Development of a forecasting method of spring populations of Colorado potato beetles for use in reduced input potato production decision making systems

Project code: PRR03-060

Project Lead

Gilles Boiteau - Agriculture and Agri-Food Canada

Objective

To develop a user-friendly computer program for prediction of Colorado Potato Beetle infestation in potato field

Summary of Results

A Colorado Potato Beetle (CPB) forecasting model for use in commercial potato insect Integrated Pest Management (IPM) programs was developed based on data collected from 10 and 12 commercial potato fields in 2004 and 2005, respectively. This spring colonization data established that current year potato fields nearest previous year potato fields are colonized by significantly more beetles than more distant fields. The emergence pattern of CPB from overwintering sites was estimated using a logistic degree-day model and compared to the corresponding pattern of field colonization. This comparison revealed the presence of a reservoir of colonizers estimated at 35% of the season long colonizing population. This reservoir of colonizers emerges before potato plants break the ground, and probably explains the rapid and abundant colonization of fields closest to previous year's fields.

Results confirmed for Canada the season long dispersal range of 1.5 kilometres (km) for adult CPB but showed a steep decrease of beetle abundance as a function of rotation distance, with a levelling between 200 and 700 metres (m) in contrast to the almost linear decrease reported elsewhere. Also, there was no evidence that rotation distances of less than 1.5 km (the season long dispersal range of the beetle) delayed colonization.

In terms of pest management, the findings of this study confirm that only long (at least 1.5 km) rotations can prevent CPB colonization. However, the data also reveal that relatively short rotations of 200 m can be as effective as longer rotations of 700 m or more, at least at low beetle density.

The output of the model developed from this information is a probability distribution for the location and state of a beetle at time, t, after its emergence. The output can be used to compute the expected number of beetles at any location given a specified pattern of emergence. Model simulations can easily be run for the different combinations of previous year and new field locations planned by growers to help them select crop rotation locations that will minimize the risk of CPB population build-up and thereby reduce dependence on insecticide control.

A manuscript detailing the results of the project is in preparation for publication, and information for growers in the use of this model is under development. For more information, please contact Dr. Gilles Boiteau, the Potato Research Centre, Agriculture and Agri-Food Canada Fredericton, New Brunswick.

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