Identifying and Managing Sap Sucker Pests in Mulberry Cultivation

Mulberry (Morus alba L.) is the sole food plant of the silkworm (Bombyx mori L.), and the quality of its leaves directly determines the quality of silk produced. Yet, mulberry cultivation faces a persistent threat from a group of small but destructive insects known as sap suckers. These pests pierce plant tissue and drain the sap, degrading leaf nutritive value, reducing yield, and ultimately impacting sericulture productivity. Research has estimated that insect pest damage causes an average leaf yield loss of around 4,500 kg per hectare per year in mulberry gardens. Understanding who these pests are, what damage they cause, and how to manage them effectively is essential for every mulberry grower.

What are sap sucker pests? 🔗

Sap suckers are insects equipped with piercing and sucking mouthparts. Rather than chewing leaf tissue, they insert their stylets into the plant and extract the cell sap. In mulberry, the four primary sap-sucking pests are the mealy bug (Maconellicoccus hirsutus), thrips (Pseudodendrothrips mori), jassid (Empoasca flavescens), and spiralling whitefly (Aleurodicus dispersus). Each belongs to a different insect family, but all share the same feeding behaviour and cause significant qualitative and quantitative losses in mulberry foliage. Studies confirm that feeding by these pests disrupts normal metabolic activities in the plant, leading to biochemical and nutritional changes in the leaf that make it less suitable for silkworm rearing.

Mealy bug (Maconellicoccus hirsutus) 🔗

The pink mealy bug is considered one of the most economically damaging sap suckers in mulberry cultivation. It belongs to the family Pseudococcidae under the order Hemiptera. According to research published in Discover Agriculture, M. hirsutus has been recorded on over 346 host plant species, but its damage in mulberry is particularly severe because chemical pesticide use is restricted – any residues on the leaves can harm the silkworms that feed on them.

Life cycle 🔗

Each adult female deposits 350-500 orange, elongated eggs in a loose cottony mass called a terminal ovisac. Eggs hatch in 5-10 days depending on temperature. The emerging crawlers (nymphs) are also orange-coloured and covered in a mealy, waxy substance. Females pass through three nymphal instars and males through four, with the nymphal period lasting approximately 25-26 days. Adult males mate but do not feed, dying within 2-3 days. Adult females can reproduce parthenogenetically.

Damage and symptoms 🔗

The mealy bug causes a distinctive condition in mulberry plants locally called “Tukra”. The condition is characterised by the crinkling and darkening of leaves at the apical portions of the shoot, producing brittle, malformed growth. The leaf yield is severely reduced and the remaining leaves are depleted of nutritive value, making them unsuitable for silkworm feeding. Infestations are most intense during summer months and recur during both pre-monsoon and post-monsoon periods.

Thrips (Pseudodendrothrips mori) 🔗

Mulberry thrips belong to the family Thripidae under the order Thysanoptera. They are tiny insects – adults measure only about 0.9 mm in body length – but their collective feeding causes visible and significant leaf damage.

Life cycle 🔗

Adult females are dark brown in colour, while males are brownish yellow. A single female lays 30-50 bean-shaped, yellow eggs on the underside of leaves. Eggs hatch in 6-8 days, producing pale yellow nymphs that moult four times over 15-18 days. Adults possess the characteristic fringed wings typical of the Thysanoptera order.

Damage and symptoms 🔗

Thrips rasp the leaf surface and suck the exuding sap. The affected leaves develop a silvery or bronzed appearance, and heavily infested leaves may curl or become wrinkled. Thrips infestations occur throughout the year but are particularly severe during summer months. Research on ecofriendly management of P. mori has demonstrated that feeding thrips-infested leaves to silkworms negatively affects rearing performance and cocoon quality.

Jassid (Empoasca flavescens) 🔗

Jassids, also known as leafhoppers, belong to the family Cicadellidae under the order Hemiptera. They are small, pale green insects measuring 2.5-4 mm in body length. Adults and nymphs are notably agile and move sideways when disturbed – a characteristic that makes them harder to spot during field scouting.

Life cycle 🔗

Adult females lay pale yellow eggs singly on the underside of leaves, inserting them just below the leaf epidermis. Eggs hatch in 4-9 days. Nymphs are also pale green and moult four times before reaching adulthood. Pupation takes place on the leaf itself, making the entire life cycle confined to the plant canopy.

Damage and symptoms 🔗

Both nymphs and adults of jassid feed by sucking sap from the leaf margin and underside. The characteristic damage is known as “hopper burn” – the leaf margins first turn yellow, then curl downward and gradually turn brown from the tips inward. In severe infestations, the plant exhibits a scorched appearance. As documented in mulberry pest research, jassid feeding causes significant chlorosis and suppresses the photosynthetic capacity of the leaf, directly reducing its nutritive value for silkworms.

Spiralling whitefly (Aleurodicus dispersus) 🔗

The spiralling whitefly is an invasive pest native to the Caribbean region and Central America. It is believed to have entered India via Sri Lanka or the Maldives and was first reported in Kerala in 1993, subsequently spreading throughout peninsular India. It belongs to the family Aleyrodidae under the order Homoptera and is considered highly polyphagous, having been recorded on over 253 host plant species. Its common name comes from its habit of laying eggs in a characteristic spiral pattern on the leaf surface.

Life cycle and occurrence 🔗

Both nymphs and adults of A. dispersus form colonies on the underside of leaves. The pest is present throughout the year in South India, with populations peaking during summer months (March-June) when temperatures are high and humidity is relatively low. Populations drop significantly in cooler winter months. Studies on whiteflies in sericulture confirm that population build-up is positively correlated with temperature.

Damage and symptoms 🔗

The spiralling whitefly causes damage through direct sap removal and indirectly through the secretion of honeydew, a sticky sugary substance that coats the leaf surface and promotes the growth of black sooty mould. This fungal growth further reduces the photosynthetic efficiency of the leaf. Research has shown that every 1% of leaf area damaged by spiralling whitefly results in a reduction in cocoon yield of approximately 2.08 kg – a figure that underlines the economic stakes of even moderate infestations. Severely affected plants show chlorosis, premature leaf fall, and stunted growth.

Management strategies for sap sucker pests in mulberry 🔗

Effective management of sap suckers in mulberry requires an integrated approach. Because mulberry leaves are fed directly to silkworms, chemical use must be carefully timed and restricted to compounds with defined safety periods to avoid residue toxicity to the silkworms.

Mechanical and cultural control 🔗

For mealy bug, the most immediate step is the removal and destruction of infested shoots by pruning and burning. This directly reduces the pest population and prevents the spread of Tukra disease to healthy portions of the garden. Sprinkler irrigation is particularly effective against thrips – the water jet physically disperses nymphs and adults from the leaf surface and, as a side benefit, washes off dust deposits that can inhibit photosynthesis. Comparative field studies have demonstrated that water jetting at 15 and 25 days after pruning can perform at par with chemical sprays for certain sucking pests including jassids, while being entirely safe for beneficial insects.

Chemical control 🔗

When pest populations exceed economic thresholds, chemical intervention becomes necessary. Key recommendations include:

• Mealy bug: Spraying 0.01% parathion with a safe period of 13 days before the next leaf harvest.
• Thrips: Spraying 0.02% DDVP (dichlorvos) twice at weekly intervals; safe period of 7 days.
• Spiralling whitefly: The Central Silk Board of India recommends foliar spray of 0.02% monocrotophos at 15 and 30 days after pruning, with a safe period of 15 days.
• Jassid: Dimethoate at 0.05% has been found effective and is among the standard recommendations for jassid control in mulberry.

Strict adherence to safe periods is non-negotiable in mulberry – leaves must not be harvested for silkworm feeding until the specified waiting period has elapsed after any pesticide application.

Botanical and bio-based control 🔗

Given the restrictions on synthetic chemicals in mulberry ecosystems, botanical and bio-based approaches have gained considerable attention. Studies have shown that neem seed kernel extract (NSKE) at 4% concentration offers up to 97% repellence against mealy bug nymphs, making it one of the most effective botanical options. Pongamia and Lantana leaf extracts have also shown promising repellency. For spiralling whitefly, neem-based formulations have proven effective while remaining safe for natural enemies.

Biological control 🔗

Biological control is arguably the most sustainable strategy for sap sucker management in mulberry, though it requires careful selection of bioagents to ensure they pose no threat to silkworms. The most well-known predator used is Cryptolaemus montrouzieri, commonly called the mealybug destroyer – a coccinellid (ladybird beetle) that is released in mulberry gardens to prey on mealy bug colonies. Research on the biology and invasiveness of M. hirsutus confirms that this pest is commonly suppressed in many regions through the introduction of natural enemies, particularly when the pest has invaded new areas without its native predators present.

For spiralling whitefly, the parasitoid wasps Encarsia guadeloupae and related Encarsia species have been fortuitously introduced alongside the pest into India and are known to exert natural suppression in certain areas. Surveys for natural enemies of A. dispersus in India have identified several indigenous predators including coccinellids and neuropteran insects that contribute to population regulation.

Emerging research is also exploring fungal-based management. A 2025 study published in Discover Agriculture found that enzyme extracts from Aspergillus fumigatus can degrade the protective waxy coating of mealy bug nymphs, achieving complete mortality in eggs and first-instar larvae within 24 hours of treatment – a promising avenue that avoids the chemical residue problem entirely.

Why integrated management matters in sericulture 🔗

The unique challenge in mulberry pest management is that the crop is not the final product – it is the food for silkworms, which are themselves the production unit. Every pesticide applied, every biological agent released, and every cultural practice adopted must be evaluated not only for its effect on the pest, but also for its safety to Bombyx mori. This makes an Integrated Pest Management (IPM) approach – combining cultural, mechanical, botanical, biological, and judicious chemical methods – not just preferable but essential. Routine field scouting for early detection, timely pruning, maintaining appropriate plant spacing to reduce humidity in the canopy, and strict observation of pesticide safety periods form the backbone of any sound sap sucker management programme in mulberry gardens.

What do you think? Given that chemical use in mulberry is constrained by silkworm safety concerns, do you think botanical and biological controls alone can adequately protect mulberry gardens from sap sucker infestations at a commercial scale? And with invasive pests like the spiralling whitefly continuing to spread, how should sericulture regions adapt their pest management frameworks to respond to new threats faster?

References

1. https://scialert.net/fulltext/?doi=ajbs.2018.41.52
2. https://link.springer.com/article/10.1007/s44279-025-00341-1
3. https://www.researchgate.net/publication/334837491_Ecofriendly_management_of_Pseudodendrothrips_mori_Niwa_and_its_impact_on_abundance_of_predatory_coccinellids_in_mulberry_ecosystem
4. https://www.researchgate.net/publication/258240632_Management_of_spiraling_whitefly_Aleurodicus_dispersus_Russel_in_guava_Psidium_guajava_L
5. https://www.researchgate.net/publication/227711291_Biocoenology_and_control_of_whiteflies_in_sericulture
6. https://silks.csb.gov.in/gaya/wp-content/themes/Common_District/gaya/dpm-frame.html
7. https://www.journalijdr.com/evaluation-botanical-extracts-repellency-property-against-pink-mealy-bug-maconellicoccus-hirsutus
8. https://link.springer.com/article/10.1007/s10340-013-0512-z