Preventing and Managing Root/Shoot Feeding Pests in Mulberry

Mulberry cultivation is the backbone of sericulture, providing the sole food source for silkworms. But while most growers worry about leaf-eating insects, a group of pests works silently below and within the plant – boring through stems, colonizing root systems, and feeding underground for months before visible damage appears. These are the root and shoot feeders: the stem borer (Apriona spp.), subterranean termites (Odontotermes spp.), and the May-June beetle (Holotrichia serrata). Together, they represent one of the most destructive pest categories in mulberry farming, and understanding them is essential for protecting both the plant and the silk industry that depends on it.

What makes root and shoot feeders so dangerous? 🔗

Unlike sap-sucking or leaf-eating pests whose damage is immediately visible, root and shoot feeders attack the structural core of the mulberry plant. They compromise the vascular system – the network of tissues that transports water and nutrients – long before the farmer notices anything is wrong. By the time wilting, yellowing, or plant collapse occurs, the internal damage is often severe and difficult to reverse. These pests tend to be most active during the monsoon and post-monsoon seasons, when soil moisture and humidity favor their reproduction and movement. Their hidden nature makes early identification and preventive management critical.

Stem borer (Apriona spp.) 🔗

The stem borer is one of the most destructive mulberry pests across South and Southeast Asia. Belonging to the longhorn beetle family Cerambycidae, Apriona species are large insects – adults typically measure 25-40 mm in length with characteristic long antennae. According to EPPO quarantine pest datasheets, the primary hosts of Apriona germari include plants from nineteen families, with mulberry (Morus spp.) among the most frequently attacked.

Life cycle and behavior 🔗

Adult beetles emerge primarily during the monsoon season. Females lay eggs in bark crevices or deliberately created notches on the stem surface – a visible oviposition scar often signals an early infestation. Once eggs hatch, larvae immediately begin boring into the stem, creating long tunnels through the woody tissue. Research from Jammu and Kashmir reports that adult populations of Apriona germari in subtropical regions peak in mid-July. The larval stage can persist for many months as grubs hollow out the interior of stems and branches.

Symptoms of infestation 🔗

The most recognizable symptom is the presence of circular entry holes in the stem, typically 6-8 mm in diameter, surrounded by frass – the sawdust-like excrement pushed out by feeding larvae. Shoots above the damaged area begin to wilt and dry up, and severely infested plants may collapse entirely. A key identification feature noted in EPPO documentation on Apriona cinerea is that regular frass expulsion holes make this species comparatively easier to locate than other borers.

Management 🔗

Mechanical control is the first line of defense. Locate active borer holes identified by fresh frass deposits and use a stiff wire or needle to probe and kill larvae inside the tunnels. Adult beetles, which are nocturnal, should be collected and destroyed when spotted. Heavily infested branches should be pruned and removed from the field immediately. Studies in India demonstrated that removal of heavily infested “brood trees” reduced borer infestation by nearly 60%, and summer pruning also significantly cut infestation rates.

Chemical control involves injecting a Chlorpyriphos solution directly into the borer holes using a syringe, then sealing the hole with clay or wax. This ensures the insecticide reaches larvae deep inside tunnels. Alternatively, stem surfaces can be sprayed with Chlorpyriphos during peak egg-laying periods. eSilk management guidelines also recommend pouring petrol, kerosene, or chloroform into holes, or plugging them with cotton wool soaked in carbon bisulphide, as effective fumigation methods.

Light traps placed in the plantation during the adult emergence period are a useful preventive tool, attracting and capturing nocturnal adult beetles before they can lay eggs. Avoid planting mulberry near apple orchards or stands of poplar and willow, as Apriona species readily move between these hosts.

Termites (Odontotermes spp.) 🔗

Odontotermes is a genus of subterranean, fungus-growing termites widespread across tropical Asia and Africa. Research published in the International Biodeterioration & Biodegradation journal identifies the major mound-building pest species in India as Odontotermes obesus, O. redemanni, and O. wallonensis. These social insects build large underground colonies and construct mud tubes to access above-ground plant parts while remaining protected from the environment.

How termites damage mulberry 🔗

Termite workers consume the cellulose in mulberry roots and lower stem tissue, hollowing out the plant from below. They preferentially attack stressed, recently transplanted, or poorly drained plants. Damage typically starts at soil level and progresses upward. The US EPA notes that most termite damage goes undetected until significant structural harm has already occurred, because termites rarely emerge from soil or their mud tubes.

Symptoms 🔗

Key warning signs include mud tubes on the stem surface near the soil line, wilting and yellowing of leaves despite adequate soil moisture, stunted or declining plant growth, and hollow stems near the base. Severely affected young plants can often be pulled out of the ground with minimal resistance due to complete root destruction.

Management 🔗

Mechanical control includes physically destroying termite mounds found near the mulberry plantation and removing dead wood, crop debris, and organic matter that serve as food sources for termite colonies. Flooding suspected areas can disrupt underground colonies.

Chemical soil treatment is the primary control method. A study on Odontotermes brunneus found that Chlorpyriphos was among the most effective insecticides against termites. Soil drenching with a Chlorpyriphos solution around the root zone creates a chemical barrier that kills workers on contact. Pre-planting soil treatment in termite-endemic areas is strongly recommended as a preventive measure. Pest management guidance advises targeted soil termiticide application around nests and regular field monitoring in agricultural zones.

May-June beetle / White grub (Holotrichia serrata) 🔗

Holotrichia serrata, commonly known as the May-June beetle or white grub, is a scarabaeid beetle whose larvae are a serious root pest of mulberry and many other crops. A review published in Agricultural Reviews confirms that H. serrata is among the polyphagous root grubs recorded from mulberry-growing regions of India, alongside coconut, groundnut, and sugarcane cropping systems.

Life cycle 🔗

Adult beetles emerge from the soil during May and June, typically triggered by the first monsoon or pre-monsoon showers. They are nocturnal and strongly attracted to light sources. Adults feed on the foliage of host trees – including neem, Ziziphus, and Acacia species – for a period before mating. Females then return to the soil to lay eggs. The C-shaped, cream-colored larvae that hatch spend 8-10 months feeding underground on mulberry roots, making them difficult to detect and control once established. According to CABI’s Plantwise Knowledge Bank, white grubs are soil-dwelling root feeders whose grubs cause yellowing, and infested plants wilt and can be easily uprooted.

Symptoms 🔗

The above-ground signs of white grub damage are often mistaken for drought stress or nutrient deficiency. Affected plants show gradual yellowing and wilting, reduced growth, and a noticeable decline in vigor. Annuals may collapse suddenly, while perennial mulberry plants show a slower decline over time – reduced yield and shortened lifespan – before the problem is traced to root damage. Digging around the base of a declining plant will reveal the larvae feeding in the root zone.

Management 🔗

Mechanical control of adult beetles during emergence is highly effective and economical. Hand collection of beetles from host trees in the evenings – when adults congregate for feeding and mating – has been practiced at a large scale in India. Light traps installed in or near the plantation during May-June are particularly useful for capturing adults in significant numbers before egg-laying begins.

Cultural control through deep ploughing of the soil in May and June exposes larvae and pupae to heat, desiccation, and predatory birds. Flooding the soil around affected plants can also reduce grub populations. Removing weeds eliminates alternative food sources and reduces habitat suitability for the pest.

Chemical control targets the larval stage in the soil. Multiple studies recommend soil drenching with Chlorpyriphos around the root zone as effective for managing white grub populations in the field. For adult beetles, spraying host trees with carbaryl during peak emergence periods reduces the adult population available to lay eggs.

Biological control is increasingly viable. Research on sugarcane showed that soil application of Metarhizium anisopliae-enriched farmyard manure reduced H. serrata grub populations by 86-89%, outperforming chemical treatments. The entomopathogenic fungus Beauveria bassiana has also shown efficacy against white grub larvae and can be integrated into a broader IPM strategy for mulberry plantations.

Integrated prevention: key practices across all three pests 🔗

Managing root and shoot feeders effectively requires a combination of practices rather than reliance on a single method. Across all three pests, the following preventive measures are consistently recommended:

• Pre-planting soil treatment with Chlorpyriphos in areas with a history of termite or white grub infestation helps eliminate soil-stage pests before the crop is established.
• Light traps deployed during adult emergence periods (especially May-July) reduce populations of stem borer adults and May-June beetles before they can reproduce.
• Regular field inspection – checking for borer holes with frass, mud tubes at the stem base, or unexplained wilting – enables early intervention before damage becomes severe.
• Sanitation pruning: removal and destruction of infested branches and dead plant material eliminates breeding sites and reduces carry-over populations.
• Avoid plant stress: well-maintained, vigorous mulberry plants are significantly more resilient to all three pests. Proper irrigation, drainage, and nutrition reduce susceptibility, particularly to termite attack.

Root and shoot feeding pests are a persistent challenge in mulberry cultivation precisely because their damage develops out of sight. The most effective growers are those who combine regular monitoring with timely mechanical and chemical interventions – and who treat prevention as seriously as cure.

What do you think? Given that root and shoot feeders cause damage that often goes undetected until it becomes severe, how practical is it for smallholder mulberry farmers to implement regular underground monitoring? And with biological agents like Metarhizium anisopliae showing strong results against white grubs, should sericulture extension programs prioritize these alternatives over conventional Chlorpyriphos-based treatments?

References

1. https://onlinelibrary.wiley.com/doi/10.1111/epp.12127
2. https://www.researchgate.net/publication/290601712_Cultural_control_of_Apriona_germari_Hope_Coleoptera_Cerambycidae_Lamiinae_infesting_mulberry_plants_in_Jammu_and_Kashmir_India
3. https://onlinelibrary.wiley.com/doi/10.1111/epp.12126
4. http://www.esilk.net/esilken/newsen_show.aspx?id=5110
5. https://www.sciencedirect.com/science/article/abs/pii/S0964830509001474
6. https://www.epa.gov/safepestcontrol/termites-how-identify-and-control-them
7. https://www.researchgate.net/publication/332331229_Effect_of_cypermethrin_on_worker_and_soldier_termites_of_subterranean_termites_Odontotermes_brunneus_Hagen_Termitidae_Isoptera
8. https://www.pestmanglobal.com/solution/4-species-of-termites-that-pest-control-companies-must-know-coptotermes-reticulitermes-odontotermes-macrotermes/
9. https://arccjournals.com/journal/agricultural-reviews/R-2310
10. https://plantwiseplusknowledgebank.org/doi/full/10.1079/pwkb.species.29633
11. https://www.researchgate.net/publication/346327609_Biological_control_of_white_grubs_Holotrichia_serrata_Fabricius_in_sugarcane_by_two_species_of_entomopathogenic_fungi_Metarhizium_anisopliae_and_Beauveria_bassiana