Understanding Variable Rate Mating Disruption
A common pest management tactic in agriculture, mating disruption involves deploying synthetic pheromones to interfere with the mating process of certain troublesome insects.
In the early days, pheromones were only applied via passive release systems. These systems are heavily influenced by temperature and, as a side effect, their evening release rates can be unintentionally reduced even though target pests are at their most active.
Today, active release is the most popular choice as it enables consistent release rates when most impactful. However, given the inherent variability between seasons and pest flights, growers generally need to make concessions in terms of preference in covering the early or later part of a season. This is where variable rate mating disruption offers a distinct advantage.
What is Variable Rate Mating Disruption?
Variable Rate Mating Disruption allows Semios to release the pheromones in line with the pest's natural biology. Dispensing rates are increased during periods of high risk, and reduced during periods of low risk.
How Semios Variable Rate Mating Disruption Works
Leveraging in-field sensing technology, Semios can ensure higher mating disruption dispensing rates match peak pest activity by using:
- Automated camera traps that provide daily trap counts from within the orchard being treated. Entomologists then monitor traps and validate moth flight times on a nightly basis.
- Accurate degree days tracked by in-canopy weather stations, right down to the acre!
- Networked pheromone dispensers automatically adjust dispensing rates according to your orchard's pest activity.
Your pheromone dispensing rate increases with your orchard's target pest activity to better suppress the population. Because pheromone dispensing rates are increased and decreased in response to pest activity, you get extended coverage for late pest generations.
What Does The Research Say?
Emission Frequency vs. Dose
Recent Research – Burks and Thompson (2019)
Using programmable dispensers, a trend of decrease in male captures was observed with a decrease in time between aerosol emissions ranging between 30 minutes to 5 minutes. In an additional experiment, it was observed that greater trap suppression was achieved when the same amount of active ingredient per hour was delivered with 7 minutes between emissions versus 14 minutes between emissions.
Finally, 7 minute emission intervals were still observed to be superior compared to 14 minute intervals with double the dose of active ingredient per emission.
Daily Pheromone Release Window
In an additional trial within this study, it was observed that there was no significant difference in trap suppression between nightly dispensing windows of 4 or 6 hours compared to 12 hours which is the assumed commercial standard.
Additional trials were conducted and showed that implementing the understandings of emission frequencies and windows detailed above provided a significant reduction in damage to nonpareil almonds treated with mating disruption.
Semios’ Variable Rate Mating Disruption (VRMD) Implementation
- For years Semios has been using predicted and observed nightly pest biology to adjust the period in which specific doses of pheromone are applied nightly.
- For navel orangeworm (NOW), dose rate timings during hull split are impacted by a predictive model which outlines the effects of micro-climate on nightly pest activity windows.
- During hull split, rates on a nightly basis ranges up to 2X that of the assumed competitive standard rates.
- To achieve these 2X rates VRMD reaches the every 7 minute dispensing frequency outlined in Burks and Thompson (2019) that was shown to have a greater effect than frequencies of 14 minutes which is still shorter than the assumed commercial standard rates of approximately every 15 minutes.
- By increasing the frequency of emissions up to 2X the commercial standard rate, there is also a 2X increase in dose of active ingredient.
Semios places importance on application rates during specific periods of time during the evening.
Based on the work by Burks and Thompson (2019), it was shown that there was no statistical difference between dispensing during a 4, 6, or 12 hour window ending at sunrise. Although 12 hours is the understood commercial standard, Semios has implemented windows ranging from 12 to 6 hours depending on the time of year, and the associated variability in timing of pest activity.