Treecologic Inc.
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Friday Fact Corner: This little spined soldier bug (Podisus maculiventris) nymph isn’t reading the paper (probably) but it arrived in it to begin its IPM journey. IPM stands for “Integrated Pest Management” and is the practice of utilizing multiple skills, approaches, and disciplines to promote plant health. Releasing beneficial insects and organisms like this soldier bug are an increasingly large part of many IPM programs, especially in the urban environment. This is because beneficial organisms (often shortened to “bios” in industry) pose few or no health hazards to applicators and the general public, have few or no long-term environmental impacts, and do not require permits, licenses, or insurance to purchase and apply. Increasingly, native bios are becoming available for North American markets as identification and rearing practices are refined.nnNot every bio release is free from complications – the Asian or harlequin ladybird invasion is one such misstep. These beetles were released en masse in 1991 to combat soybean aphids devastating commercial crops in the United States. While the release program was an objective success, the beetles have become invasive, greatly expanding their range from their initial release sites and outcompeting native ladybirds. Worse still, they aren’t friendly – harlequin ladybirds tend to swarm structures in fall and bite if handled. Of course as bad as that is, it doesn’t come close to the poster child for bios gone wrong: the cane toad. These large terrestrial toads were brought to Australia from Central and South America to control pests in sugarcane, but they quickly developed a taste for the local wildlife and have been running riot ever since. Worse yet, the pest they were brought to control, the grey-backed cane beetle, isn’t even something they eat – the beetle lives at the top of the sugarcane plant, and the toad can’t climb!nnA successful bio release then needs to begin with groundwork – know your environment, and know your pests before you buy. Take aphids, for example: a small yard with a rosebush that gets infested by green peach aphids every spring, is a very different environment from a 500-acre orchard that has problems with woolly apple aphids. The general problem (aphids) is the same, but the scale of the locations, the host material size and density, and the organisms in question are all very different. In either case, releasing native ladybirds (2-spotted ladybird, since they are lab-reared and not wild-caught) will help. In the case of woolly apple aphids, because they also feed on roots, a treatment with predatory nematodes will hit their fossorial life stage. A hungry generalist predator like spined soldier bug, green or brown lacewing, or whirligig mite will round out the program – regular monitoring of pest and predator populations will let you know how well it’s working, and when to reapply bios. For the yard, a few ladybirds and hand-picking of swarm locations should keep everything looking great for spring!
