Eaten hollow

The sal heartwood borer is all set to destroy sal forests in Madhya Pradesh. But this would not have been possible without the assistance of an incompetent forest bureaucracy and an indifferent scientific community. Their answer to the crisis was as bad as the problem: large-scale felling of infested trees

By Jitendra Verma
Last Updated: Sunday 07 June 2015

Eaten hollow

-- (Credit: Photographs: Rajni Kant Yadav<)in the dense forest of Amarkantak, district Shahdol, Madhya Pradesh (mp) , where the river Narmada originates, the gurgle of the stream was difficult to hear amidst the monotonous sound of axes falling on giant sal trees (Shorea robusta). But for the timely intervention of Saifuddin Soz, Union minister of environment and forests (mef), about one million sal trees would have been cut in the state to prevent further infestation of trees by the sal heartwood borer (Hoplocerambyx spinicornis), a pest endemic to the region. However, by the third week of January, half-a-million trees had already succumbed to the axe before the minister could intercede.

Over one-sixth of the total sal forests in mp have been affected by the epidemic that has spread to six districts, covering an area of 300,000 hectares (ha). (ha). This includes Kanha National Park, the biggest tiger reserve in the country. In Mandla, the worst affected district, about 800,000 trees have been attacked. The total loss is estimated to be Rs 250 crore. Privately, forest officials admit that the number of trees slated to be cut is grossly underestimated. The present sal borer attack began in 1995, and would not have acquired epidemic proportions but for the inaction of the forest bureaucracy. By the time the state forest officials woke up, it was too late. The final solution according to the foresters: cut down all infected trees.

The axing was a low-key affair till Shiv Netam, mp's minister of forest, was forced to inform the state legislative assembly in November 1997 about the drastic step. The opposition cried foul. A public interest petition was filed in the mp High Court. The mef constituted a committee headed by B N Gupta, director-general, Indian Council of Forest Research Education (icfre) , Dehradun, to investigate the cause of the epidemic, the extent of damage, and to suggest remedial measures. mp forest officials claim they had written to the icfre several times without any response.

Prodded by New Delhi, the committee visited the affected areas in district Mandla and conducted "extensive discussions" on December 14-16, 1997. The committee felt that the problem is of a serious nature but there is no need for "panic". On the other hand, the committee members who visited Jabalpur and Mandla said that the situation is "out of control". They warned that if preventive measures are not implemented in time, the situation may aggravate. The committee supported the large-scale felling of sal trees as the only way to ensure that the larvae die out, preventing yet another, larger cycle of infestation with the onset of the monsoon.

But a senior forest official, speaking "off the record", said that the committee report was wanting on the scientific aspects of the pestilence. Ram Prasad, director, Indian Institute of Forest Management (iifm), Bhopal, who is a member of the committee, refused to sign the final report. He alleged that he was not consulted before it was written. Doubts persist in the state about the failure of experts from premier forest institutes to develop safer alternatives, especially since the pest is endemic to the region. Prasad told Down To Earth: "Instead of straightaway cutting the trees, the forest officials could have looked for alternatives."

Not all forest officials agree with the "final solution". "They should have discussed the problem elaborately and searched for alternatives," says a senior forest official in Bhopal who did not want to be named. "It seems that the forest officials were more interested in cutting the trees than finding alternatives," says Prasad. State forest officials also drew flak from non-governmental organisations (ngos). Samar Singh, secretary general of World Wide Fund for Nature (wwf) India, says: "In this day and age when science has made so much progress, it is indeed sad that solutions other than large-scale felling of trees have not been suggested by experts."

Following wide criticism of the committee, a task force of environmentalists and foresters has been appointed by the mef on January 14 to take a fresh look at the sal borer menace. The task force will give its report within a month. Meanwhile, the formation of a steering committee to suggest long-term solutions was also announced on January 14, 1998. Ironically, the steering committee includes all but one of the members who were in the earlier committee headed by Gupta. The environment minister called a meeting of experts on January 14 that severely criticised the report submitted by the Gupta committee.

The Gupta committee's argument that if affected trees are not removed before the monsoon, it would lead to a further spread of the pest also fails to stand its ground. Prasad insists that insects and pathogens are not the primary factors behind sal mortality. "Their role is only secondary, after the complex interaction among climatic, biotic and management factors have debilitated the trees," he says. According to officials, the sal borer started to emerge in the third week of June 1997 when the conditions were optimum - humidity was 91 per cent and temperature was 28 c. Hence, it is essential to know more about the pest and its victim.

Sal and its borer: a profile
The sal borer has not come out of the blue. Come monsoon, the adult sal borer emerges from hibernation, starting another battle with the sal tree. The larvae bore into the tree trunk, eating it up till they reach the heartwood. This battle continues year after year.

The sal tree produces resin that attracts the insect. The borer feeds on the tree, breeds on it, and has adapted its life cycle to the specific features of the tree. With the onset of the monsoon, the adult beetle emerges from the pupa and the female lays, on an average, 250 eggs in the bark of the tree. The eggs hatch in seven days. The larvae remain active for six-seven months (from June to November), gnawing into the innards of the tree, the whitish sap wood, and the red-brown heartwood. The larvae form galleries, eating their way in and out, up and down the stem of the tree.

The larvae enter into the pupa stage and stay within the tree till the onset of next monsoon. The normal life span of the beetle is three to four weeks - insects from the early swarms die even when the later swarms are emerging. Adult beetles are strongly attracted by the smell of fresh sap and have been known to fly to newly felled trees up to 0.8 km away within five minutes. They can smell the sap from a distance of 2 km.

The sal tree has its own defensive mechanism. Up to a certain number, the tree drowns the larvae in their tunnels by exuding resin and drowning 85 to 100 per cent of the larvae. But the excretion of resin weakens the tree itself, making it more susceptible to subsequent attacks. Hence, when the larvae attack in large numbers and the points of attack are numerous, the tree cannot produce resin in sufficient quantity and succumbs to the attack. This outflow of resin forms the very obvious and familiar yellow trickle (ral) seen in most sal forests.

Writing in the forest bulletin titled Hoplocerambyx spinicornis - An important pest of sal in 1926, D J Atkinson, officiating forest entomologist at the Forest Research Institute (fri), Dehradun, made some interesting observations about the nature of the relationship between the sal tree and the borer. "It is curious how frequently one finds ral mentioned in working plans, but how rarely it is associated with the presence of Hoplocerambyx or of any other insect... Working plans mention it as a curious phenomenon productive of a certain amount of revenue as a minor forest product - it is used in Central Provinces (now Madhya Pradesh), apparently, to make incense and probably for torches - but do not expatiate on a probable or possible cause for it," he observed.

"It is in fact... the result of the natural retaliation of the trees to the punctures of Hoplocerambyx larvae, and is, consequently, the first warning that the insect is active in the forest and engaged in attacking standing trees. Its presence, when unaccompanied by other symptoms of attack, such as wood dust and splitting bark, is usually indicative of the fact that the tree has successfully withstood the attack and is on the road to recovery... The writer has never taken a living larva from under the splash of ral - the galleries always end after an inch or so and careful search will reveal the entombed corpse or head of the little larva."

Forest officials, when contacted by Down To Earth , did not reveal any knowledge of these characteristics. With such a great deal of entomological information available about the sal tree and the borer in the archives of fri and the frequent nature of the problem, it is appalling that no scientific research institute in India has come out with alternative measures to deal with it.

What went wrong
The insect attack started in December 1995 in Dindori and east Mandla divisions, according to forest officials. Local people, certain field officials, and activists from local ngos, however, point out that the insect attack was detected way back in 1992. But the delay in taking action by forest officials has led to the epidemic.

"The pest is in the larval stage at present and remains deep in the heartwood. Chemical measures were neither found effective nor practical," says Anil Oberoi, chief conservator of forest (ccf) in Jabalpur, who is coordinating operations in the affected districts.

The only method to control the insect - as suggested by icfre and fri - is catching and killing adult insects, using the "trap-tree operation." In this, trees between 60 cm and 90 cm in girth are selected as traps and are cut into 2.5-metre-long billets. The bark at the ends of the billets is loosened by beating with the head of an axe. This provides a hiding place for the borer that is attracted to the billet by the resin.

In 1997, about 15,100,000 adult insects were killed by labourers. The department gave 75 paise for every beetle caught. But labourers say that the insects were only killed on the records of forest officials. Bhaskar Raman, resident of Nainpur and an activist with the National Institute of Woman, Child and Youth Development (niwcyd), an ngo , shares the view. "The money has gone into unknown pockets," he says. According to Balram Verma, a resident of Mandla: "The labourers lost interest when the department revised the rate at 25 paise per insect. This led to a rapid rise in the insect population. The rate was restored when the chief minister visited Mandla on September 9, 1997.


In the name of affected trees, the forest department is also cutting healthy trees, says Anadi, resident of Mandla. A forest guard recently transferred to Mandla from Bastar complained that the marking of affected trees has not been done properly. Labourers marking the trees do not know how to differentiate between affected and non-affected trees, resulting in rampant felling of good trees, says Madhav Prasad Shukla, resident of Mandla. T N Maharishi, former chief conservator of forest (ccf) has the same complaint. "This shows the negligence of the forest department. Despite detecting the pest onslaught in 1995, they did not take the problem seriously," he says.

Oberoi disagrees. "We are completely transparent and every thing is being done in a proper manner, free from any malpractice," he says. At present, 15,000 labourers have been deployed in the operation, he points out. However, Oberoi says that it may take two or three years to completely control the problem.

Lessons gone a-begging
The "final solution" shows that the forest officials have learnt precious little from history. Going by the accounts in noted forest journals and the department's own reports, mp has a history of sal borer attacks. The attack of sal borer is considered an epidemic when the trees affected by the insect are more than one per cent of the total number.

The insect was first noticed as a pest of sal in 1899. Since then several epidemics have been recorded. In 1923-28, the sal heartwood borer was observed in the Mandla forest division and adjoining sal forests of the state, in which 7,000,000 sal trees were affected. At that time about 4,28,000 adult insects were killed and 3,87,500 trees felled and removed from affected forests. In 1950-51, there was another attack in Mandla, and in Hoshangabad 1959-62 (see table: Major sal borer attacks in India).

With such a history of sal borer attacks, there is a surprising absence of any scientific forest management practices. India's forest department and research institutes have no contingency plans to anticipate the problem and be prepared. Hectares and hectares of forests are destroyed each year, not only due to human activity, but also by pests, fires and soil erosion. Recently, about 100,000 deodar trees in district Shimla, Himachal Pradesh, have been affected by a pest known as the deodar defoliator (Ectropis deodarae). Would this be a replay of the sal borer episode? The rate of regeneration of our forests is quite low. How long can we afford the incompetence of our foresters?

Major sal borer attacks in India
State Forests/division/range Area infested (sq km) Year No/value of trees affected
Assam Goalpara, Amosi Not available 1906,1961,1961 Not available
Bihar Palamu
60 trees
Himachal Pradesh Nahan 85 1948,1954 6,955 Rs.4,00,000
Madhya Pradesh Balaghat
Supkhar & Baihar
Supkhar & Mukki

South Mandla


Not Available
70,00,000 (Rs.1,37,50,000)
Uttar Pradesh Dehradun





Not Available
(Rs 1,82,800)
Not Available
Not Available
Not Available

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