Nature's silent language: Decoding the way insects use chemical signals to communicate

In the insect world, an elaborate language of chemical signals is used for daily survival and interactions. Insects use chemical signals to find mates, hunt for food, and avoid becoming prey themselves.

While humans occasionally witness insect signals, such as the glow of fireflies, most of this communication remains shrouded in mystery.

Researchers from SRI International, in partnership with experts at Virginia Tech and Rutgers University, are exploring the enigmatic world of insect communication. They aim to unravel these chemical conversations in the hope of developing more sophisticated pest control methods, safeguarding crops, and mitigating the spread of diseases transmitted by biting insects.

The researchers recently made a significant stride in this direction, with their findings published in the journal Protein Science. According to study co-author Paul O’Maille, the team has developed a unique method to identify specific sections of genetic code that generate the chemicals which insects utilize for communication. 

“Pest control is a longer-term goal here, particularly in agriculture. We need to decode this language, be able to intercept it, and maybe redirect it in intelligent ways,” said O’Maille.

Genes give insects their chemical signals and a unique “voice”

The primary chemical signals used by insects for communication are terpenes. They are a class of chemicals that easily vaporize and disperse over a broad area. This makes them an efficient means for insects to transmit their messages.

Until recently, scientists believed that insects could not produce terpenes independently, but obtained them either from their diet or through symbiotic relationships with microbes. However, a recent revelation turned this assumption on its head. 

“Just in the last handful of years, my collaborators and others discovered that insects actually have genes to encode for enzymes called terpene synthases, and that is the mouthpiece of this communication form,” said O’Maille.

These enzymes enable insects to produce their unique terpenes. They effectively give them a voice in the chemical cacophony that orchestrates their daily interactions.

Recognizing this potential, the researchers embarked on a quest to discover similar genes across different insect species.

Applying his extensive knowledge from studying plant terpenes over the past decades, O’Maille broke down the chemistry of terpene synthesis. By doing this, she was able to identify the genetic patterns associated with the terpene synthases.

“We’ve basically put together a ruleset for understanding the natural history of how these terpene synthases came to be, and that leads to a heuristic, or a method, to predict whether a gene is a terpene synthase or not,” explained O’Maille. “Using that heuristic, we see that there are loads of these terpene synthase genes across different insects – they’re quite prevalent.”

Decoding insects’ chemical signals to help control behavior 

The team was able to identify hundreds of potential terpene synthase genes within the genetic sequences of various insects. Though their work has covered only eight of the twenty-nine recognized insect orders so far, the data suggest that terpene-based communication evolved independently across multiple lineages.

The new blueprint for identifying terpene synthases could potentially empower scientists to understand more about how terpenes are employed in insect communication. This knowledge could be harnessed to manipulate the insects’ actions. 

For instance, if the terpenes attractive to crop-destroying insects could be identified, decoy plants could be engineered to emit these chemicals and divert the insects away from valuable crops. “Our ability to decode that conversation gives us more options,” said O’Maille.

Implications of the study and knowledge gained from terpenes

The experts highlight the potential applications of their methodology beyond the insect world. The novel method they developed to predict terpene synthase coding regions in the genome could very well serve as a versatile tool that can be extended to various classes of enzymes in a diverse array of species.

“Right now, we can sequence genomes at-will, but we can’t interpret the genome very well,” said O’Maille. “Our work provides a roadmap for developing heuristics for other classes of enzymes to have more accurate predictions of the functions of genes.” 

In their quest to decipher the language of insects, the researchers have not only provided vital tools for pest control and crop protection, but have also unlocked a potential method to interpret the intricate language of genomes.

More about insect communication 

Insect communication is a complex and fascinating subject. Insects have evolved a variety of methods to convey information and to interact with each other. Here are some main types of insect communication:

Chemical communication (pheromones)

Many insects, like ants, bees, and moths, use chemical signals called pheromones for communication. These signals can be used to mark trails, signal danger, or attract mates. In some cases, insects may also use chemicals in their environment to communicate, such as by leaving scent marks.

Visual communication

Visual signals are another common method of insect communication. For example, fireflies use patterns of flashing lights to attract mates. Many butterflies and bees also use visual signals in mating displays, or to signal their toxicity to predators.

Auditory communication

Some insects use sound for communication. Male crickets and cicadas, for example, make distinctive sounds by rubbing their wings together to attract females. Larvae of certain moth species drum and scrape their mandibles or bodies against the substrates they inhabit, producing sounds that are used for communication.

Tactile communication

Many insects use touch to communicate. Ants often touch each other with their antennae to exchange information. Bees use a complex “waggle dance” to convey the location of a food source to their hive mates – the dance involves a combination of movements and vibrations.

Vibrational communication

Insects often use substrate-borne vibrational signals for communication. This form of communication is particularly prevalent in environments where visual and auditory cues are less effective, such as in the dark, underground, or underwater. Vibrational signals can serve various functions, including mate attraction, host location, and predator warning.

Thermal and humidity signals

Some insects can perceive and respond to changes in temperature and humidity. For example, honey bees use temperature signals for brood care and thermoregulation inside their colonies, and some insects can sense changes in humidity that might signal the onset of rain.

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