Vulnerable Squash Bugs Have a Bizarre Way of Growing Healthy Bacteria in their Gut to Stay Alive
Squash bugs, an agricultural pest that is both common and challenging to manage, rely on healthy bacteria in their gut for growth and survival. However, when they are born, they do not inherit any bacteria from their parents, leaving them susceptible until they acquire a microbiome.
A recent study published in the journal Current Biology reveals that young squash bugs instinctively seek out and consume the feces of older squash bugs to obtain these beneficial bacteria.
“This is a directed behavior,” comments co-author Jason Chen.
“They’re not just feeding on something that has feces on it because they live in a gross environment. They’re deliberately seeking out the feces and slurping it up.”
The study shows “that the squash bug nymphs only feed on feces from adults of their own species.”
To test this behavior, the researchers created “arenas” to observe the preferences of squash bug nymphs. When given the choice between feces and a saline solution, the nymphs consistently gravitated towards the feces of adult squash bugs of their own species, even in darkness or from a considerable distance. Further investigation revealed that the bugs might be attracted to the odor of the feces.
“It’s just as simple a test as you could possibly design, and what made it so great was how clear and shocking the results were,” remarks co-author Scott Villa“They just immediately went to the side where there was fecal matter available.”
The researchers documented this feeding behavior and observed that when the bugs reached the feces, they used their mouthparts to penetrate the mass and liquefy it with their saliva. They then consumed the feces by slurping it up with their tongues. This particular feeding behavior had not been previously described in squash bugs.
While other insects acquire their microbiome from feces in their environment, this usually happens when the mother deposits her feces on top of the eggs, allowing the hatchlings to consume the beneficial bacteria immediately after birth. In contrast, squash bugs must actively search for feces in the environment to survive.
“A lot of the other species don’t need this attraction behavior because it’s on a platter for them as soon as they hatch. Our guys have to work for it,” points out Villa. “For something this important, you should automatically pass it on to your kids, but they don’t for some reason. That’s the intriguing part.”
The team’s future research will focus on why squash bugs invest additional energy into obtaining healthy bacteria in this manner. Meanwhile, the discovery of the species-specific fecal preference of squash bugs could aid in the development of pest control strategies. Squash bugs feed on the fluids within leaves instead of chewing them, rendering many conventional pesticides ineffective. However, their vulnerability without a microbiome and their preference for feces from their own species could be a potential weakness to exploit.
“These pests are very difficult to control, because they’re not exposed to conventional insecticides,” adds Chen. “But if you can target them at this vulnerable stage in the life cycle, that’s a really nice way to target a specific agricultural pest and nothing else in the ecosystem.”
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