As giant swarms of locusts spread across East Africa, the Arabian Peninsula and the Middle East, devouring crops that feed millions of people, some scientists say global warming is contributing to proliferation of the destructive insects. The largest locust swarms in more than 50 years have left subsistence farmers helpless to protect their fields and will spread misery throughout the region, said Robert Cheke, a biologist with the University of Greenwich Natural Resources Institute, who has helped lead international efforts to control insect pests in Africa. “I’m concerned about the scale of devastation and the effect on human livelihoods,” Cheke said, adding that he also worried about “the impending famines.”e change