In Somalia, an unprecedented effort to kill massive locust swarms with biocontrol

In recent months, the Horn of Africa has been invaded by desert locusts that have consumed food crops and pasture. For Kenya, it is the worst infestation in 70 years. One swarm there was estimated at 100 billion to 200 billion locusts, marauding through 2400 square kilometers. FAO warned again this week that the insects pose a severe humanitarian risk, as nearly 10 million people in the affected area already face food shortages because of recent floods and droughts. “We simply cannot afford another major shock,” Mark Lowcock, United Nations under-secretary-general for humanitarian affairs and emergency relief coordinator, said at the briefing. “Time is running out.”

Several factors caused the massive outbreak. In May 2018, a cyclone hit the desert “empty quarter” of Oman, Yemen, and Saudi Arabia. After the unusual rainfall, vegetation flourished, and the well-fed locusts increased their population 400-fold over 6 months. Normally, the populations would shrink when plants die after the desert dries out again, and timely control efforts can prevent populations from booming.

In this case, however, a second cyclone hit in October 2018 and the population continued to increase—an estimated 8000-fold by March 2019. The locusts headed to southern Iran, crossing territory that hadn’t seen the insects in 50 years, and moved east into India and Pakistan. Last summer, many flew south with prevailing winds into Yemen, where civil war prevented any spraying of pesticides. The swarms moved to Ethiopia and Somalia in October 2019.