Insects rely heavily on chemical signals probably more than on any other form of communication. These signals, called semiochemicals or infochemicals, serve as a "language" that mediates interactions between organisms. Insects may be highly sensitive to low concentrations of these chemicals. At the University of California, Riverside, entomologists and chemists have developed a technique for replicating complex chemical mixtures of the chemical signals insects use to communicate. This development could result in new "green" methods for controlling pest like ants by disrupting the organization of their colonies. Most insects use chemical signals for communicating with species and sex. Social insects such as ants living in colonies also differentiate castes (workers, queens, and drones) based on chemical cues. Insects employ their sense of taste or smell in order to detect the presence of semiochemicals. Specialized receptors may be located anywhere on the body, but are commonly found on the feet, antennae, palps, and ovipositor. "Insects that live in large colonies, such as ants and bees, these chemicals have additional functions," said co-author Jocelyn G. Millar. "The queen in these colonies, for example, uses the chemicals to prevent her workers from laying eggs of their own and ensuring that she remains the only reproducing female in the colony." The researchers devised a technique that allowed them to isolate 36 pure hydrocarbon molecules from the complex chemical blends of 20 randomly-chosen insect species. After the compounds could be conclusively identified, the effects of the individual chemicals could be tested. Their technique is described in the Proceedings of the National Academy of Sciences. If these chemicals could be isolated, they could utilized to enhance pest control efforts and may one day replace insecticides. However, isolating these chemicals and determining their absolute configurations and functions has been challenging because the chemicals occur in complex mixtures which are hard to separate.