Natural predators controlling cyclamen mites in strawberry crops

Sometimes the best pest control is another animal. Instead of trying to poison a pest, let something that eats it keep the population down. That makes sense as a possibility. But sometimes matters: we haven't been given a rule that natural predators always outperform pesticides.

Now we get an example with two mites. Keep their jobs straight. Cyclamen mites are the pests damaging the strawberries. Typhlodromus mites are the predators eating those pests. Both are mites, so following the names matters more than simply remembering that mites are involved.

The timing helps explain how control works. Cyclamen mites arrive soon after planting, but they don't reach significantly damaging numbers until the plants' second year. The predators usually arrive during that second year and keep the pests below damaging levels. The goal is control, not necessarily eliminating every cyclamen mite.

I might wonder whether the predators could create some other problem. That's a reasonable question to keep open, but so far we're being told why this relationship helps. The next paragraph turns to what makes Typhlodromus effective.

First, the predators eat a lot, and their population can keep pace with the prey's. Both species reproduce through unfertilized eggs that develop into fertile females. In plain terms, reproduction doesn't require those eggs to be fertilized. The next figures help explain the population growth: cyclamen mites lay three eggs a day for four or five days, while Typhlodromus lay two or three a day for eight to ten days.

That is roughly 12–15 eggs compared with 16–30 over the stated reproductive periods. Don't mistake fewer eggs on a particular day for less reproductive capacity overall. Typhlodromus reproduce for longer. The point of these numbers is that the predators can keep up, rather than being overwhelmed by rapidly multiplying prey.

There is also a timing connection. Predator reproduction is in seasonal synchrony with prey growth: the predators reproduce when the prey population is growing. Reproducing rapidly wouldn't be as helpful if it happened at the wrong time of year.

What happens when the prey becomes scarce? In winter, the predators survive on honeydew produced by aphids and white flies. They aren't described as eating the aphids themselves. They reproduce only while feeding on cyclamen mites, so survival and reproduction are different here. They can remain alive through a period with little prey without continuing to reproduce on the substitute food.

The experiments now test whether those predators really matter. One group has both mites. The other is treated with parathion, which removes Typhlodromus but leaves cyclamen mites unaffected. That's crucial: the chemical kills the helpful predator, not the pest we're trying to control.

The result fits the prediction. With predators, pest numbers stay low. Without predators, the pests reach damaging levels. Applying a pesticide sounds like pest control, but this particular pesticide removes the thing doing the controlling.

The field results repeat the greenhouse pattern. When cyclamen numbers start rising in an untreated planting, the predators respond and reduce the outbreak. Cyclamen mites are about 25 times more abundant without predators. That comparison supports the importance of predation; it doesn't say untreated plants have no pests at all.

Our rough main-point prediction is that Typhlodromus illustrates how a predator can control a pest better than an ill-chosen pesticide. Keep the example connected to the opening idea. We spent most of our time on these mites, but their relationship shows how natural predation can keep agricultural pests in check. Neither the experiments nor the reproductive details are the whole point by themselves.