Moisturized sheltered sachets are potentially useful for the efficient release of selected predators in a wide range of humidity environments

Slow-release sachets of predatory mites are commercially available for controlling small pest arthropods in many crops. We recently developed plant-attached shelters containing sachets and felt patches, called “sheltered sachets”, to protect predators against pesticides and wet conditions, and enhance their release to crops. However, this release system appeared to be vulnerable to dry ambient environments. To address this problem, we developed “moisturized sheltered sachets”, containing water-absorbed polymers as a humidifier, and investigated the numbers of Neoseiulus californicus and Amblyseius swirskii released from three different release systems, at low, moderate, and high RH. Irrespective of predator species and RH (excepting A. swirskii at high RH), more predators were released from the moisturized sheltered sachets than from the sheltered sachets and/or normal sachets. Thus, moisturized sheltered sachets appear to be potentially useful for the efficient predator release in a wide range of humidity environments.