Nematode Assessment Calculator

Search efficiency is the fraction of the target predator:prey ratio's agents that can actually locate and attack a pest — no released organism finds every target in the field. Because the calculator divides the raw agents-needed figure by search efficiency, a less effective agent (say, a 30%-efficient generalist predator) requires proportionally more individuals released to achieve the same effective ratio as a highly efficient specialist parasitoid at 80%.

Inundative releases aim for fast knockdown of an existing infestation, so they use a high predator:prey ratio (roughly 0.2-0.5 in this calculator's terms) and typically a shorter program. Inoculative releases aim to establish a small, self-sustaining agent population that builds up over time, so they use a much lower ratio (around 0.02-0.1). Entering the wrong ratio for your goal either overspends on agents you didn't need or under-delivers the control you were counting on.

It comes from a simplified Nicholson-Bailey host-parasitoid model — fraction escaping predation approximated as e^(−a×P), where a is search efficiency and P is agent density per acre — which is a standard ecological approximation, not a guaranteed outcome. Actual suppression also depends on temperature, agent quality and health at release, and the pest's life stage, so treat the percentage as a planning estimate rather than a contractual result.

Agents per release is the raw count needed to hit your target ratio against the field's total estimated pest population in one release event. Agents per acre is that same release-event count divided evenly across the field area. Total agents for the season multiplies the per-release count by however many release events fit into your treatment window at the interval you specified, so it's the cumulative order quantity, not a per-visit number.