Hiding as if in a Trojan horse, wheat stem sawfly larvae chew inside wheat stems and sometimes pose problems for prairie farmers.
When technology is developed to predict the danger, farmers will find it easier to decide whether pest control treatments may be warranted. As a first step, United States Department of Agriculture scientists in Peoria, Illinois, have discovered and synthesized some of the natural odours that attract adult sawflies of one gender to another.
Whether or not such odours may one day be used in trap baits to monitor sawfly populations, the discoveries may lead to more novel approaches to limiting sawfly damage.
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The scientists focus their research on adult sawflies because insecticide spraying has little effect once the sawfly eggs are laid and the larvae are feeding safely within wheat stems.
One of the sawfly’s own antennae, suspended between tiny electrodes, provides a main platform for the research that makes use of a technique called coupled gas chromatographic-electroantennographic detection, or GC-EAD.
In response to odours, the antenna sends out electrical signals to help scientists pinpoint exactly the few chemicals that are critical to the sawfly’s behaviour. The information helps researchers identify various mixes of volatile chemicals to research the insect’s behaviour in a laboratory wind tunnel or in the field.
In other research, the Peoria scientists are using GC-EAD to discover attractants for exotic flea beetles that are being used as biological control agents against leafy spurge, flea beetles that are pests of canola and other cruciferous crops, sap beetles that are pests of figs, dates, and corn, other sap beetles that spread a fungus that infects trees causing oak wilt, and exotic leaf beetles that may someday control weedy tamarisk trees.
