TAIPEI (Taiwan News) — Both lychee and longan fruit trees flower in April, which also corresponds with the spawning period for a major fruit tree pest, the lychee stink bug.

Changhua County took extra precautions this year, using drones to release parastitic wasps (Anastatus fulloi), which are a natural nemesis of lychee stink bugs, according to LTN. Boxes of these wasps were transported by drone to hard to reach areas to engage in natural biological control.

Changhua County’s Department of Agriculture said lychee trees are blooming well this year, even better than previous years. This is beneficial to local bees who are busy collecting honey and engaging in pollination at the same time.

For the sake of the bees, as well as their work in pollination, agricultural officials are encouraging farmers to stop using chemical agents during this important lychee flowering period, instead, making use of biological control methods like parasitic wasps.

Adult lychee stink bugs begin to appear in large numbers in May, and can damage fruit from July to August. During spawning, parasitic wasps prey on lychee stink bug eggs, with female wasps laying their eggs in the eggs of the lychee stink bugs.

This prevents lychee stink bugs from hatching, and it also helps give rise to more parasitic wasps, which emerge from lychee stink bug eggs 20 days later, further helping control the lychee stink bug population.

Farmers seek biological control methods for lychee stink bugs. (Changhua County Government photo)

The first wave of parasitic wasp release was completed on March 29, followed by a second and third release timed to take place at intervals of 10 to 14 days. A total of 1.44 million parasitic wasps will be released to protect local fruit trees.

Starting in May, drones will begin to spray eco-friendly pesticides such as saponins, which prevent lychee stink bugs from building nests. From past experience, this two-pronged strategy of parasitic wasps and natural pesticides has been quite effective.