The wasps are only 1 or 2 millimetres long fully-grown but they have an ability to paralyse and destroy other insects, including many of the most destructive crop pests, by delivering a zombie-inducing venom in their sting.
I love stories like these. Two years ago I remember standing over a patch of carrots I let go to flower and counting twelve species of wasps. Carrots and their relatives, such as parsnips, cilantro, lovage and fennel, produce small flowers that tiny insects such as these wasps can get. You can think of the nectar as the wasp version of an “energy drink” and the other insects they prey upon as a “protein shake.” Organic farmers use these feeding relationships to keep pests at bay. Having some wild spaces among the farm landscape where favored flowers can bloom helps grow food.
Image caption: A predatory wasp sips nectar from a plant in the carrot family.
Plant diversity in the farmscape is also critical for pollinating crops. Some intriguing research has just been released.
The decline of honeybees seen in many countries may be caused by reduced plant diversity, research suggests.
Bees fed pollen from a range of plants showed signs of having a healthier immune system than those eating pollen from a single type, scientists found.
This specific line of study is fairly new, but the general principle is well established. Dietary diversity for many animals gives them a range of metabolically important chemicals. If you feed animals on a narrow diet, they typically get diseased. We know this about pets and livestock, and now we are discovering its importance for honey bees.
I recently spoke to a graduate student studying bumble bees in the Willamette Valley of Oregon and was glad to hear that both native and honey bee populations are thriving. She said that her professors suspected, and were analyzing some data to confirm, that high crop and landscape diversity in the area meant that bees were well fed throughout the summer.
The organic system plan required by the National Organic Standards includes a description of how the farm will protect and enhance biodiversity. By growing many kinds of crops, restoring native habitats, and even creating artificial structures like hedgerows, a positive pay back accrues when it comes to lowering pest pressures and increasing pollination rates.