The Colorado potato beetle larva dangling from the beak of a tricky two-spotted stink bug becomes a nutritious autumn treat for this native predatory bug.
In keeping with our Halloween theme of visiting bugs in orange and black like harlequin bugs and Florida predatory stink bugs, this week we present a spooky story of a garden pest, Colorado potato beetle, and its predatory nemesis, the two-spotted stink bug. Anyone that has grown potatoes likely has encountered the Colorado potato beetle as larvae and adults as they shredded leaves and ravaged your plants. You may not have known that this traveler originated in Mexico where its aboriginal host was a member of the potato family called buffalo bur. When Spanish colonists arrived in Mexico with cattle, herds were driven from Mexico northward to markets in Texas. As cattle moved north, buffalo bur and the beetle moved with them. The weed and beetle continued to expand their range north and east during the 18th century. Potatoes were introduced from Europe to North America in the late 1700’s and by the 1800’s they too had expanded their range from New England westward. Sometime around 1860 the beetle acquired a taste for potato and made the jump from buffalo bur to its delectable new host. It has since spread to many places where potatoes grow, including the DMV.
After dining on eggs of Colorado potato beetle, this two-spotted stink bug moved along and rested near a pair of Colorado potato beetle larvae. While observing the larvae, it restlessly rubbed its antenna and forelegs together. Was it simply grooming behavior or was the predator contemplating its next meal? Nearby, a hapless Colorado potato beetle larva dangles from the beak of a two-spotted stink bug as it sucks liquified body tissues from its prey.
Orange and black Colorado potato beetle larvae play nasty tricks on leaves of potatoes.
A few years back while visiting a potato patch, I witnessed crowns of plants reduced to nubbins by Colorado potato beetles. Prowling around the vegetation were gorgeous nymphs and adults of the native two-spotted stink bug, Perillus bioculatus. Like their cousins, Florida predatory stink bugs and spined soldier bugs we met in previous episodes, predaceous stink bugs actively hunt and kill their prey. On a potato plant loaded with eggs of potato beetles, I watched a two-spotted stink bug with its beak inserted into an egg. Several beetle eggs had already been drained by the fierce predator. After taking its fill, the stink bug moved along and took a post near two potato beetle larvae munching potato leaves. As it watched the nearby larvae, it restlessly rubbed its antenna and forelegs together. Was this simply grooming behavior or was the predator contemplating its next meal? The actual attack of the two-spotted stink bug and other predatory stink bugs is much less of an energy-charged pounce and kill, but more of a seemingly gentle poke of the stink bug’s beak. Before the hapless victim escapes, the stink bug immobilizes its prey with toxic venom and then injects digestive enzymes into its victim. These enzymes help liquefy tissues in the body of the prey. A muscular pump in the head of the stink bug sucks nutrient-rich fluids from its prey.
As I wandered around the potato patch, I noticed that only a few plants had potato beetles with an attendant complement of stink bug assassins. Many healthy plants lacked beetles and stink bugs. How do stink bugs locate plants with potato beetles in a vast field of potatoes where many plants have no potential prey? Clever researchers discovered that as potato beetles eat potato plants, the leaves of plants release volatile compounds into the atmosphere. Hungry two-spotted stink bugs on the prowl for prey are able to detect the compounds from beetle-wounded plants and use them as an olfactory beacon to find beetle infested plants that house their dinner.
Although potato is common in their diet now, Colorado potato beetles first fed on other members of the potato family like buffalo bur. Males often guard their mates for long periods of time.
Sometime before the killing frost annihilates the remnants of your potato patch, pay one last visit to your plot and maybe spot predator and prey dressed in orange and black. Bug of the Week wishes you a spooky, happy, and safe Halloween.
Acknowledgements
The following fascinating studies were used to prepare this Bug of the Week, “Identification of Volatile Potato Sesquiterpenoids and Their Olfactory Detection by the Two-spotted Stinkbug Perillus bioculatus” by Bernhard Weissbecker, Joop J. A. Van Loon, Maarten A. Posthumus, Harro J. Bouwmeester and Marcel Dicke, and “Comparison of Perillus bioculatus and Podisus maculiventris (Hemiptera: Pentatomidae) as Potential Control Agents of the Colorado Potato Beetle (Coleoptera: Chrysomelidae)” by Judy Hough-Goldstein and D. McPherson. The great reference “Invasive Species” by Daniel Simberloff was also consulted for this episode.