Domain:              Eukaryota
Kingdom:            Animalia
Phylum:               Arthropoda
Class:                   Insecta
Order:                   Lepidoptera
Family:                 Crambidae
Genus:                  Scirpophaga
Species:                S. incertulas

Binomial Name:   Scirpophaga incertulas (Walker, 1863)

Synonyms:           

Chilo incertulas Walker, 1863
Chilo incertellus Walker, 1917
Catagela admotella Walker, 1863
Schoenobius punctellus Zeller, 1863
Schoenobius minutellus Zeller, 1863
Tipanaea bipunctifera Walker, 1863
Chilo gratiosellus Walker, 1864
Schoenobius bipunctifer ab. quadripunctellifera Strand, 1918

Asia, Africa (Egypt), Europe (Spain), Oceania. It is recorded from Australia, Papua New Guinea [1]. It is found in Afghanistan, Nepal, north-eastern India, Sri Lanka, Bangladesh, Myanmar, Vietnam, Thailand, Malaysia, Singapore, Sumatra, Java, Borneo, Sumba, Sulawesi, the Philippines, Taiwan, China and Japan [5].

Host Range
Rice, cultivated and wild species [1].

Egg: The eggs are creamy white, flattened, oval and scale like and laid in mass and covered with buff coloured hairs

Larva: Full-grown larvae are pale yellow to yellowish green with a brown head and reach a length of 20 mm.

Pupa: White silken cocoons are found inside the stem.

Adult: The wingspan of the male is 18–22 mm and the female is 34 mm.[2] Adult males are smaller than the females. Males are brownish ochreous. Forewings irrorated (sprinkled) with dark scales and with the veins slightly streaked with fuscous. A black spot found at a lower angle of the cell. There is an oblique fuscous line runs from apex to vein 2. A marginal black specks series can be seen. Hindwings ochreous white. Female fuscous brown with pale fuscous hindwings.

Scirpophaga incertulas; previously known as Chilo incertulas. There are other Scirpophaga species on rice, and there has been confusion in the past in the identification of Scirpophaga incertulas, with males and females thought to be different species. A member of the Crambidae (snout moths) [1].

The rice yellow stem borer is the most common species in tropical wetland areas, and is a major pest of tropical lowland and deep-water rice. It attacks all stages of the crop [1]. Stem borers can destroy rice at any stage of the plant from seedling to maturity. They feed upon tillers and causes deadhearts or drying of the central tiller, during vegetative stage; and causes whiteheads at reproductive stage. The stem borer larvae bore at the base of the plants during the vegetative stage. On older plants, they bore through the upper nodes and feed toward the base [2].

The yellow stem borer is a pest of deepwater rice. It is found in aquatic environments where there is continuous flooding. Second instar larvae enclose themselves in body leaf wrappings to make tubes and detach themselves from the leaf and fall onto the water surface. They attach themselves to the tiller and bore into the stem.

Eggs are laid on the upper-surface (and upper half) of leaves in groups (average about 80) covered in tan scales from the female. Eggs hatch in 5-10 days, and the white larvae bore into the leaf sheath resulting in yellowish-white patches. Later, they invade the stem, and cause deadhearts or drying up of the central shoots (at the vegetative stage), and whiteheads (at the panicle stage). When fully grown (20-40 days) the larvae are pale-yellow to yellowish-green with a brown head, up to 20 mm long (Photo 4). After hatching, early instars bore into the leaf sheath and cause longitudinal yellowish-white patches as a result of feeding. Then it invades the stem of the rice plant and stays in the pith to feed on the inner surface of the stem wall. These are not externally visual as symptoms. Severe feeding causes a deep circular cut through the parenchyma tissue showing deadhearts at the vegetative stages and whiteheads at the reproductive stages. They pupate in white silk cocoons made in hollow stems at the base of the plant. In deep-water rice, the larvae and pupae may be beneath the water.

The larvae become dormant if dry periods occur or in seasons when rice is not grown. During rice-free times, the larvae remain in the stubble below the soil. Mortality is high (90%) during periods of dormancy, due to destruction of stubble, and possibly due to predation (spiders) and adverse environments (droughts).
The female moth has pale-yellow or light-brown forewings, each with a characteristic single, black spot. The smaller gray or light-brown male has two rows of small spots at the tip of each forewing. Females are 13 mm long with 32 mm wingspans.

They spread over short distances occurs as eggs on infested seedlings used for planting; as larvae that crawl from plant to plant and/or disperse on silken threads blown by the wind, as pupae in harvested stems, adults on the wing at night, and on farm machinery.

Among the stem borers infesting rice, the yellow stem borer is one of the most important pests throughout tropical South and Southeast Asia. To some extent, plants can compensate for the damage by producing more tillers or providing extra nutrients to those that survive, but they are still likely to suffer yield loss when more than one tiller is damaged per hill. In terms of the economics, CABI maintains that it is very difficult to translate the damage into economic impact, because many of the estimates of loss are from outbreak situations, and are not annual occurrences. Also, the estimates are not for the yellow stem borer alone.
Nevertheless, CABI estimates that damage by rice stem borers to be between 3 and 3.5%, and one third of that is due to the yellow stem borer alone. Using figures for rice production in tropical and sub-tropical Asia for 1999-2000, CABI estimates that the value of the lost grain is between US$1250 and US$1450 million. A considerable amount [1].

Look for the damage done by the yellow stem borer: deadhearts that can be easily pulled from the base of the plants during the vegetative stage, and whiteheards during the reproductive stage. Look for larvae (and frass) and pupae in the pulled-out stems to confirm the damage was caused by yellow stem borer. Look for small holes on the tillers.

Look for a yellowish-green moth with a characteristic single, black spot on each forewing. Because adults of several rice stem borers are similar, specimens should be checked by taxonomists with expertise in moth pests of rice.

In a nutshell:
Plants/Whole plant/dwarfing
Plants/Whole plant/dead heart
Plants/Stems/internal feeding
Plants/Leaves/wilting
Plants/Leaves/internal feeding
Plants/Leaves/abnormal colours

Check the field for the following damage symptoms:
   1. Deadhearts or dead tillers that can be easily pulled from the base during the vegetative stages
   2. Whiteheads during reproductive stage where the emerging panicles are whitish and unfilled or empty
   3. Tiny holes on the stems and tillers
   4. Frass or fecal matters inside the damaged stems
   5. Presence of brown coloured egg mass near leaf tip
   6. Larva bores into central shoot of paddy seedling and tiller, causing drying of the central shoot known as “dead heart”
   7. If infestation occurs in grown up plant, the whole panicle becomes dried and known as “white ear”
   8. Affected shoots and panicles could be easily pulled by hand

Deadhearts and whiteheads symptoms may sometimes be confused with damages caused by rats, neck blast, and black bug diseases.

To confirm stem borer damage, visually inspect rice crops for deadhearts in the vegetative stages and whiteheads in reproductive stages. Stems can be pulled and dissected for larvae and pupae for confirmation of stem borer damage.

Excessive boring through the sheath can destroy the crop. Its damage can reduce the number of reproductive tillers. At late infection, plants develop whiteheads [2].

Yellow stemborer damage can lead to about 20% yield loss in early planted rice crops, and 80% in late-planted crops.

BIOSECURITY
Countries not yet infested by the rice yellow stem borer should consider all likely pathways for entry, and apply quarantine measures accordingly. Many countries throughout Africa, the Americas, the Caribbean, and Oceania are at risk. Pathways of introduction are likely to be via produce contaminated by pieces of rice stem infested with larvae and/or pupae [1].

In a nutshell:
Use resistant varieties;
At seedbed and transplanting, handpick and destroy egg masses;
Raise level of irrigation water periodically to submerge the eggs deposited on the lower parts of the plant;
Before transplanting, cut the leaf-top to reduce carry-over of eggs from the seedbed to the field;
Ensure proper timing of planting and synchronous planting, harvest crops at ground level to remove the larvae in stubble, remove stubble and volunteer rice, plow and flood the field;
Encourage biological control agents: braconid, eulophid, mymarid, scelionid, chalcid, pteromalid and trichogrammatid wasps, ants, lady beetles, staphylinid beetles, gryllid, green meadow grasshopper, and mirid, phorid and platystomatid flies, bethylid, braconid, elasmid, eulophid, eurytomid and ichneumonid wasps, carabid and lady bird beetles, chloropid fly, gerrid and pentatomid bugs, ants, and mites, earwigs, bird, asilid fly, vespid wasp, dragonflies, damselflies, and spiders;
Bacteria and fungi also infect the larvae: mermithid nematode, chalcid, elasmid and eulophid;
Apply nitrogen fertilizer in split following the recommended rate and time of application.

ETL [6]

10% Dead heart symptoms 2% white ear symptoms.
   1. Clip the seedling tips before transplanting to eliminate egg masses.
   2. Install light trap @ 1 / ha and pheromone trap @ 5 / ac.
   3. Release egg parasitoid, Trichogramma japonicum @ 2cc /ac 3 times at weely interval.
   4. Spray Neem seed kernel extract 5% or Azadirachtin 0.03% 400 ml/ac.
   5. Spray any one of the following insecticides:
Acephate 75 % SP 267-400 g/ac
Carbofuran 3% CG 10 kg/ac
Carbosulfan 6% G 6.7 kg/ac
Carbosulfan 25% EC 320-400 ml/ac
CartapHydrochloride 50 % SP 400 g/ac
Chlorantraniliprole 18.5% SC 60 ml/ac
Chlorantraniliprole 0.4% G 4 kg/ac
Chlorpyriphos 20% EC 500 ml/ac
Fipronil 5% SC 400-600 g/ac
Fipronil 80%WG 20-25 g/ac
Flubendiamide 20% WG 50 g/ac
Flubendiamide 39.35% M/M SC 20 g/ac
Thiacloprid 21.7% SC 200 g/ac
Thiamethoxam 25% WG 40 g/ac

Before planting:
Handpick and destroy egg masses in the seedbed (nursery) beforer transplanting the field.
Before transplanting, cut the leaf-top to reduce carry-over of eggs from the seedbed to the field.
Choose short-stature, early-maturing varieties.
Prepare the land thoroughly ensuring vigorous plant growth when planted, and to destroy larvae and pupae from the previous crop.
During growth:
Try to synchronize planting in any area, avoiding overlapping crops and preventing pest populations moving from harvested to standing crops. Additionally, choose varieties with similar times to maturity.
If the crop is seasonal, plant early. Two early-maturing crops may be less damaged than a single late-maturing variety.
Raise level of irrigation water periodically to submerge any eggs deposited on the lower parts of the plant.
Weed as soon as required to promote good crop growth.
Cut out the stems with deadhearts and remove them from the field. Destroy the larvae or burn the stems. Note, this is labor intensive and not very effective as the pest may already have left the stem.
Split applications of nitrogen fertilizer. High nitrogen application favors build-up of stem borers.
After harvest:
Harvest crops at ground level to remove the larvae and pupae in the stubbles.
Plough remaining rice stubble into the soil to kill larvae and pupae, and avoid leaving unharvested or volunteer plants. Irrigate the field, if that is possible at this time.

Planting or seeding times may be delayed to avoid the peak emergence of moths from the diapausing population, but fields planted later than neighboring fields may suffer high late season damage [7].

Rice seedbeds may be used as a trap crop for moths emerging from diapause; moths may be collected by sweep nets and egg masses may be collected by hand or leaf clipping. Thorough tillage followed by flooding after harvest may severely reduce the population of S. incertulas, resulting in low incidence in the next crop [7].

The use of sex pheromone may also reduce the borer population (Ganeswara Rao et al., 1994). Season-long control of S. incertulas by pheromone found as effective as insecticides (Cork and Hall, 1998) [7].

In Bangladesh, light traps placed outside the rice field are used for controlling S. incertulas (Anon., 1999). The collection and destruction of egg masses are also suggested methods of control in Bangladesh [7].

NATURAL PREDATORS
In biological control, egg parasitism is high and widespread. Species of the three genera Telenomus, Tetrastichus and Trichogramma are greatly effective against eggs, larva and adult moths.[5]

Conocephalus longipennis, a bush cricket is known to consume moth eggs. Other than insect parasitoids, fungi, bacteria, viruses and mermithid nematodes are also used for Integrated Pest Management (IPM) [5]. Split release of Trichogramma japonicum improved control in Nagaland, India [5]

Many egg parasitoids have been identified with Telenomus spp., Tetrastichus spp., and Trichogramma spp. being the most common. There are also predators of eggs, e.g., long-horned grasshoppers, and adults are vulnerable to spiders. Every effort should be made to preserve this fortunate situation. Only apply pesticides as a last (and not a first) resort.
To see if chemical control is needed, count the number of eggs that are parasitised, as follows:
Count number of egg masses on 20 hills observed at random diagonally across the field
The economic threshold is:
2 or more egg masses up to panicle initiation stage, OR
1 egg mass thereafter
Collect the egg masses and put them in vials or jars.
If more parasitoids emerge than larvae: DO NOT SPRAY.
If more larvae emerge than parasitoids: SPRAY.
Carry on monitoring.

The Economic Threshold in Bangladesh is 3 egg masses or 10-15% deadhearts.

RESISTANT VARIETIES
Most of the modern semi-dwarf rice varieties now grown by farmers have a moderate level of resistance to stem borers, but efforts to produce highly resistant varieties through conventional breeding and wide hybridization with wild rice species have not been successful, but research continues. Genetic modification of varieties with crystal toxin genes from Bacillus thuringiensis has been done, but release is still under consideration.

More than 39,000 varieties of rice have been screened against S. incertulas at the International Rice Research Institute in Laguna, Philippines (Khan et al., 1991). ASD16, ASD20, Birsa Dhan 201, Chandina, Chianan 2, Co45, CR 712-3-38, IR36, IR72, IRSA69, IRSA76, Majhera 7, Paichung 16, Ptb 10, Ratna, Su Yai 20, TKM 6, TNAU90012, TNAU90094 and WC1263 were moderately resistant to S. incertulas (Khan et al., 1991; Mishra et al., 1996; Ramaraju and Velusamy, 1997; Shanmugasundaram et al., 1997; Singh and Pandey, 1997; Singh et al., 1996) [7].
However, several wild rice species have been identified with high levels of resistance which is polygenic in nature. Attempts to upgrade the level of S. incertulas resistance in cultivated rice is an active area of research [7].

Genetic engineering of rice with toxins from Bacillus thuringiensis is being pursued by numerous research groups, and S. incertulas is a major target of this work (Bottrell et al., 1992). The Cry1Aa, Cry1Ab, Cry1Ac and Cry2A proteins of Bacillus thuringiensis are highly toxic to S. incertulas (Alam et al., 1999; Maqbool et al., 1998; Cheng et al., 1998; Datta et al., 1998; Alam et al., 1998; Ghareyazie et al., 1997; Nayak et al., 1997; Wunn et al., 1996) [7]. Transgenic rice developed by transformation of rice plants by particle bombardment with a truncated version of one or more of these synthetic genes from Bacillus thuringiensis are highly lethal to S. incertulas larvae. However, the development of a transgenic rice variety and its adoption in the field is still a debatable issue.

Applications of Chlorantraniliprole at 40 g.a.i./ha was found to be efficacious against S. incertulas.

The use of insecticides risks destroying natural enemies, and some products recommended for this and other stem borers are extremely toxic and risk harm to users and the environment (e.g., carbofuran, monocrotophos and phorate). Three others commonly recommended insecticides – diazinon, chlorpyrifos and fipronil – are all classified by WHO as Class II moderately hazardous pesticides. They are broad-spectrum insecticides. In addition, fipronil is highly toxic to fish, and it has been associated with colony collapse disorder of bees.

If insecticides are required as a ‘last resort’ action, consider using biorational products, for instance:

Bt, the toxin from a bacterium, Bacillus thuringiensis.

Abamectin, a natural fermentation product from an actinomycete, Streptomyces avermitilis.
Spinosad, chemical products from a bacterium, Saccharopolyspora spinosa.

The present investigation suggests that the bioactivator thiamethoxam when employed as a seed treatment plays a critical role in rice growth and development [8].

No information found

No information found

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5592929/

https://www.cambridge.org/core/journals/bulletin-of-entomological-research/article/abs/impact-of-yellow-stemborer-scirpophaga-incertulas-walker-lepidoptera-pyralidae-on-deepwater-rice-with-special-reference-to-bangladesh/9C1FB45B9B17D3B280EA6CF9E5693D6C

https://www.cambridge.org/core/journals/bulletin-of-entomological-research/article/abs/control-of-yellow-stem-borer-scirpophaga-incertulas-lepidoptera-pyralidae-by-mating-disruption-on-rice-in-india-effect-of-unnatural-pheromone-blends-and-application-time-on-efficacy/D756576D98EA6D6C7282FB4B9E7494B9

https://academic.oup.com/jee/article-abstract/98/4/1179/883456

https://www.tandfonline.com/doi/abs/10.1080/09670870400028276

https://link.springer.com/article/10.1007/s12633-022-01897-z

https://gender.cgiar.org/publications/control-yellow-stem-borer-scirpophaga-incertulas-mating-disruption-pvc-resin

https://www.gov.uk/research-for-development-outputs/control-of-the-yellow-stem-borer-scirpophaga-incertulas-by-mating-disruption-with-a-pvc-resin-formulation-of-the-sex-pheromone-of-chilo-suppressalis-lepidoptera-pyralidae-in-india

https://bioone.org/journals/environmental-entomology/volume-35/issue-4/0046-225X-35.4.1094/Feeding-Patterns-of-iScirpophaga-incertulas-i-Lepidoptera–Crambidae-on/10.1603/0046-225X-35.4.1094.short

https://jurnal.ugm.ac.id/jpti/article/view/37535

https://onlinelibrary.wiley.com/doi/epdf/10.1111/jen.12324

https://www.sciencedirect.com/science/article/abs/pii/S026121942030404X

https://www.sciencedirect.com/science/article/abs/pii/S2352215119300017

https://onlinelibrary.wiley.com/doi/epdf/10.1111/jen.12747

https://www.tandfonline.com/doi/abs/10.1080/15569543.2020.1855654

https://apps.lucidcentral.org/pppw_v11/text/web_full/entities/rice_yellow_stem_borer_533.htm
http://www.knowledgebank.irri.org/training/fact-sheets/pest-management/insects/item/stem-borer
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8234988/
https://academic.oup.com/g3journal/article/7/9/3031/6027564
https://en.wikipedia.org/wiki/Scirpophaga_incertulas
https://agritech.tnau.ac.in/crop_protection/rice/crop_prot_crop_insectpest%20_cereals_paddy_m1.html
https://plantwiseplusknowledgebank.org/doi/full/10.1079/pwkb.species.49009
https://www.sciencedirect.com/science/article/abs/pii/S0885576517301212