How to breed phytophagous predators to control spider mites? - briefly
Establish a breeding program for predatory mites (e.g., Phytoseiulus persimilis) by supplying a continuous supply of spider‑mite eggs or factitious prey, maintaining temperature around 24‑28 °C, humidity near 70 %, and providing suitable oviposition substrates such as bean leaf discs. Release the mature predators onto infested crops at a density of 5‑10 individuals per square meter to suppress mite populations.
How to breed phytophagous predators to control spider mites? - in detail
Plant‑eating predatory mites are the most effective biological agents against spider mites. Successful mass production requires careful selection of species, optimization of environmental parameters, provision of suitable supplemental diets, and rigorous quality control.
Choose a species that matches the target pest and cropping system. Phytoseiulus persimilis excels on high densities of Tetranychus spp. in greenhouse tomatoes, while Neoseiulus californicus tolerates lower prey levels and broader temperature ranges, making it suitable for field crops. Amblyseius swirskii, a generalist, can suppress both spider mites and thrips on ornamental plants.
Maintain rearing chambers at temperatures between 22 °C and 28 °C, relative humidity of 70 %–80 %, and a photoperiod of 16 h light/8 h dark. These conditions promote rapid development and high fecundity. Use transparent acrylic containers with fine mesh ventilation to prevent escape and ensure adequate airflow. Provide a moist substrate, such as wheat bran soaked in water, to prevent desiccation.
Supply a factitious food source to sustain colonies when prey is scarce. Common options include:
- Typha pollen, applied as a thin layer on the substrate, supports oviposition and longevity.
- Ephestia‑kuehniella eggs, delivered in small droplets, provide high protein content.
- Artemia cysts, rehydrated in saline solution, serve as an alternative protein source.
Rotate supplemental foods weekly to avoid nutritional deficiencies. Introduce live spider mite eggs as the primary prey once colonies reach the adult stage; a ratio of 10–15 mite eggs per predator adult ensures adequate feeding without overloading the system.
Scale production by cascading cultures: start with a starter colony, transfer a defined number of adults to larger trays, and repeat until the desired population size is reached. Record the number of individuals transferred, temperature, humidity, and food type at each step to maintain consistency.
Implement quality checks before release. Verify species identity under a stereomicroscope, assess developmental time (average 2–3 days from egg to adult at 25 °C), and confirm predation capacity by counting spider mite eggs consumed in a 24‑hour assay (target >30 eggs per predator).
Release rates depend on crop stage and infestation level. For moderate spider mite populations, apply 10–15 predators per square meter, distributing them uniformly across the canopy. In severe outbreaks, increase to 30–40 predators per square meter and consider multiple releases at 3‑day intervals.
Monitor post‑release efficacy by sampling leaves every 2 days, counting spider mite eggs and adult numbers, and adjusting predator releases accordingly. Integrate with other IPM tactics, such as selective acaricides with low toxicity to predatory mites, to enhance overall control while preserving the biological agents.
By adhering to these protocols—species selection, controlled rearing environment, balanced diet, systematic scaling, and rigorous monitoring—commercial producers can generate robust populations of phytophagous predators capable of suppressing spider mite infestations across diverse cropping systems.