A naturally occurring predatory soil mite may one day become another tool for helping citrus growers manage citrus nematodes without relying solely on chemical controls. That’s according to a new study published in the journal Biology by Mahmoud M. Al-Azzazy and Suloiman M. Al-Rehiayani of the Department of Plant Protection, College of Agriculture and Food at Qassim University in Saudi Arabia.
The researchers evaluated the predatory soil mite Androlaelaps casalis as a biological control agent against the citrus nematode (Tylenchulus semipenetrans) and the root-knot nematode (Meloidogyne incognita). The citrus nematode is responsible for “slow decline” disease and is estimated to reduce citrus yields worldwide by 15% to 30%, making it one of the industry’s most economically important pests.
In laboratory trials, the researchers found that A. casalis successfully completed its life cycle while feeding on juvenile citrus nematodes and juvenile root-knot nematodes. Females reproduced well on both prey types, laying nearly 49 eggs when feeding on citrus nematodes and about 47 eggs when feeding on root-knot nematodes. More than 94% of the predatory mites survived to adulthood when feeding on juvenile nematodes, demonstrating that these pests are an excellent food source for the beneficial mite.
The study also showed the predator has an impressive appetite. During its lifetime, a single female A. casalis consumed an average of more than 4,400 citrus nematode juveniles and more than 3,800 root-knot nematode juveniles under laboratory conditions. However, the mites were much less successful when feeding only on root-knot nematode egg masses, indicating they are far more effective against juvenile nematodes than eggs.
For citrus growers, these findings point to the potential for biological control as another tool in an integrated nematode management program. A naturally occurring predator that can suppress citrus nematodes could help reduce dependence on chemical nematicides while supporting healthier soil ecosystems.
That said, growers should view these results as promising — not practice-changing. The experiments were conducted under controlled laboratory conditions with consistent temperatures, humidity and abundant prey. As the study’s authors note, additional greenhouse and field trials are needed. Further research could determine whether A. casalis can establish, survive and provide meaningful nematode suppression under commercial grove conditions, where environmental conditions are far more variable.
If future field trials confirm these laboratory results, A. casalis could become another valuable component of sustainable citrus nematode management, giving growers an additional option for protecting tree health and maintaining productivity.
See the full article, Biocontrol Potential of Androlaelaps casalis Against Two Key Phytoparasitic Nematodes: Tylenchulus semipenetrans and Meloidogyne incognita, here.
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