Colorado potato beetles can decimate spud crops by devouring the plants’ foliage. There’s more unsettling news: Each female Colorado potato beetle can lay about 600 eggs in a growing season. And the species—Leptinotarsa decemlineata—easily develops resistance to pesticides.
What might slow their devastation of potato crops? Perhaps cannibalism, say researchers at the University of Maine.
UM scientists Everett Booth, Andrei Alyokhin and Sarah Pinatti observed that in a laboratory, Colorado potato beetles faced with starvation, crowding and no opportunity to disperse ate beetle eggs, young beetles, injured beetles and other adults, particularly those who had just molted and were soft.
Alyokhin, an entomologist and director of the UM School of Biology and Ecology, says even when Colorado potato beetles were given a choice between other adult beetles and mealworms, they ate their own species. The cannibalistic behavior might decrease in fields, though, as beetles facing difficult circumstances could disperse, he says.
During periods of limited food availability, Alyokhin says engaging in cannibalism is a “lifeboat strategy”—it prolongs survival and prevents population extinctions.
The researchers say Colorado potato beetle cannibals get an immediate benefit—a meal—without investing a lot of search time. The cannibals also ingest beneficial nutrients that their regular diet doesn’t provide. And survivors increase the relative amount of available resources by eliminating same-species competitors.
The researchers say growers could try to protect their potato crops by utilizing agricultural practices—including crop rotations and push-pull strategies—to create field conditions that favor Colorado potato beetle cannibalism.
Sequential crop rotation can interrupt the life cycles and habitat of the potato beetles. Push-pull strategies introduce stimuli to make potato plants unattractive and simultaneously lure the beetles toward an attractive source, where they concentrate and can more easily be destroyed.
The team’s findings are in the article “Adult cannibalism in an oligophagous herbivore, the Colorado potato beetle” published in April 2017 in the jouirnal Insect Science.
Source: Potato Pro