Chinese researchers have developed a nanoparticle-based formulation that combines an insecticide and a plant-derived repellent to provide longer-lasting control of HLB-spreading Asian citrus psyllids (ACP).
An article about their study, published in Nanomaterials, explores a way to extend pesticide effectiveness while reducing damage to citrus leaves. The article was written by Wenhua Rao, Qianying Li, Kaidi Wang, Chao Shen, Guocheng Fan and Jinfeng Hu with the Fujian Academy of Agricultural Sciences; Hua Chen with Ningde Inspection and Testing Centre for Agricultural Product Quality and Safety; and Lan Li with Fujian Provincial Center for Agri-Product Quality Safety Inspection and Testing.
The researchers used tiny, porous silica particles to carry imidacloprid — a commonly used insecticide — and fir essential oil, which repels ACP. The particles act like microscopic containers, gradually releasing both ingredients rather than allowing them to dissipate quickly.
Laboratory tests showed that the formulation released both ingredients more slowly than their unencapsulated counterparts. It also protected imidacloprid from ultraviolet light. After 72 hours of UV exposure, the formulation retained nearly 73% of its initial imidacloprid, compared with about 38% for the insecticide alone.
The combined formulation also repelled psyllids in laboratory tests. Following UV exposure, it provided greater insecticidal activity than unprotected imidacloprid during subsequent observations.
For citrus growers, the approach could eventually offer a way to extend psyllid suppression between applications while combining insect-killing and repellent effects. Longer-lasting protection could be particularly useful in integrated HLB management programs, where reducing psyllid feeding and movement helps limit disease spread.
The formulation also showed preliminary safety benefits. Unlike unencapsulated fir essential oil, which damaged citrus leaf tissue, the nanoparticle formulation caused no visible leaf injury in the tests. Researchers also found no significant adverse effects on Chinese milk vetch seed germination or earthworm survival under the tested conditions.
Field trials and longer-term environmental studies are needed to determine effectiveness in commercial groves, appropriate application rates and potential impacts on other organisms. The formulation is not yet a commercially validated replacement for existing psyllid management practices.
Read the full article here.
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