Warning locust warrants no panic

Dr G K Mahapatro and R Gavas*

This write up is a rejoinder to an article, Lockdown, Locusts and Laudable Lessons, published on 1^st June 2020 in SMART AGRIPOST. Two serious concerns relevant to locust invasion in Indian context are covered herein.

 Waves of swarms to sweep states

Trouble is brewing, thousand miles away from mainland of India. The latest FAO Desert Locust Bulletin (No. 500, 4 June), is out hardly 4-5 days back. The situation during the month of May and the prediction until mid-July are presented therein. Scenario is like this, spring bred locust army (hopper bands and swarms) swept Southern Iran, and Baluchistan, Indus valley, Punjab of Pak land. Huge area treatment was done in more than 1 lakh and 75K ha land, respectively in both the regions. Immature swarms arrived early in Rajasthan and some in northern states of India (>50K ha area treated). The FAO forecasts that spring-bred swarms formed in southern Iran, and southwest Pak, migrate to Indo-Pak border, in order to breed with the unset of monsoon. Before going back via Rajasthan in late June, swarms are to oscillate, in northern states mostly. However, swarms from Africa (Somalia Penisula) will arrive from early July-onwards.

Locust Warning Organization will press 25 drones into service, buy 60 more vehicle-mounted chemical spraying machines to counter incoming locust invasion, as apprehended with the monsoon winds from the Arabian Sea to destroy Kharif crops, in late June and early July. Around 800 tracta-mount sprayers were reportedly already being used in Rajasthan.

No need of panicking

More than two lakh square kilometers of vast swath of land comes under Schedule Desert Area (SDA) in India, which is the summer breeding ground for desert locust. Locust Warning Organization and 10 Locust Circle Offices (LCO) of Government of India located in Rajasthan and Gujarat do take necessary monitoring, survey and control in such SDAs in coordination with State Governments.

Advisories for locust survey and control were communicated to relevant state governments. For locust outside SDAs, temporary control camps of LCOs were established in Chittorgarh, Dausa, Jaipur (Rajasthan); Neemuch, Ujjain, Sheopur (MP) and Jhansi (UP). States of MP and Maharashtra wherein small swarms incursions were located in few districts, necessary control campaigns were carried, deploying tractor-mount sprayers and fire-tender vehicles. The Central Integrated Pest Management Centres are instructed to liaison with States, and extend necessary technical inputs, and sensitize their agriculture field staff and functionaries. Adopting standard operating procedures (SOPs) and contingency plans for locust survey and control were communicated to states.  List of items and norms of assistance under State Disaster Response Fund (SDRF) and National Disaster Response Fund (NDRF), were intimated to all State Chief Secretaries by the Central government.

In this backdrop, the advanced preparedness of states like Odisha, has created some confusion and panic, on the imminent invasion of locust in the State.

It is in this light, we clarify few doubts. A clear understanding of the life cycle of desert locust is key to visualize things judiciously. Maximum damage to vegetation is inflicted by the pink swarms (immature adult locusts). They are called fledglings, the immature adults; they pass this stage within two weeks to sexual-mature adults. Obviously, even if there is a swarm incursion into Indian territory, this will take minimum 10-15 days to reach Odisha border (as locust migrates @ 150 km/day, Odisha is far away from Indo-Pak border, ca.1500-2000km). By the time the swarm, even if reached Odisha (in extreme case), the fledglings (pink swarm) will pass to mature adults, that may cause lesser damage. They will tend to lay eggs in right moisture regime and may not prefer inland soils of Odisha (they prefer wet sandy/sandy-loam soil). Thus the potential threat is much diminished. Moreover, even if stray swarms divert towards Odisha, there will be several control interventions, during its path by other State governments. South Indian states are not predicted to be under threat by FAO.

Locust look-alike Grasshoppers Cause Panic

Across various social media including print and visual media, there were numerous news and reports about locust-like grasshoppers in Odisha, Karnataka, Kerala, Maharashtra, AP, Meghalaya etc. We received some queries both in our Vegetable Farmers Forum, ICAR-AICRP on Fruits (Entomologists group) and independently from various parts of the country, via social media. Recently in a webinar on Locust menace in India organized by ICAR, on 30^th May 2020, Dr Chandish Ballal, Director of NBAIIR, Bengaluru, an entomologist in the panel, informed that large groups of grasshoppers were spotted by public in some pockets of Karnataka. This had caused confusion among the general public and many approached the scientists to decipher its identity. It was confirmed not as desert locust but other grasshoppers.

Taxonomic truth

Spotted grasshopper (Aularches miliaris)

Both desert locust and spotted grasshoppers are insects that belong to class- Insecta, Order- Orthoptera, and suborder Caelifera (short horned grasshoppers). The short horned grasshopper that caught public awe and attention was identified as Aularches miliaris, a member of family Pyrgomorphidae. This family contains about 500 species distributed globally with quite a few of them serious pests. Commonly referred to as gaudy or bush grasshoppers these colorful grasshoppers show aposematic coloration. A glance through all the old literatures dating back from 1898 till date, which are available in public domain, mentions this as spotted locust or coffee locust. Some more synonyms are coffee spotted grasshopper, ghost grasshopper, northern spotted grasshopper and foam grasshopper, and enjoys some popularity as a pet insect. Out of sheer interest, junior author collected second and 3^rd nymphal stages of this grasshopper from farmers’ field and reared them to adulthood in captivity.  We share here few catchy clips of the distinct stages of this beautiful insect, for giving awareness to the panicked public. This will surely help in separating them from the international trans-boundary pest locust (Schistocerca gregaria).

Nymphs, molting to adult and fully adult stage(s) of spotted grasshopper (captivity & field study, Kerala)

Adults of Aularches miliaris are bright colored, a sort of warning to its intended predators of their distaste. Adults have black head, yellow tuberculate thorax, greenish forewings with yellow spots and a black and red-banded abdomen. Nymphs are blackish with yellow markings.

(Spotted grasshopper, nymph and an adult (Pulppally, Wayanadu, Kerala)

Mistaking spotted grasshopper swarms as early signs of desert locust

Odisha: State TV channels telecasted sensitizing clips, locust like insects invading and denuding one kilometer stretch tract of vegetation (forest trees like Kendu, Sal) in Nilagiri of Balasore district.  The local people pointed that these insects are yet to form their wings, and apprehended its invasion to nearby crop fields, in winged adult stage. Good thing, some vernacular newspapers clarified the doubts in public mind, in their news capsules, as effective mass media. Latest, in Redhakhol (Sambalpur district), grasshoppers were reported devouring Aak plants in some newspapers. We also received photo-clips of grasshopper eaten crops bordering forest lands, in Kalahandi district, but not the insect.

Andhra Pradesh: Outbreaks of spotted grasshopper nymphs were seen in Gokivanipalem ( Atcherla Mandal) . They heavily fed on cashew and other plants.

(Hopper band of spotted grasshopper on cashew  (Gokivanipalem, AP)

Tamil Nadu: Spotted grasshopper, Bombay locust, and Crytacanthacris tatarica (Cotton grasshopper) species have mistaken for desert locust.  They were attacking banana and rubber plantation crops in Poovankodu and Viyanur in Kanyakumari district bordering Kerala. It was earlier observed by a farmer in Khandal near Udhagamandalam as reported in media. Aak grasshopper is reported in Neelalagiri, as aired online media and YouTube.

Kerala: Recently Wayanad, Pathanamthitta, Idukki and Kottayam districts had witnessed heavy outbreaks of spotted grasshoppers. Spotted grasshoppers at times become a major sporadic pests and a list of outbreaks of these as a pest species in the past three decades in Kerala alone is listed, gleaning olden records.

 Past Three Decade Pest status – outbreaks of spotted grasshopper in Kerala

(a)Mango, (b) teak – damaged by Aularches miliaris

(Pulpally, Wayanad)

Karnataka: Aularches miliaris was reported from Puttur and Coorg districts of Karnataka state feeding on rubber, banana, chromalaena etc.

Meghalaya: On June 5, 2020 outbreaks of spotted grasshopper, Aularches miliaris was reported from Ghasi hills on Banana through social media. Many social media groups mistook it for desert locust. The confusion was cleared by actively passing information about the pest (Aularches miliaris) into these groups and to scientists.

Maharashtra: Independently received clips from KVK, Narayangaon by us, implies visually that in that area (70 km away from Pune), the insect in question is probably spotted grasshopper, not desert locust. Obviously, as small parts of Maharashtra were already invaded by locust swarms, the public may go panic.

 Habits of grasshoppers are different from locust

No taxonomic distinction exists between locust and grasshopper species; the basis for which is whether a species forms swarms under conducive conditions, or not. Grasshoppers swarms in October, to breed, on bushes and grasses. They are heavy, sluggish, and capable of short jumps (hops) only. On capture, as disturbed emits sharp rasping noise from the thorax, when pinched, squirts a clear off smelling viscous mucus with a bitter taste, slightly alkaline with bubbles. This protective foam comes out as a strong jet from thorax; the foam heaps up around the insect submerging the insect partially, as a protective cover. Contrary, locusts are having no such system, rather are edible, have been eaten throughout the history and are considered a delicacy in certain civilization (Iran, China etc) to satiate the taste buds.

Pest Status – Spotted grasshopper is reported as a  polyphagous pest of several crop as well as wild plants. Across its range, A. miliaris is recorded as a pest of coffee, banana, arecanut (Areca catechu), coconut, teak, dadap (Erythrina lithosperma), mango, cardamom, cassava, castor, durian, guava, maize, mango, mulberry, oil palm, rice, sugar cane, chilies, cocoa, cotton, custard apple, jute, pigeon pea, rubber, sesame, sorghum and pine, causing economic damage to these and many other crops. Coming to its pest status, although it was reported as a minor  pest causing occasional economic damage, changed pest status, on current background must be revisited, to allay some unscientific assessments that spotted grasshopper causes zero economic loss.

Severe outbreak sand debilitating crop damages by spotted grasshopper, which were reported from Bangladesh (attacking mango, guava, wild trees etc.) and Sri Lanka (on coconut, cassava, coffee, teak etc.)  our neighboring countries, confirm its pestiferous nature.

Not control, but conservation needed!!

It is claimed that Zoo Outreach Organization, Coimbatore, India in 1998 did Local Assessment of spotted locust, Aularches miliaris and proposed to designate it as a lower risk near-threatened taxon, based on informal field sightings & indirect information channels. International Union for Conservation of Nature and Natural Resources (IUCN) Red List and Species Survival Commission websites does not contain any information pertaining to Aularches miliaris designated as such. When contacted, IUCN has informed that “Aularches miliaris has not yet been formally assessed on the Red List and information on this species is not included in the IUCN database”. This strongly points to the need of conducting periodical assessments to remove ambiguities about its status, as no subsequent reassessments were done, even after 22 years. The said assessment should be done based on strong scientific methodologies by a dedicated group of scientists from Agriculture and Conservation science, systematically.

Spotted grasshopper thrives well in forest ecosystem. They migrate towards cropped lands and cause often severe defoliation to standing crops. The damages are mostly irreversible and can become a serious deterrent to attain its potential yield, especially in annual crops of like banana. As a pest, causing economic loss to banana, cardamom, coffee farmers – it is a matter of concern in Kerala. It is in this context that antifeedant (neem-oil, a.i. azardirachtin 300 ppm), biological agents (entomo-fungal Beauveria bassiana, Metarhizium species) and entomo-pathogenic nematodes were recommended, so as to reduce the damage in an eco-friendly manner and to help conserve the species, same time. At its peaks, population may be controlled by tilling the area where they deposit their egg pods or manually collecting the grasshoppers. Pesticides are effective but better be avoided; they are hazardous to environment, cause collateral damage to other non-target organisms.  Botanicals may be used to repel them from cropped areas. Basically, they may act as pest, consuming the seedling stage crop plants, which can best be deterred by neem-derivatives. The reported wild and concentrated attacks of forest areas in Kerala, Odisha and erstwhile, may be treated carefully, for possible cropland invasion.

Aak Grasshooper or Calotropis grasshopper (Poekilocerus pictus)

It is a large brightly colored grasshopper under Pyrgomorphidae family. They also exhibit warning coloration, nymphs are notorious for squirting a jet of liquid to long distances when disturbed and grasped. Under highly favorable conditions and preferred host plants their number can shoot up and can cause damages to crops. Heavy outbreaks of this grasshopper was recently reported from Tamil Nadu, Andrha Pradesh (Anantpur district) and occasional occurrence in Odisha (Redhakhol, Sambalpur district)  in May, 2020.

Concluding comments

It is time, for us to ponder why such changing pestilence is observed this year, though these grasshoppers were very much in our system, since long. The global climate change forces us, to revisit our priorities; pest status of A. miliaris and other grasshoppers, IUCN threatened status for former one – all once again. Thanks to our Vegetable Farmers Forum (www.smartagripost.com, 23-May), via which we could collect crucial news capsules and photoclips, compile comprehensively the current crisis of misreporting of desert locust in various states, other than the scheduled desert areas. Only 20 species, out of 7000 known grasshoppers, transform into gregarious swarm form. All grasshoppers are not locust. No need of panic, in case of reported grasshoppers in few states as stated.

We received remarks from reputed entomologists of India, on our previous article published on 1-June. It is anticipated that south-west monsoon wind currents may not allow swarms going further to eastern parts of India. Inland breeding is remote as most such states do not have sandy/ sandy-loam soil for oviposition. Pesticide applications on crops are ecological concern for imbalanced natural enemy fauna. Much hailed and sought after botanicals and biopesticidal stocks are limited to cater the massive demand coming on our way. The next successive waves of swarms may threat the next kharif crops in India. Certainly, we need robust forewarning systems, on satellite imagery-based ground truth estimates, with GPS coordination. Realism remains in prevention of buildup of locust swarms, and curtailing the swarm incursion and movement inwards through surgical strikes, at correct time as suggested in our previous published paper (www.smartagripost.com, 1-June).

Lucidly, Matt Simon (www.wired.com/science, 2-May) narrated the terrifying science behind the locust plague of Africa. This worst outbreak is after 25 years, near plague like situation. It is predicted a 500-fold increase in massive locust population by June 2020, in the horn of Africa (Somalia, Ethiopia, Kenya – Somalia peninsula), an extreme alarming situation. There is an exponential growth of 20-fold in each generation in conducive climate, and this has added to the current locust situation, since last one to two years, the prevailing climate, erratic rainfall with prolonged monsoon has created this critical crisis. International FAO expert Dr Cressman commented, that locust problem originated from south Oman somewhere in 2018, from remote most part of our planet, where there is no road, no infrastructure, no network nothing, but only towering sand dunes as tall as skyscrapers.

The global climate change, and erratic rain pattern with prolonged monsoon has provided everywhere the conducive condition, not only to desert locust, but also other grasshoppers. Consequently, in various parts of Indian states, such cases are reported recently. Few farmers, stating that they never confronted such situation earlier in their lifetime, only provoke us to comment that, this unique situation repeated after a long 26-years stretch only.

We as true world citizens are committed in our actions for conservation of biodiversity, same time with necessary control intervention for locust invasion, in relevant cases.

(Authors are working in ICAR-IARI, Regional Station, Pune, Maharashtra and *Kerala Agricultural University, Banana Research Station, Kannara, Thrissur respectively. Views expressed are personal. They can be reached by emails: gagan_gk@rediffmail.com and gavash.ragesh@kau.in, for feedback and comments.)

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