Features Production Research
Viral insecticide registered for codling moth control in Canada

Apple production has
traditionally occupied an important place in the agricultural economics
of Eastern Canada. In recent years, consumers have become increasingly
concerned about human health and environmental stewardship but still
want to be able to purchase fruit with cosmetic appeal at low and
stable prices.

An example of codling moth damage in apple. Contributed photo

Apple production has traditionally occupied an important place in the agricultural economics of Eastern Canada. In recent years, consumers have become increasingly concerned about human health and environmental stewardship but still want to be able to purchase fruit with cosmetic appeal at low and stable prices.

In light of this, fruit growers have exerted considerable effort over the years toward addressing consumer expectations, even though the range of alternative methods for legally maintaining fruit quality is rather restricted. Enter VirosoftCP4, the first viral insecticide registered in Canada for agricultural use.

The target insect and its market
In apple orchards, numerous insect pests can exert constant negative pressure on the fruit and the tree. Among them, the codling moth, Cydia pomonella, is a major pest of several orchard crops (e.g., apple, pear, plum and nut) throughout major apple-producing areas of the world. In relatively dry zones (e.g., the Northwest of North America, Italy, Argentina, and Australia), the management of this pest requires several insecticidal treatments per year. In relatively wet zones (e.g., the Northeast of North America), this insect was controlled until recently by insecticidal treatments targeted against other insects, notably the plum curculio. However, several populations of codling moth have recently developed resistance to insecticides all over the world, resulting in less effective treatments. Moreover, the legal context framing the use of pesticides has been tightened in several countries, including Canada, where azinphosmethyl has been excluded from the list of registered pesticides by the Pest Management Regulatory Agency (PMRA) effective December 2007. Some alternative methods are available to control this insect, including mating disruption with pheromones. However, this method incurs important costs and requires complementary tools that have very different modes of
actions in case of failure.

Codling moth granulovirus
The codling moth granulovirus (CpGV) is specific to this insect and innocuous to non-target organisms, including other insects present in orchard, birds and mammals. This granulovirus is very effective and ingestion of one to two granules by a young codling moth larva causes the death of the insect. This virus must absolutely be ingested by a larva to have an insecticidal effect. Once ingested, the encapsulated virions are released, penetrate in the insect by the cells of the stomach and, upon multiplication, cause the death of the insect in a few days. Dead larvae may be infection sites for the other larvae of codling moths.

Virosoft
In the world, few companies produce insecticidal formulations of codling moth granulovirus. In 1997, the company BioTEPP Inc. of Mont St-Hilaire, Que., undertook a research program in partnership with the Horticultural Research and Development Centre of Agriculture and Agri-Food Canada at Saint-Jean-sur-Richelieu, Que. This work resulted in the isolation and commercial production of a codling moth granulovirus. This virus, available under the trade name Virosoft, is registered in Canada and the U.S. Produced in Cap Chat in the Gaspé Peninsula, it is obtained by infection of live larvae and requires mass rearing of the codling moth.

For four years, various experiments were carried out in an organic orchard near Mont St-Hilaire, Que. The results showed that the product is a reliable tool to manage codling moth in this type of production. Several field studies were also conducted to evaluate the product’s virulence against codling moth, its persistence in orchard, its compatibility with various additives and its effectiveness. These studies, conducted in Quebec, Ontario, British Columbia and in the states of Washington, Michigan and New York, have shown the effectiveness of Virosoft in various agronomic conditions. They are also important so that the fruit growers can familiarize themselves with this new technology. As the virus persists only a few days once sprayed on the apple tree, the treatments must be made in an optimal way to impact the young larvae before they penetrate the fruit.

The application of Virosoft requires particular attention. As young codling moth larvae feed during a short period of time before entering apples, it is necessary to synchronize the moment of application with larval emergence, so that they ingest Virosoft before penetrating the apple. The quantity of virus ingested depends on the concentration and the exposition time of the larva to the product. Regular orchard monitoring for codling moth and the appropriate timing of the application – using a biofix – are two essential conditions for the use of Virosoft.

The future
Fruit growers are eager to adopt new methods to manage their orchards in an effective and responsible way. As Virosoft has been tested in several localities of North America, several producers know the existence and the value of this insecticide specific to codling moth. Like conventional insecticides, it requires dedication and it is compatible with other control methods, such as mating disruption. In this context, BioTEPP invests continuously to optimize the production of VirosoftCP4. It also conducts new projects to develop other viral insecticides and environmentally friendly products. Oligosol Inc, who collaborated with Biotepp, is proud to have make history in Canada with this product and looks forward to develop other innovative pest management solutions.
   
Caroline Provost, José Valéro and Dr. Harnaivo Rasamimanana are with BioTEPP Inc, based in Mont St-Hilaire, Que. Dr. Charles Vincent is an agronomist with Agriculture and Agri-Food Canada, based at the Horticulture Research and Development Centre in Saint-Jean-sur-Richelieu, Que.