, is causing havoc with crops in Brazil, prompting a nation that’s already a significant user of pesticides, to find novel means of eradicating the alien intruder.

The cotton bollworm, Helicoverpa armigera, is known in Asia, Europe and the Pacific. Globally it does around US$5 billion worth of damage annually, and a significant portion of pesticide use in China and India is dedicated to eradicating it.

Now it’s Brazil’s turn, with infestation reports from farms in the states of Matto Grosso, Bahia, Tocantins and Goias. Experts fear the worm could do more damage to the country’s cotton crops than the traditional boll-weevil. You can read more about it here.

It was first identified in Brazil in February 2013. It has attacked soy, cotton, maize, common beans, chick peas, flax, sunflower, winter grains, citrus, wheat, barley, oats and sorghum. In consequence, the Brazilian Agriculture and Livestock Research Company (Embrapa) declared an A1 emergency quarantine, which consists on declaring this pest a high risk plague due to the economic damages it can generate. In early 2014, Embrapa even had its own travelling roadshow crisscrossing the country to educate farmers.

However, yet more pesticide use may not be the answer, according to José Roberto Postali Parra, Professor of entomology at the Luiz de Queiroz Advanced Agricultural College faculty of the University of São Paulo (Esalq-USP). He believes biology, not chemistry, is the science that will deliver the solution for Helicoverpa armigera.

In part due to its embrace of genetically-modified seed varieties such as Roundup-ready soybeans and maize, Brazil is already a major user of agricultural chemicals, with a market of around US$10.5 billion. Nevertheless, applications per hectare trail far behind South America’s leader, Costa Rica. In 2012, Brazilian farmers purchased over 620,000 tonnes of agricultural chemicals, according to the environment agency IBAMA.

Industry reports suggest pesticide use has risen 58% percent between 2010 and 2013 due to the advent of new pests including Helicoverpa armigera. According to an industry body, Sindiveg, growth has been led by insecticides and herbicides. Insecticides jumped by 40% to become the largest segment in the chemicals market during the first seven months of 2013 at US$1.36 million.

As a major commodity player and the world’s largest producer of soybeans, agricultural productivity is an issue of national significance to policymakers. So far, they have embraced all the apparatus of high-technology, big-ticket agriculture, with mechanisation, GMOs, and large-scale usage of herbicides and pesticides.

However, researchers including Prof. Parra believe the moment is ripe for Brazil to take a new approach by embracing biological controls of Helicoverpa armigera and other pests.

Much work has been done on the pheromones, hormones and attractor chemicals secreted by insects as part of their mating process. Volatile plant attractor chemicals known as Kairomones are also used to “divert” insects in pursuit of nectar-bearing flowers. Once synthesized, such chemicals can be deployed in fields to attract and then destroy millions of insects and so prevent them from reproducing further. Biocontrols also use predator insects to destroy targets. This is the way to catch the dull-looking brown moth that is the flying adult bollworm.

Study of biocontrol mechanisms has an established literature and the practice has been in development for more than 20 years. But in Brazil it is relatively new.

The work is being carried out by the National Institute for Semiochemicals in Agricultural Science and Technology. Prof. Parra leads a group of five principal investigators. You can visit their website here.

INCT is financed by the São Paulo Research Foundation (FAPESP), which supports biodiversity-based research at leading universities in Brazil’s leading state for production of biofuels, coffee and other agricultural commodities. INCT also receives support from federal government agency (CNPq) and from the Ministry of Science, Technology and Innovation (MCTI).

Embrapa takes a very traditional approach to pest management, and the agricultural chemicals lobby is well-entrenched in Brazil. Nevertheless, Parra told a recent agricultural science seminar in São Carlos that the moment was ripe for embracing new strategies.

The Bollworm, he said, was “a very difficult pest to deal with. The indiscriminate use of pesticides in Brazil has created a series of imbalances, which make the use of biological controls essential for dealing with this pest.”

One potential control agent identified by Parra is the carnivorous wasp Trichogramma, already used against agricultural pests, and which is known to attack Helicoverpa armigera. You can watch a video about using Trichgramma by clicking here. The sheer scale and range of Brazil’s agriculture, and the limited nature of its rural extension services, mean that new techniques will have to be developed for detecting pests and spreading their biological control agents. One possibility is the use of drones, he said.

Parra told the conference that the moment was ripe for the development of biocontrols in Brazilian agriculture. “If we continue using insecticides in an uncontrolled manner, these pests will simply increase. We need to create favourable conditions for biocontrols by encouraging biodiversity, by developing a critical mass of specialists in the field, and through the further development of agribusiness.”

You can read a full article (in Portuguese) by Brazilian journalist Fabio Reynol by clicking here.