Diseases and pests of silkworm in District Pilibhit

CASIRJ Volume 15 Issue 2 [Year - 2024] ISSN 2319 – 9202 Diseases and pests of silkworm in District Pilibhit DR.BARKHA ASSISTANT PROFESSOR OF ZOOLOGY RAM LUBHAI SAHANI GOVERNMENT MAHILA DEGREE COLLEGE,PILIBHIT ABSTRACT Prevention of silkworm diseases is the only way to change sericulture into a sustainable activity PREVENTION IS BETTER THAN CURE by treating silkworms (Bombyx mori L.) that are diseased by pathogenic viruses, fungi, Microsporidians and bacteria. Viral and bacterial diseases are more prevalent causing considerable crop losses; while microsporidian disease is transovarially transmitted and quarantined during the egg production stage. Instances of disease incidence in silkworm crops are generally attributed to persistent pathogens in the rearing environment, inadequate disinfection, unhygienic conditions, secondary contamination etc. Most of the diseases are chronic in nature and the curative measures are not practical. General prophylactic measures such as disinfection and utilization of disease resistant/tolerant silkworm breeds are most effective to harvest good cocoon crops. INTRODUCTION Disease is a condition of abnormality resulting from physical or physiological derangements. It is the result of injury or insult or whatever that goes wrong the insect [1]. Living and non living agents cause diseases in insects and it is the result of interactions between the host and the causal agent. Mulberry silkworm, Bombyx mori is a poikilotherm, susceptible to several diseases. There are no silkworm races at present, which are deemed as totally resistant to diseases or pests. Mulberry silkworm, Bombyx mori is affected by a number of diseases caused by viruses, bacteria, fungi and protozoa. These diseases are known to occur in almost all the silkworm rearing areas of the world causing considerable damage to the silkworm cocoon crop. Microsporidians of the silkworm, caused by highly virulent parasitic Microsporidian or Nosema bombycis, is one of the most serious maladies, which determines the success or failure or sericulture industry in our country. This can be evidenced from the fact that the rise and fall of the microsporiosis diseases corresponds with ups and downs of sericulture industry in silk producing countries of the world . Several strains and species of microsporidia have since been isolated from the infected silkworms, and the diseases is becoming increasingly more and more complex and is also becoming increasing well known in medical arena through the Pathologies they cause in humans with impaired immune system ]. Epizootiology, development of immunodiagnostic kit, fluorescent antibody technique and use of ideal disinfectant, chemotherapy and thermo-therapy techniques and management strategies have been addressed for identification, destruction, prevention and control of disease causing micro-organisms. Techniques of forced eclosion test and delayed mother moth examination have also been stated to play important roles in the detection of the disease. The microsporidia are spore forming, small, obligate, intracellular living eukaryote International Research Journal of Commerce Arts and Science http://www.casirj.com Page 118 CASIRJ Volume 15 Issue 2 [Year - 2024] ISSN 2319 – 9202 infecting both beneficial and non-beneficial insects]. More than 40 general and 1200 species of microsporidia have been recorded from insects and fish . Among these, at least 200 belong to the genus Nosema and most Nosema species are parasitic to invertebrates. A majority of these including N. bombycis and N. tyriae , N. mesnili , N. algerae , N. aphis and N. trichoplusiae , are pathogenic to various insects. More than twenty wild insect species have been found to have microsporidian spores that can cross infect silkworm. Pebrine, i.e. the spores of microsporidian (Nosema bombycis) is one of the most dreaded diseases of the silkworm, it infects almost all ages, stages, breeds and hybrids of the silkworm by both transovarial and peroral infections. It is highly infectious and difficult to eradicate after the occurrence of infection. DIFFERENT SPECIES/RACES OF SILKWORMS IN INDIA There are where is kind of races found in India Silkworm produce in various voltine: Voltinism is a term used in biology to indicate the number of broods or generations of an organism in a year. The term is most often applied to insects, and is particularly in use in sericulture, where silkworm varieties vary in their voltinism. Univoltine (monovoltine) – referring to organisms having one brood or generation per year Bivoltine (divoltine) – referring to organisms having two broods or generations per year Trivoltine – referring to organisms having three broods or generations per year Multivoltine (polyvoltine) – referring to organisms having more than two broods or generations per yea DISEASES AND PESTS FOUND IN SILKWORM ALL OVER INDIA Diseases In India , Silkworm, Bombyx mori L is susceptible to mainly four diseases namely; Grasserie ,Green Grasserie, White Grasserie , Yellow Grasserie , Microsporidians Flacherie, Muscardine and Pebrine. The average silkworm crop loss in India due to diseases is to the tune of 15–47%, while it is 10–15% in other countries like Japan, China and Italy. Out of four diseases, Flacherie (33.88%) is the major killer in India. The incidence of silkworm diseases is more during autumn season (35–47%) than spring (15–20%) in North West India. Generally, bivoltine silkworms are more susceptible to diseases as compared to multivoltine silkworm breed. The important factors responsible for the high disease incidence during autumn season are higher pathogen load, wider fluctuation of temperature between day and night, higher humidity in the late stage of rearing and poor quality of mulberry leaves available for rearing in North West Indian condition. The most popular methods of disease control in silkworm cocoon crop are prophylactic by controlling pathogens in rearing rooms and preventing pathogen entry during rearing. There is no race of B. mori, totally resistant or immune to diseases and pests. Hence, proper disinfection is required to kill all the pathogens present in the rearing environment and to eliminate risk of disease transmission. Proper, effective and strict disinfection of rearing house, its surroundings, appliances and hygienic measures are most crucial as policy of “Prevention is better than cure” is best in silkworm rearing. International Research Journal of Commerce Arts and Science http://www.casirj.com Page 119 CASIRJ Volume 15 Issue 2 [Year - 2024] ISSN 2319 – 9202 Pests Any (insect or non-insect) organism, which interferes with human welfare,Leading to economic loss is termed a pest.• Two important pests are found to cause economic loss of silkworm crop.• The silkworm in larval stage is attacked by a tachinid fly (Exorista bombycis),Commonly known as uzi fly, leading to considerable decline in cocoon yield. • In cocoon stage (seed / stifled /moth pierced cocoons), the silkworms are Attacked by dermestid beetles (Dermestes spp.) These beetles are commonly Referred to as carpet beetles. They are reported to cause considerable . Reduction in egg production in silkworm egg production centers (grainages). Diseases Causative agent General Some distinct characteristics symptoms Nuclear polyhedrosis Bombyx Mori nuclear polyhedrosis virus Swelling on intersegmental region shining and fragile skin milky white fluid Cadavers greyish black and flacchid Turbid and Not distinct white occlusion bodies are present Cytoplasmic polyhedrosis Bombyx Mori cytoplasmic polyhedrosis virus Clear no occlusion bodies present Posterior midgut ivory in colours , shrunken and striated occlusion bodies are present Infectious flacheri Bombyx Mori Infections flacheri virus Translucent cephalothoraxic reason diarrhea retarded growth milky white midgut white is faces larva pale thin and small growth slow and asynchronous faeces remain attached to the anus Larvae vomit head raised growth and moulting asynchronous larvae discolored flaccid faeces watery cadavers have a flattened Clear without occlusion bodies Contains yellow brown fluid pink viral spherical bodies present stains with International Research Journal of Commerce Arts and Science http://www.casirj.com Shiny just before moulting fragile excuding, fluids in late in starts spiracles black and cuticle with black spots Not distinct Not distinct Page 120 CASIRJ Volume 15 Issue 2 [Year - 2024] shape Densonucleosis Bombyx Mori densonucleosis virus Thorax mostly translucent like flacheri or bacterial flacheri anorexia late moulting bodies shrunk integument not fragile ISSN 2319 – 9202 pyroxin methyl green Clear without occlusion bodies Contains yellowish green fluid coccai and diplococcai very abundant but no occlusion bodies Not distinct DISEASES AND PESTS OF SILKWORM FOUND IN UTTAR PRADESH: Diseases in Uttar Pradesh of silkworm are found mainly four diseases namely; Grasserie, Flacherie, Muscardine and Pebrine. In UP mostly Mulberry silkworm are found and used for various silk production and different uses of thread and silk fibers .The important factors responsible for the high disease incidence during autumn season are higher pathogen load, wider fluctuation of temperature between day and night, higher humidity in the late stage of rearing and poor quality of mulberry leaves available for rearing in North West Indian conditions. Microsporidians Pathogenicity Spore form Spore size in mm. isolate Length Breadth N.bombycis High Oval 3.8 2.6 Nosema.sp.M11 Low Oval 3.9 1.9 Nosema.sp.M12 Low Ovo4.5 2.0 cylindrical Nosema.sp.Lbms Low Ovo4.36 2.14 cylindrical Pleistophora High Oval 2.7 1.6 NIK-2r Low Oval 3.6 2.8 NIK-4m Low Oval 5.0 2.1 NIK-5hm High Ovo5.0 3.1 cylindrical NIK-5d High Oval 3.70 2.70 Pests Any (insect or non-insect) organism, which interferes with human welfare,Leading to economic loss is termed a pest.• Two important pests are found to cause economic loss of silkworm crop.• The silkworm in larval stage is attacked by a tachinid fly,Commonly known as uzi fly ,bettel,lizard , leading to considerable decline in cocoon yield. • DIFFERENT RACES ORVOLATINES FOUND IN DISTRICT PILIBHIT : International Research Journal of Commerce Arts and Science http://www.casirj.com Page 121 CASIRJ Volume 15 Issue 2 [Year - 2024] ISSN 2319 – 9202 In Pilibhit , attempts to rear bivoltine hybrids resulted only a sporadic success and that too confined only to some seasons of the year, when climatic conditions are not hostile to silkworms The bivoltine breeds developed earlier were with an objective to have higher pupation rate and all the other characters balanced at a moderate level for enabling easy rearing by the farmers. Therefore, limited hybrid vigour could be realized when two such breeds are crossed because both the breeds are on par in almost all the characters. In Pilibhit, only the bivoltine species are found majorly Bivoltine: Suitable for warmer places. Larval duration shorter compared to univoltines. Larva is robust, cocoon and silk quality is good. Moderately suitable to high temperature and high humidity. And the Races found in Pilibhit are: 1. NV4D2 × SH6 2. SH6 × NV4D2 3. CSR2 × CSR4 4. CSR4×CSR2. In your locality , the major disease found on training program of sericulture for silk production was mainly the diseases found on mulberry silk and their silk worms and pests as well was insects and fly around . The diseases we found during our sericulture training program is as given below: Diseases of mulberry silkworm in races CSR2 × CSR4 IN DISTRICT PILIBHIT VIRAL DISEASES Viral diseases of silkworms pose a major problem to sericulture as they account for almost 70% of the total loss due to diseases. In managing viral diseases, it is difficult to identify the pathogens causing the diseases and symptoms at the early stages of the disease. Viral diseases of silkworm comprise of inclusion and non-inclusion types. The inclusion of virus disease form typical inclusion bodies. They are nuclear polyhedrosis and cytoplasmic polyhedrosis, which can be more easily identified through an ordinary microscope. 1. GRASSERIE: Causative agent: Bombyx mori Nuclear Polyhedrosis Virus Occurrence: The disease prevails all through the year but its severity is more during Summer and Rainy seasons. International Research Journal of Commerce Arts and Science http://www.casirj.com Page 122 CASIRJ Volume 15 Issue 2 [Year - 2024] ISSN 2319 – 9202 Source of infection: Silkworm gets infected when it feed on contaminated mulberry leaves. The milky white fluid released by the grasserie larvae, contaminated silkworm rearing house and appliances are the sources of infection. Predisposing factors: High temperature, low humidity and poor quality mulberry leaves. Symptoms:  The skin of infected larvae becomes shining before moult and fails to moult.  Inter segmental swelling appears and the colour of the body becomes yellowish.  The infected larvae move restlessly in the rearing bed/ along the rim of the trays.  Infected larval body ruptures easily and turbid white haemolymph oozes out. Management:  Practice thorough disinfection of rearing house, its surroundings and appliances with any recommended disinfectant.  Conduct an optional disinfection with 0.3% slaked lime solution when high incidence of disease noticed in the previous crop.  Practice personal and rearing hygiene.  Collect the diseased larvae and ensure its proper disposal.  Maintain optimum temperature and humidity in the rearing house.  Feed quality mulberry leaf and avoid overcrowding.  Apply recommended bed disinfectant as per schedule and quantity.  Feed Amruth as per schedule to control grasserie disease. BACTERIAL DISEASE Bacterial diseases are common in silkworms and tend to occur in the hot, humid summer and autumn rearing seasons. Generally, the silkworms are infected by bacterial disease if disinfection is neglected, faeces accumulation in the rearing tray, improper handling of mulberry leaves (Sivaprasad et al., 2003). The silkworm diseases are classified as bacterial Septicaemia, bacterial toxicosis or gastro-enteric diseases. The infected silkworm becomes motionless and lethargic. Body of the infected silkworm become soft, infected larvae stop feeding, become weak and retarded growth, fail to settle for moult and start vomiting releasing contaminated body fluid, larvae on death putrefy on the rearing bed and starts emitting foul smell. 2.FLACHERIE: Causative agent: Bombyx mori Infectious flacherie virus/Bombyx mori Densonucleosis virus or different pathogenic bacteria viz., Streptococcus sp./Staphylococcus International Research Journal of Commerce Arts and Science http://www.casirj.com Page 123 CASIRJ Volume 15 Issue 2 [Year - 2024] ISSN 2319 – 9202 sp./Bacillusthuringiensis/Serratia marscesence individually or in combination of bacteria and viruses. Occurrence: The disease is common during Summer and Rainy seasons. Source Infection: Silkworm gets infected by eating contaminated mulberry leaf. Dead diseased silkworm, its faecal matter, gut juice, body fluid are the sources of pathogen contamination. The infection can also takes place through injuries/cuts/wounds. Predisposing factors:Fluctuation in temperature, high humidity and poor quality of leaves. Symptoms:  The larvae become soft and flaccid.  The growth of infected larvae retarded, becomes inactive and vomit gut juice. The faeces become soft with high moisture content. Sometimes chain type excreta and rectal protrusion also observed.  Larval head and thorax become translucent.  When infected with Bacillus thuringiensis symptoms of toxicity such as paralysis and sudden death are observed. After death, larvae turn black in color and gives foul smell.  Some times, the dead larvae turn red when infected with Serratia sp. Management:  Disinfect the rearing house, its surroundings and equipments with recommended disinfectant mentioned above.  Pick up diseased larvae and dispose them by burning.  Provide good quality leaf grown under good Sunlight and recommended inputs. Do not provide over matured/over stored /dirty leaf to the silkworms  Avoid starvation, overcrowding and accumulation of faeces in the rearing bed.  Rear silkworms under optimum temperature and humidity.  Avoid injury to the larvae.  Apply recommended bed disinfectant as per schedule and quantity.  Feed Amruth as per schedule to control flacherie disease International Research Journal of Commerce Arts and Science http://www.casirj.com Page 124 CASIRJ Volume 15 Issue 2 [Year - 2024] ISSN 2319 – 9202 FUNGAL DISEASE : Generally, fungal disease is common mostly during the rainy season but the incidence is very high during winter. It is the most common dreadful disease caused by Beauveria bassiana. Recently, we identified different fungal pathogens from the infected silkworms and sequenced the fungal colony. B. bassiana spores spread among silkworm populations via the air, soil, mulberry leaves, tools used for rearing, and dead individuals. After adhering to the silkworm integument, the spores begin to germinate, before secreting enzymes to break and penetrate the cuticle to allow replication in the haemolymph, finally resulting in the death of the infected silkworm. Diseased larvae lose their appetite and become Inactive. The colour of larvae turns pale gradually ceases movement within 12–18 h of infection. During later stages, the body becomes harder, brittle, and mummifies covered with white encrustation or white coating looking like a white chalk pencil 3.MUSCARDINE: Causative agent : Among fungal diseases, White Muscardine is common. The disease is caused by Beauveria bassiana. Occurrence: The disease is common during Rainy and winter seasons. Source of Infection: The infection starts when conidia come in contact with silkworm body. Mummified silkworms / alternate hosts (most are lepidopteron pests), contaminated rearing house and appliances are sources of infection. Predisposing factors : Low temperature with high humidity. Symptoms:  The larvae loose appetite and become inactive.    Presence of moist specks on the skin. The larva vomits and turns flaccid. After death, larva gradually becomes hard followed by mummification due to growth of aerial mycelia and conidia over the body and body turns chalky white. International Research Journal of Commerce Arts and Science http://www.casirj.com Page 125 CASIRJ Volume 15 Issue 2 [Year - 2024] ISSN 2319 – 9202 Management:  Disinfect the rearing house, its surroundings and equipments with recommended disinfectant as mentioned above.  Control mulberry pests in the mulberry garden.  Pick up diseased larvae before mummification and dispose them by burning  Avoid Low temperature and high humidity in the rearing house. If required use heater/stove to raise the temperature.  Regulate bed humidity during rainy season by dusting slaked lime powder during moult.  Apply bed disinfectant, Vijetha and Vijetha supplement/Ankush/any recommended bed disinfectant as per schedule and quantity. MICROSPORIDIAN DISEASE Microsporidia comprise one of the largest groups of obligate intracellular pathogens and can infect virtually all animals, but host response to these fungal-related microbes has been poorly understood. Pebrine is the most important disease of silkworm that is caused by the protozoa called Nosema bombycis. Pebrine has commonly observed in all the seasons but during the rainy and winter season, the infection level is more. It is transmitted to offspring by transovarial. This is one of the important studies, presently not only Nosema bombycis and other microsporidia are causing devastating pebrine disease to the silkworms. All the microsporidian having unique characters such as shape, size, movement, etc., but they show different transmissions. 4 .PEBRINE: Causative agent: Nosema bombycis / different strains of microsporidia. Occurrence: Non-seasonal Sources of Infection: Silkworm gets infected through eggs (Transovarian/Transovum transmission) or by eating contaminated mulberry leaf. Infected silkworms, faecal matter, contaminated rearing house and appliances and alternate hosts (mulberry pest) are the sources of infection. Symptoms Irregular hatching of silkworm eggs.Irregular size of the larval body and moulting.The infected larva looses its appetite and becomes inactive with wrinkled skin.Black pepper-like spots appear on the body of the infected worms.White postules appear on the silkgland when examined under microscope with presence of shining oval spores. International Research Journal of Commerce Arts and Science http://www.casirj.com Page 126 CASIRJ Volume 15 Issue 2 [Year - 2024] ISSN 2319 – 9202 Management:  Disinfect the rearing house, surroundings and with recommended disinfectant as mentioned above.  Conduct strict mother moth examination and surface disinfection of silkworm eggs to produce and rear disease free layings.  Follow strict hygiene maintenance during rearing.  Control mulberry pests in and around the mulberry garden.  Apply recommended bed disinfectant, Vijetha/Ankush as per schedule and quantity.  Monitor seed crops constantly to eliminate the microspodian infection. PESTS OF MULBERRY SILKWORM : 1.Uzi fly (Exorista bombycis) Symptoms of attack and extent of damage The Uzi fly lays one or two cream colored eggs (measuring the size of a Pin head) on the silkworm larva. Generally, it prefers grown up larva (i.e.,4th or 5th instars) for egg laying The eggs hatch in 48 to 62 hours. A black scar is formed at the point Where the egg hatches and the uzi larva (maggot) enters the body of the Silkworm using the hooks (pro-thoracic hook) attached to the mouth. From This black scar, the pest attack can be identified. Factors responsible for outbreak of Uzi fly  -Large scale and overlapping rearing of host (silkworm).  -Favourable climatic conditions (temperature range of 20 – 30°C and Relative humidity of 60 – 90%) facilitates continuous host / silkworm.  -Rearing which in turn helps the host availability. - Increased adult (uzi fly) longevity.  -Higher egg production and egg hatchability. - Reduced activity of the natural enemies like parasitoids,  Management  A minimum gap of 20 days should be maintained between the two silkworm Rearings.  The cracks and crevices on the rearing house floor must be kept closed. International Research Journal of Commerce Arts and Science http://www.casirj.com Page 127 CASIRJ  Volume 15 Issue 2 [Year - 2024] ISSN 2319 – 9202 Collection and destruction of uzi infested silkworm larvae. 2. Dermestes Beetle: (Dermestes spp. ) Symptoms of pest attack and extent of damage  -The grubs cause more damage than adults. o The infested cocoons (especially seed and stifled cocoons) show the  -Presence of multiple irregular holes on them. o Though they show preference for feeding on the left over/dead matter in  -The cocoons, they do attack the green cocoons as well as the egg laying  -Moths whenever their population gets increased  The estimated damage level due to the beetle attack to the pupae is 16.62 And moth 3.57% with 20.19% reduction in egg production in grainages,Especially those coming under government sector.  Factors responsible for pest outbreak  Storage of large quantities of moth pierced as well as stifled cocoons over A long period of time (more than 6 months). Management  Storage of rejected cocoons and perished eggs in the grainages for long  -Period should be avoided.  -The cocoon storage rooms should be cleaned periodically.  -Before and after emergence of silk moth, the grainage premises should be Kept clean and tidy.  -Provid wire mesh to doors and windows in Pierced Cocoon (PC) storage Rooms to avoid free movement of the beetles and grubs from PC storage Room to grainage operation rooms. International Research Journal of Commerce Arts and Science http://www.casirj.com Page 128 CASIRJ Volume 15 Issue 2 [Year - 2024] ISSN 2319 – 9202 Mites : Pediculoides ventricosus damage the larvae . The toxic substance produce by the mite kills the silkworm. In addition, ants ,lizards ,birds , rats and squirrel also cause considerable damage to silkworm larvae as well as the cocoons. CONCLUSION: Any disease incidence noticed during late instars of silkworm affect the pupal formation and moth emergence leading to reduced egg production. As a result, diagnosis of silkworm diseases is most important as part of successful silkworm cocoon production.The most basic and necessary work for industrial utilization of insect resources such as silkworm is an insurance of resources through import and collection of various gene resources. Even in Japan, where the development of utilization technology of insect function is activated, new science such as “insect function utilization science” is born. Silkworm occupies 65% of animal gene resources that conserved by Ministry of Agriculture and Forestry. And there are about 1000 strains which are conserved in Japan Bioresources Research Center, National Genetics Research Center, and each University(Lee, 1998). In addition, through continuous research of these resources, the results such as creation and utilization of mutant races and others, play an important roles in the International Research Journal of Commerce Arts and Science http://www.casirj.com Page 129