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Rice leaf folder
পরিচিতি
Cnaphalocrocis medinalis, the rice leafroller, is a species of moth of the family Crambidae. The moth is very active, bright yellow or straw in colour with two distinct wavy lines in the fore wing and one wavy distinct line in the hind wing. The larvae are considered a pest of Oryza sativa, Zea mays, and Triticum, Saccharum and Sorghum species.
English name Rice leaf folder
Bangla name পাতা মোড়ানো পোকা
বৈজ্ঞানিক নাম Cnaphalocrocis medinalis
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera
Family: Crambidae
Genus: Cnaphalocrocis
Species: C. medinalis
It is found in south-east Asia, including Hong Kong, Sri Lanka, Taiwan, Thailand and most of Australia.
পোষক পরিসীমা
Considered a pest of Oryza sativa, Zea mays, and Triticum, Saccharum and Sorghum species.
Adult moths are medium-sized (8-10 mm long and 16-20 mm wing expanse). They are light brown with shiny, brownish yellow wings adorned with dark, broad margins and 2-3 dark vertical stripes. Eggs are oval, creamy white. Newly emerged larvae are dull white or light yellow with a brown head, but soon turn green once feeding starts. Fully-grown larvae are slender and 20-25 mm long.
Look for folded leaves, larvae and frass. The similarity of this and another leaf folder, Marasmia patnalis, means that expert examination of specimens is needed to ensure correct identification.
The rice leaf folder attacks tillering and booting stages. High densities can reduce seed production, but this is rare and management is normally not needed. It is a commonly encountered pest, in part because of the obvious damage, but it rarely if ever reaches damaging densities. Most farmer complaints are received from eastern Bhutan.
Eggs are laid singly or in pairs on the leaves and leaf sheaths. Young larvae feed on tender leaves without folding them. Older larvae construct leaf folds. Single larvae may damage multiple leaves. Larvae pupate in loose silken webs in between the leaves or in the leaf sheaths.
The rice leafroller’s egg is close to elliptic, flat shape, about 1 millimetre (5⁄128 in) long, the first birth is milky white, then become yellow-brown, there will be a black spot before hatching.
Larvae have 5 instars generally, the larva body length of mature stage is about 15–18 millimetres (19⁄32–23⁄32 in). They have a brown head, the thorax and abdomen are green at first, then become yellowish-green, and reddish brown when they are mature. There are two spiral-shaped black lines at the posterior margin of the tergum of the front thorax and 8 distinct small black circles at the tergum of the middle and posterior thorax, among which there were six leading edges and two trailing edges.
Pupae are about 9 millimetres (23⁄64 in) long, abdominal 5th to 7th segment near the leading edge with 1 line of dark brown fine, tail tip, with 8 barbed, pupa long with white thin cocoon.
The adult is 7–9 millimetres (9⁄32–23⁄64 in) long approximately, the wingspan is about 13–18 millimetres (1⁄2–23⁄32 in), show flaxen, proala has 3 brown transverse belt, among a relatively coarse short. The central part of the leading edge of the male moth’s proala has a shining and concave eyespot, while the female moth’s proala has no eyespot.
The rice leaf folder attacks tillering and booting stages. High densities can reduce seed production, but this is rare and management is normally not needed.
It is a leaf folding and leaf feeding caterpillar which attacks tillering and booting stages. Caterpillars fold a rice leaf around them and attach the leaf margins together with silk strands. They feed inside the folded leaf creating longitudinal white and transparent streaks on the blade. A heavily infested crop has streaks on the leaves and appears whitish from a distance. Feeding may also make plants prone to fungal and bacterial infection.
The rice leaf folder is the most important species of leaf folder in upland, irrigated and rainfed wetland rice. The use of high-yielding varieties and the increase of insecticides and nitrogenous fertilizers has caused major outbreaks throughout Asia and Oceania, including Fiji. Recently, however, farmers are reducing insecticide use during the first 40 days as they now know that plants can compensate for the early damage.
The rice leaf folder is the most important species of leaf folder in upland, irrigated and rainfed wetland rice. The use of high-yielding varieties and the increase of insecticides and nitrogenous fertilizers has caused major outbreaks throughout Asia and Oceania, including Fiji. Recently, however, farmers are reducing insecticide use during the first 40 days as they now know that plants can compensate for the early damage.
Countries not yet infested by the rice leaf folder should consider all likely pathways for entry, and apply quarantine measures accordingly. It is a major pest of rice, in particular. Many countries throughout Africa, the Americas and also Oceania are at risk. Pathways of introduction are likely to be via produce contaminated by pieces of stem of the hosts infested with larvae or pupae. Many egg, larval and pupal parasitoids (e.g., braconid, bethylid, encyrtid, ichneumonid, trichogrammatid species) and predators (e.g., coccinellids, anthocorids, mirids, pentatomids, reduvids, and spiders) attack the rice leaf folder. The most effective parasitoids and predators vary within the different regions of Asia where the leaf folder occurs.
Before planting: Remove weeds on the bunds as many are hosts of the larvae. Fallow land after rice, or if that is not possible rotate with a different crop. During growth: Do not over apply fertilizer: apply recommended doses at the times suggested. Get advice from government extension officers if this is not known. Weed as required, removing alternative hosts of the rice leaf folder. After harvest: Avoid ratooning the crop as the larvae can carry over to the new tillers as they emerge. Flood the field after harvest or, if not possible, plough the land, turning the stubble into the soil.
Many egg, larval and pupal parasitoids (e.g., braconid, bethylid, encyrtid, ichneumonid, trichogrammatid species) and predators (e.g., coccinellids, anthocorids, mirids, pentatomids, reduvids, and spiders) attack the rice leaf folder. The most effective parasitoids and predators vary within the different regions of Asia where the leaf folder occurs. some other controls may include –
1. Use recommended fertiliser rates.
2. Maintain recommending spacings (22.5 x 20 cm and 30 x 20 cm).
3. Removing grassy weeds from rice fields and surrounding areas may prevent the build-up of rice leaf rollers on alternate hosts.
4. A wide range of natural enemies normally keep this pest in check. Biological control agent are available elsewhere, including in Nepal.
Insecticides are best avoided in the early stages of rice growth, especially as crops can recover from damage caused in the first 40 days. If insecticides are need, i.e., if infestations are high during the booting stage and the flag-leaf is damaged, do the following: Use biorational insecticides, such as neem seed oil (oil from the fruits and seeds of the neem tree, Azadirachta indica); abamectin (a fermentation product from a soil bacterium); or spinosad (isolated from a soil actinomycete). In Fiji, the carbamate, Carbaryl, has been recommended. Other synthetic products, e.g., pyrethroids, such as cypermethrin are likely to be effective, but will destroy parasitoids and predators.
Insecticides may destroy the parasitoids and predators of OTHER insects, e.g., the brown plant hopper, and result in a rapid increase (‘resurgence’) of populations.
তথ্য পাওয়া যায়নি।
তথ্য পাওয়া যায়নি।
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https://pestsofbhutan.nppc.gov.bt/crop-and-pest-identification/insects/rice-leaf-folder/
https://shodhganga.inflibnet.ac.in:8443/jspui/handle/10603/335868
https://link.springer.com/article/10.1007/s42690-023-01026-2
https://academic.oup.com/jee/article-abstract/104/2/653/2199677
https://academic.oup.com/jinsectscience/article/13/1/96/1079392
https://academic.oup.com/jee/article-abstract/107/2/815/922902
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0153918
https://www.sciencedirect.com/science/article/abs/pii/S0022191017300616