Assessing the influence of biotic and abiotic factors on the efficacy of spring flooding as a means of controlling the blackheaded fireworm

Description

Most cranberry growers currently use chemical pest control methods, e.g., synthetic insecticides and bio-insecticides, to control the blackheaded fireworm (Rhopobota naevana).

This insect is a major cranberry pest that can cause crop losses of up to 95%. The insecticides currently authorized for use in organic farming provide inconsistent and limited effectiveness. Each year, the blackheaded fireworm is present in significant numbers, and repeated insecticide treatments are required to reduce their populations below the economic threshold for damage.

The fact that there is only one bio-insecticide (Entrust, Spinosad) registered for use by organic cranberry growers makes this crop especially vulnerable. Cranberry bog flooding is a method that was commonly employed to control cranberry pests prior to the development of synthetic insecticides. A 48-hour flooding at the end of May is still used to control the cranberry weevil.

In recent years, significant declines in blackheaded fireworm populations have been achieved with this practice. However, the reasons behind the success of spring flooding in controlling the blackheaded fireworm are poorly understood, with the result that the applications vary in efficacy.

Objective(s)

• Assess the impact of biotic and abiotic factors on the effectiveness of spring flooding in order to develop a non-chemical method for controlling the blackheaded fireworm in organic farming.
• Identify the larval stages most vulnerable to flooding.
• Determine the optimal flood times.
• Assess the influence of temperature and the levels of dissolved oxygen in water on mortality rates.
• Assess efficacy rates in the field.