Pests, Pandemics, Preparedness and Biosecurity

Transboundary pests are a serious threat to food security and environment, a condition exacerbated in recent decades by the globalised movement of people and commodities. India witnessed an upsurge of desert locust in 2020 with their swarms attaining epidemic proportions during COVID-19 pandemic. Rajasthan was on high alert with swarms entering Madhya Pradesh, Uttar Pradesh, Punjab, Haryana Gujarat and Telangana between May and June. As in the first week of July 2020, FAO had sounded a high alert with the possibility of more swarms of locusts likely to migrate from Somalia to along India-Pakistan border (FAO, 2020a, b). Cassava mealybug (CMB) is the latest invasive insect in 2020 first observed in Thrissur, Kerala (Joshi et al., 2020) and has spread to Tamil Nadu causing 9–46% infestation. Prevention of spread to unaffected areas and action for eradication (ICAR-NBAIR, 2020) and importation of CMB-specific parasitoid, Anagyrus lopezi is currently underway. The fall armyworm (FAW) invaded maize in India during May 2018, and spread across all maize growing states. Recently it was also reported from Bangladesh. India recommended eight insecticides however, with conservation and augmentative biocontrol-cum cultural control interventions given prime importance (AFFRC, 2019). Rugose spiralling whitefly (RSW), first noticed on coconut from Tamil Nadu and Kerala in 2016, later spread to Andhra Pradesh, Karnataka, Goa and Assam, through infested seedlings and transportation of plant materials (CPCRI, 2019). Banana, mango, sapota, guava, cashew, maize, ramphal (local fruit in India), oil palm, Indian almond, water apple, jack fruit and many ornamental plants are host crops of RSW (NBAIR, 2020). Natural buildup of the parasitoid, Encarsia in RSW endemic areas and enhancing its niche survival are given focus at present. South American Tomato Moth (SATM), an invasive insect on tomato both under greenhouse and field conditions, was reported in 2014 (Sridhar et al., 2014) with its spread to several states, has established as a regular pest. While natural incidence of Metarhizium anisopliae on larval SATM was up to 35%, resistance breeding through screening of wild and cultivated tomato genotypes is underway as a long-term management strategy. Papaya mealybug (PMB) caused significant damage to agricultural and horticultural crops since its documentation in 2007 at Coimbatore, Tamil Nadu. Mulberry crop over 1500 ha in Tamil Nadu too got destroyed (Shekhar et al., 2011). However, classical biological control using Acerophagus papayae from Puerto Rico is a success story that reduced incidence of PMB from 49 to 3%. Cotton mealybug (CMB) first recorded in Gujarat in 2005 caused yield loss of 30–40% in Punjab amounting to INR 1590 million during 2007 (Dhawan et al., 2007) and 40–50% in Gujarat. Infestation of CMB was reported from 71, 141, 124 and 194 species of plants belonging to 27, 45, 43 and 50 families, respectively, across cotton growing zones in India (Vennila et al., 2011) and the parasitoid, Aenasius bambawalei offered fortuitous biological control (Gautam et al., 2009). Invasive eucalyptus gall wasp (EGW) of 2001 (Anonymous, 2007), spread across south (Jacob et al., 2007), central (Kumar et al., 2007) and northern states threatening the productivity of paper and pulp industry in 2007, however, is being kept under check presently by the native parasitoids (Ramanagouda et al., 2011). Other established invasive plant pests in India include silver leaf whitefly (Ananthakrishnan, 2009), coconut eriophyid mite (Sathiamma et al., 1998), spiralling whitefly (Mani, 2010) and coffee berry borer (Singh & Ballal, 1991) that are managed on need basis. Occurrence of Fusarium wilt (race 1) infecting Cavendish in 2010 (Thangavelu et al., 2011) and tropical race 4 (TR4) reported from Uttar Pradesh in 2017 was also recorded from Bihar, Madhya Pradesh, Gujarat and Maharashtra. Productivity of banana, especially Cavendish varieties is highly reduced by TR4 in several parts of the country (FAO, 2019) and the poor man’s source of nutrition was at stake. Infected areas in Bihar and Uttar Pradesh saw a remarkable control of TR4 on account of microbial consortium developed by the Indian Council of Agricultural Research (ICAR). Citrus greening disease is destructive in major citrus belts of Maharashtra, Punjab, Southern and North-East India with its transmission through grafts and psyllid vector (Das, 2008) necessitating supply of disease-free citrus seedlings to reduce its incidence and damage.

Nematode problem is gaining momentum across all cropping systems of Indian agriculture. Plant-parasitic nematodes cause 21.3% crop losses across 19 horticultural and 11 field crops (Kumar et al., 2020). Root knot, reniform, lesion, foliar, burrowing and bulb-cum-stem nematodes are the most destructive and difficult to control pests that certifications have become essential nowadays for protected cultivation in glass and polyhouses. Both ecto- and endo-parasitic nematodes inflicting serious damage are a cause of concern in forests. A potential risk of introduction of pine wilt nematode in the Himalayan region of Indian territory exists through the import of coniferous wood and their products especially from China through Nepal, Bhutan and Myanmar (Khan, 2020). Declining organic matter and pH directed micro-irrigation and fertigation have accentuated the problem both in the open and protected conditions. Weeds also cause reduction in yields of various crops and are more harmful than insects and diseases with potential crop yield losses ranging between 15 and 76% (Gharde et al., 2018). Herbicide resistance in weeds, changing climate, direct-seeded rice and zero cultivation led weed species, plant parasitic Orobanche in mustard and alien weeds viz., Parthenium, Lantana, Ageratum, Chromolaena and Mikania (Rao, 2018) have become aggressive despite wider use of chemical and bio herbicides for weed control (Kaur et al., 2014).

Vast agro climatic, geographical regions and cultural differences have led to differential husbandry practices as well as diseases occurrence in livestock. In recent years, emerging and re-emerging diseases of livestock, poultry and piggery have tremendously increased along with growing demand for and supply of meat, milk, eggs and fish. Fresh and processed products are witnessing increased trade and likelihood of carriers of contaminants. Breach of biosecurity in intensified livestock production and management systems is often the reason for spread of zoonotic and other animal diseases with considerable impact on public health. The societal conundrum that exists in the country prohibits the drastic measure of slaughtering and disposal of the infested and in-contact animals and hence the rate and speed of disease spread are faster even if identified on time; besides wet markets, across the country, are very conducive for zoonotic diseases. Foot and mouth disease (FMD) is a continuing epidemic decreasing the productivity of cattle, meat, wool, etc., due to unrestricted movement of animals across Indian states and incomplete vaccination. In FMD control areas, there is built-up of herd immunity and substantial fall (Subramaniam et al., 2013). Outbreak of Peste-des-petits ruminants (PPR) affecting goats and sheep in Tripura is a transboundary disease (Begum et al., 2016) and about 99% nucleotide identities existed with Bangladeshi viral strains (Muthuchelvan et al., 2014). Several PPR outbreaks were encountered in India with high morbidity (50–90%) and mortality (50–85%; Muthuchelvan et al., 2015). Bluetongue transmitted by Culicoides spp. was severe in Karnataka, Andhra Pradesh and Tamil Nadu (Hemadri & Hiremath, 2011) and impacted the farmers in the recent past.

Lumpy skin disease (Anonymous, 2020a), a capripox infectious viral disease, transmitted by mosquitoes and flies is fast spreading among cattle and bovines in districts of Maharashtra and Assam. Sheep poxvirus and goat poxvirus cause economic losses to small ruminant husbandry with mortality of young animals exceeding 50% in almost all states (Bhanuprakash et al., 2011). Bovine herpesvirus-1, higher in crossbred and exotic breeds, causes economic losses through reduction in milk yield and impact on national and international trade of germplasm and livestock. Bovine viral diarrhoea in cattle (Sood et al., 2007), sheep and goats (Mishra et al., 2009) and buffaloes (Mishra et al., 2008) are also important. Picobirnaviruses are emerging threat to mammalian and avian species associated with enteric and respiratory infections. Bacterial diseases viz., haemorrhagic septicemia, black quarter, anthrax, brucellosis, leptospirosis, listeriosis, tuberculosis, bovine tuberculosis and para tuberculosis are infectious on livestock with some of them having zoonotic significance. Anthrax is one of the top five zoonotic diseases in India. Listeriosis is also fatal to ruminants (sheep, goat, cattle, buffalo and camel), non-ruminants (horse, pig, canine, rodent, wild animals and birds) and humans (Dhama et al., 2013, 2015).

Bovine tuberculosis is a chronic bacterial zoonotic disease, which easily spreads to humans through inhalation of aerosols or ingestion of unpasteurised infected milk (Prasad et al., 2005). Parasitic diseases viz., fascioliasis in sheep, trypanosomiasis in wild animals, dogs, horses, camels, donkeys, cattle and buffaloes, bovine tropical theileriosis in indigenous cattle and crossbreeds and babesiosis in bovines are regular pests of ruminants (Saminathan et al., 2016). Recent incidence of tick-borne disease causing Congo-haemorrhagic fever associated with sheep has made inroads into Rajasthan and is an emerging zoonotic disease (Tripathi et al., 2020). The slaughterhouse wastes thrown outside become agents for further spread of vector-borne diseases of animals closely associated with wet market. Although rinderpest of cattle in the past has been eradicated, the same cannot be said of FMD and anthrax diseases.

In pigs, incidence of brucellosis, swine erysipelas, greasy pig disease, Streptococcus suis infection and methicillin resistant Staphylococcus aureus infections are common and widespread. Injudicious use of antimicrobials in pig rearing has resulted in emergence of multiple drug-resistant bacteria with significant public health implications. Antimicrobial resistant bacteria are transmitted to humans through direct contact and through the environment, pork and pork products (Rajkhowa et al., 2018). Viral diseases among pigs are classical swine fever, rotavirus infection, FMD and porcine reproductive and respiratory syndrome. India reported first case of African swine fever and its outbreaks in Assam and Arunachal Pradesh both in domestic pigs and wild boar during 2020. Porcine circovirus-2 infection is an emerging disease and its tracking of the epidemiological pattern in northeast hilly regions of India (28% of pig population) gives an alarm for alertness (Rajesh et al., 2020). Diseases of poultry that have produced historical panzootic along with zoonosis are avian influenza and Newcastle (Ranikhet) disease. Furthermore, viral diseases viz., fowl pox and avian leukosis, the bacterial diseases like tuberculosis, fowl cholera and Escherichia coli infections cause outbreaks in poultry farms. Other fatal infections are due to tick fever, infectious coryza, protozoans causing coccidiosis, internal (round and tape worms) and external (lice, ticks, mites and fleas) parasites are debilitating pestilence to birds and workers (Singh, 2020). Avian malaria can be threatening to the poultry and needs to be kept under vigil. Farm families are often exposed to the bovine encephalitis, swine flu and many other diseases of piggery in addition to virus influenza of poultry. Avian influenza had hit 12 Indian states alongside of COVID-19 pandemic during 2021 and the chicken consumption got reduced by 20%.

Primary constraint to sustainable aquaculture is the occurrence of diseases affecting product trade and socioeconomic status of fishers. Growth of shrimp aquaculture in India during last two decades has significantly increased the diseases (Pantoja et al., 2008). The loss due to disease outbreaks in shrimp farms located in nine coastal districts was estimated to be INR 10,000 million (Binesh & Jithendran, 2013). Disease occurrence is variable in ponds, open-water and cage culture. Mostly, the protozoan ciliates, monogenetic trematodes and crustacean ecto parasites are reported. The Ichthyophthirius, causes white spot or ich in freshwater fishes. Bacterial diseases of septicemia, edwardsiellosis, flexibacteriosis, bacterial gill disease, mycobacteriosis and columnaris are often reported in semi-intensive or intensive pond culture systems (Das, 1999; Fegan et al., 1991). Saprolegniasis and epizootic ulcerative syndrome are important fungal diseases in fish culture (Durai et al., 2015). Many viral infections viz., white tail/white muscle, monodon baculovirus, yellow head disease, white spot disease, Taura syndrome virus, infectious hypodermal and hematopoietic necrosis virus, hepatopancreatic parvovirus, infectious myonecrosis virus, acute hepatopancreatic necrosis/early mortality syndrome and hepatopancreatic microsporidiosis are of concern to Indian aquaculture (Mishra et al., 2017). Cyprinid herpesvirus-2, koi ranavirus, carp oedema virus, megalocytivirus and goldfish hematopoietic necrosis herpes virus are the diseases of ornamental fish culture (Glazebrook et al., 1990). Outbreaks of Tilapia lake virus was reported in West Bengal and Kerala (Behera et al., 2018). Intensive shrimp farming with imported Penaeus vannamei (Rajendran et al., 2016) brought in microsporidians, which is causing huge loss to Indian shrimp industry.

In India, with its higher population density and poverty, the requirement of food and nutrition is of paramount importance for development of children and adults including women. Number of persons in the age group of 50 and above would increase significantly in coming years with each one requiring different but calibrated amounts regarding energy and protein. Indian farming is becoming more complex due to competing factors of growing population, land competition, climate change, food, feed and nutritional expectations, labour availability, mechanisation, producer and consumer dilemmas, price policies, scarce capital, environmental consciousness in addition to societal pressure on basic health and safety expectations. All these factors would offset the balance of country’s economy vis-à-vis nutritional or energy requirements to be achieved in a sustainable way. Any reduction in supply of pulses and edible oils would adversely impact the nutritional food intake of population, especially economically weaker section of the society. Horticultural crops serve as the best alternatives to food crops economically and ecologically in providing nutritional security. Both fruits and vegetables are primary sources of minerals and proteins in addition to other compounds such as antioxidants. The requirement of vitamin A, C, B1, B12 and many others are absolutely met by the Indian mass to a larger extent through horticultural crops, which are highly susceptible to pests. Although, horticultural production seems to have increased whether it would keep pace with the increasing demands of rising population and the middle-class segment is a matter of concern. Social changes associated with rural youth shifting to urban areas for education and work vis-à-vis changing pattern of food preference have transformed the balance between demand and supply of type and quantity of food items not to mention of the variety of processed and semi-processed products in use.

Demand-driven growth in livestock production in rural and semi urban areas will enable millions of poor to escape the poverty trap besides contributing towards women empowerment. Share of poultry and other meat that serve as source of protein, vitamins and minerals is expected to grow from 12 to 24% by 2030 on account of rapidly changing consumer behaviour. The poultry industry in India is constantly advancing due to the use of modern technology and switching from live bird to fresh chilled and frozen poultry product market. Poultry sector is to produce designer eggs. These are organic eggs rich in omega 3 fatty acids and with lower levels of saturated fats and cholesterol. Poultry industry with its growth rate of 12–15% is providing a low cost source of dietary protein to the consumers as well as employment opportunities. Weak hygiene and inadequate biosecurity in rural settings of poultry are often compensated arbitrarily by intensive use of antibiotics. Unsafe disposal of poultry litter leads to multi-drug resistance properties in bacteria. Antimicrobial resistance is thus the greatest threat in our fight against infectious diseases. Antibiotics such as tetracycline, doxycycline and ciprofloxacin, critical to human health, are used for growth promotion in poultry. A more concerning issue is the use of colistin for growth promotion, prophylaxis and therapeutic purposes in poultry that move in food chain. Rampant use of benzathine penicillin for animal use is obvious through six manufacturers as against just one for human use. Misuse of antibiotics and presence of Salmonella and cholesterol in poultry meat are the cases of unsafe food of human consumption. With increasing consumption of seafood globally, aquaculture has grown dramatically over the years and as per an estimated report the infectious microbial diseases of fish cause loss of around US$ 6 billion each year. Changing forest expose the domestic livestock to a new range of pathogens and vectors that previously existed only in wildlife niches. While pandemics are once a while, everyday living circumstances of humans happen in an environment which is highly infectious prone. Closer or overlapping contact between wildlife, animals and humans and organised livestock and poultry farming in close association with people cause spread of infectious diseases with potential to threaten health, economies and food security while compromising biosecurity. Increased trade of raw commodities and processed foods carry the pathogens that act as food poisons affecting health of humans in addition to introducing new organism into countries and continents (Yadav et al., 2020). Whether it is food or nutritional security or human health they are all fundamentally interconnected and lack of nutritional food and its safety make the population susceptible to several diseases. Many of the pests and pandemics not only impact farmers directly at farm level but also through disruption of supply chain and position of agriculture at national level impacting food and nutrition of a wider population. Workers engaged in cattle, pig or poultry farming when impacted by zoonotic diseases migrate to their home districts or states that result in reduction of labour availability to farmers as it happened with the pandemic of COVID-19. Mass movement or displacement of labour has not only left the employment in agricultural and non-agricultural sectors vacant but the movement itself served as a cause for secondary spread of pandemic.

Most of the problems in agriculture from soil health, pestilence, zoonotic, pandemics and food safety can be traced to adverse impact of intensive, mono-cropping, seriously threatening natural as well as agro biodiversity in soil, forests and aquatic systems. Pest infestation at a pandemic level reflects an invasive or loss of biodiversity. Population growth to 1.6 billion by 2050 seeks higher provisioning for energy and commodities aggravated by changing dietary habits and climate change. Demographic pressure would compel modification of natural landscapes and intensification of agriculture and allied sectors leading to biodiversity loss per se. Biodiversity loss leads to increased pests and pandemics and vice versa. Epicentres shall sprout as humans, livestock and wildlife share large pools of microorganisms in proximity. Further, manifestations of new species or adaptation of existing species to new hosts would result in changing structure and rate of emerging infectious diseases. Loss of species can increase encounter rates between pathogens and hosts when the lost species are not hosts for the pathogen. Expansion of agricultural areas through deforestation can lead to increased wildlife-human and livestock-wildlife contact with livestock-human transmission leading to a range of infectious disease outbreaks and emergency events and modification of transmission mechanism. Besides agricultural encroachment, road construction, logging, dam building, irrigation, wetland modification, mining, the concentration or expansion of urban environments, coastal zone degradation and modification of natural landscapes cause a cascade of factors that exacerbate infectious disease emergence. Use of drugs such as antibiotics, vaccines and agrochemicals destroy the biodiversity and openly impact the ecosystem services with the expected management practices of pests during pandemics. Indiscriminate policies and practices over the last 60–70 years with scant respect for environment and biodiversity have caused India maximum harm. The nation must resolve to leave the current forests and natural landscapes to safeguard biodiversity and to avoid frequent and virulent pest outbreaks. One of the factors leading to emergence of epicentres of zoonotic is the wet meat market especially when wild animals are slaughtered as in the case of COVID-19. Serious thinking on this is needed to prevent future zoonotic and epidemics so as not to repeat the events of Spanish flu of 1920 and COVID-19.

Most of the zoonotic viruses have significant possibilities in bioterrorism and have potential to wipe out humans and animals although neither any evidence exists as on date nor any sane person on earth would attempt to exploit microbes that are less evolved than mankind. Advances in molecular biology such as gene editing can make profound changes in genetic manipulations of organisms, and implications of such technologies in occurrence of pandemic and its mitigation need serious thinking. Institution of appropriate and timely biosecurity measures is an important instrument for protection and improvement of animal health. Breach in biosecurity due to ignorance and lapses in adoption of timely biosecurity measures in management of livestock, poultry and fish are salient reasons for the high incidence of emerging and transboundary infectious diseases. India’s stance, like most of the nations across the globe, to the ongoing COVID-19 biosecurity crisis is largely responsive and reactive than being proactive from a biosecurity perspective, exposing low level preparedness towards pandemics (Athavale, 2020). In India, biosecurity has remained next to biosafety even after four decades of legislation. The proposed Agricultural Biosecurity Bill and the National Biotechnology Regulatory Authority aim to establish an integrated national biosecurity system covering plant, animal and marine issues. Under the Integrated disease surveillance programme, a network of public laboratories with biosafety practices and infrastructure was established although up-gradations are needed to be continuous considering technological advancements. In India, about 30 bio-safety level (BSL) laboratories of the level of BSL-III or BSL-II+ are currently under operation with only two BSL-IV facilities. Prevention of transmission of pathogens across intra- and inter-country borders warrants devising biosecurity measures at par with international standards. International guidelines are developed by WHO, FAO and OIE (OIE, 2020) in respect of human, plant and animal pests and pandemics. For handling the most dangerous transboundary pests more of BSL-III and BSL-IV laboratories in the country are required to ensure biosafety, biosecurity and biocontainment. Biosecurity needs to be observed from farm to national to regional and international levels in a bottom-up approach. Farm level biosecurity practices are available for crops, cattle, sheep, pig, poultry and fish production systems with best designs in terms of phyto/zoo sanitary measures such as quarantine, rodent and vector control, disinfection of animal sheds and premises, proper disposal of dung, urine, feed and fodder wastes and proper carcass disposal for effective management of infectious diseases although ground level adherence is still wanting. India needs to take a look into its biosecurity preparedness and plug all the big gaps to prevent being blindsided to dangerous biological agents either man-made or natural. A number of biosecurity preparedness measures applicable for zoonotic and human diseases, have implications for plant quarantine, which is lagging behind leading to a cascade of invasive pests affecting field and horticultural crops.