Details :


M.M.Hossain* and M.K.Tripathy**

College of Forestry

 Orissa University of Agriculture and Technology, Bhubaneswar-751003, Odisha, India
E-mail of Author(s) :;

*Dean; **Associate Professor


India as well as Odisha is endowed with  vast forest  cover  of  70.17  m ha      (21.34 %) and 05.04 m ha (32.34 %), respectively as per Forest Survey of India Report (2015).  However, as per Report of the Committee on Forestry for alleviation of Poverty says only 40% of this is actually covered under tree cover (Anon. 1984).  Forest cover is decreasing due to increase in fuel wood requirement, round timber requirement for construction, agricultural implements and for meeting the day to day changing lifestyle of human being. Forestry has now come out of its traditional operational areas  i.e., reserved forest and now areas like canal banks, farm pond bonds, cultivated land bonds are also brought by several fast growing tree covers. This also leads to introduction of several exotic species like Acacia mangium, Eucalyptus spp. and plantings are taken in monoculture rather than mixed culture where productivity is reportedly low i.e.,  0.61 m3/ha/yr., which may be accompanied by slow growth of traditional forest tree species apart from natural forest plantation. Pest problems are major biological determinants of forest productivity when natural ecosystems are drastically altered by clear felling with either a single or a mixture of few tree species specially exotics insect pest problems, are vigorously aggravated. There are several examples of abandonment  of the entire plantations programme because of insect epidemics  (Beeson 1941).

            In a country like India, due to conducive climatic conditions and stable as well as undisturbed ecology of forests, high reproductive potential of pests, more forest insects multiplies vigorously which are not even regulated by natural factors like predators, parasites, diseases etc. However, unfortunately no authentic estimate is available regarding monetary loss caused by insect pests in forests.

            Since the major forest insect pest problems will be encountered in afforested      i.e., manmade plantations it is necessary to understand biocoenose in manmade plantations which will vary over space and time. The kinds of crops, cultural practices, land use pattern, vegetational complexity and weather are important elements affecting the degree of stability of biocoenose (Sen Sarma, 1986). Everything except weather can be manipulated by human being to cause a rise or fall in insect population. However, quantity and quality of food supplies, effectiveness of natural enemies, competition for food and spaces and abiotic factors like relative humidity, temperature, rainfall, draoght etc., also affects the biocoenose. In plantations various types of pests viz. key pests, occasional pests or potential pests may be present simultaneously. Another factors favors pest situation in manmade plantations that large clear felled areas creates more unfavorable situation for the speedy inhabitation of original natural energy complex in contrast to small clear felled areas in the mid of forest land where reinvasion of original natural enemies takes place speedily. In natural forests each organism is involved in a number of food chains, but in clear felled areas with initial stages of plantation of seedlings it reduces food resources of numerous heterotrophic organisms of original forests including vertebrate predators. Some adult entomophagus insects also depend on nectar of many wild flowers of understory which is not met in manmade plantations. Introduction of monocultures of exotics like Acacia mangium and Eucalyptus spp. further adds complexity in the ecosystem. Some insects which are otherwise less important assume serious pest states in these plantations.

            So, trees can be considered as a part of complex ecology and the actual damage caused by the insects is very difficult to assess. Heavy leaf loss either by insects or by disease may not be extreme when averaged over the life of the trees and boring to the wood or shoot may not be a cause of concern as in  many cases the tree may survive the damage and produce a marketable product. If pest management tactics have a financial implications then to achieve a realistic cost benefit analysis it is crucial to have some quantitative implication regarding economic damage is being done by a pest, so as to adopt cheaper control measures. However, this knowledge is inadequate and in fact in many countries, active research programmes is going on to evolve long term monitoring methods and impact data related to pest density. It might be available for a small number of trees or  insect associations particularly in developed countries. Insects that are utilizing tree resources can be categorized into several types (Speight and Evans, 2004) as mentioned below..


(A)  Defoliators :

Insect groups :- Larvae of moths (Lepidoptera) and Sawflies (Hymenoptera), Nymphs & adults of grasshoppers (Orthoptera) and beetles (Coleoptera).

Activity                :- Leaves can be eaten partially or enitirely or the epidermises between the veins removed (skeletonisation or leaf mining).

Primary impact :– Wider deleterious effects, these include shoot and root growth loss, reductions in height and volume increment, reduction in flowering or seed set. For a single time defoliation, the tree may recover but in repeated defoliation the tree may dies. It is difficult to assess the impact.

Secondary impact  :- The vigor is reduced and natural defense against herbivores is reduced leading to attack by several secondary pests like borers of lepidoptera and coleoptera. These may be killed subsequently due to stem girdling.

Example                  :       Teak defoliator ( Hyblaea puera, Hyblaedae)

                                        Teak skeletoniser (Eutectona mecharalis, Pyralidae)

                                        Shisham defoliater ( Plecoptera reflexa, Noctuidae)

                                        Gambhar skeletoniser ( Calopepla leayana, Chrysomelidae)

                                        Pongamia leaf miner (Acrocercops sp., Gracillaridae)


(B)   Sap feeders :


Insect groups     :-  Nymphs and adults of bugs (Hemiptera, Suborder- Homoptera) aphids, psyllids, scale, mealy bugs, spittlebugs, cow bugs etc.


Activity           :- Removal of phloem or less commonly xylem sap or plant cell                                    content.


Primary impact :- Removal of primary production syntheses and organic nitrogen  compounds from the tree causing a significant reduction in yield and equal losses like that of defoliation. There may be direct loss of foliages due to injection of saliva along with toxins by the feeding insect.


Secondary impact :- Local leaf mortality and losses are same like chewing defoliation. Sometimes causes bud and  bark necroses allowing invasion by pathogenic fungi.


Example :          Tendu  Psyllid (Trioza obsoleta; Psyllidae)

                             Alstonia psyllid ( Pauropsylla tuberculata ; Psyllidae)

                            Teak membracid (Cosmoscrata relata ; Membracidae)

                            Teak Pentatomid  (Agonoscelis pubercula; Pentatomidae)



(C)  Shoot borers :

Insect groups :- Larvae of moths (Lepidoptera, Torticidae, Pyralidae), Larvae and adult beetles (Scolytidae),  Shoot beetles, Curculionidae).

Activity :- Tunneling inside growing shoots usually leaders followed by secondaries. Size of tunnel increases as the insect grows and develops.

Primary impact :- Death of attacked shoot followed by cessation of growth in young trees. Older saplings may give rise to one or more secondary branches. Tree becomes bushy and dead headed.

Secondary impact :- Timbers became bent and forked and fails to attend expected height.

Example :  Mahogany shoot borer (Hypsipyla spp. ; Pyralidae)

                   Bamboo hespene borer (Estigmena chinensis;  Chrysomelidae)

                   Gambhar shoot weevil  (Alcidodes ludificator;  Curculionidae)


(D)   Bark feeders :

Insect groups :-  Larvae of moths Lepidoptera, (Cossidae, Metarbelidae)

Adult weevils  (Curculionidae) , Termites  (Isoptera).


Activity :- Both larvae and adult weevils feed on bark materials making shallow tunnels which sometimes also reaches inner layer. In younger plants bark may be removed completely.

Primary impact :-  Local bark necrosis, death of young seedlings. Frequent attack by termites may causes death of young transplants as in Eucalyptus spp. 

        Examples :                     

                                    Termites (Odontotermus odobesus; Termitidae)

                                    Pine weevil ( Hylobius abietis;  Curculionidae)

                                    Simul bark feeder ( Inderbela sp. ; Metarbelidae)


(E)  Bark borers :

Insect groups :- Grubs and adults of beetles of family, scolytidae, platypodidae, Cerambycidae, Buprestidae,

Activity :- Both adults and larvae lays eggs on bark surface or in maternal galleries, excavated in sap wood portion. Larval tunnels increases in size with growth of larvae. Pupation occurs there, adult emergence take place through characteristic exit hole; non vigorous trees are more likely to be attacked.

Primary impact :- Species specific patterns of engraving of galleries on sap woods and may cause death in severe incidence, because of ill health, secondary pest / and or disease attack is noticed in later stages. These dead trees act as future feeding and breeding site of borers.

Secondary impact :- Mass outbreak of same or related species is the likely resulting in complete failure of plantation programme.

Examples :

                      Southern pine beetle (Dendroctonus frontalis; Curculionidae)

          Acacia longicorn beetle (Xystrocera festiva;  Cerambycidae)

(F)   Wood borers :

Insect groups :- Larvae of moths belongs to Hapialidae (swift moth), Cossidae (goat moths), Zeuzeridae (redborers), Larvae of beetles belongs to cerambycidae (round headed borers) Buprestidae,( flat headed borers), Larvae of wood wasp (Siricidae, Hymenoptera).

Activity :- Larvae tunnels from outside leaving a wound on the bark surface. Tunnels may be extended within the surface of timber or in the centre of heart wood.

Primary impact :- Serious degradation of timber; although the tree appears healthy outwardly, the economic value is degraded. Termite and swift moth attack  is through physical wound (insisted  due to fire,  pruning or fungal infection), wood wasp and some beetle attack is secondary due to stress condition.

Example :        

                        Beehole borer of teak ( Xyleutes ceramica; Cossidae)

           Sal heart wood borer (  Haplocerambyx spinicornis;                     


             Acacia root and shoot borer (Celosterna  scrabrator ;


                         Teak sapling borer      (Sahyadrasus  malabaricus ;

                                                                    Hapialidae )

             Teak trunk borer (Cossia cadambae ; Cossidae)


(G) Root feeders :

Insect groups :- Termites, Grubs of Scarabaedae or Melolonthidae (White grubs and cockchafers), Curculionidae (vine weevils), Noctuidae of Lepidoptera (cutworms), Some termite species.

Activity :- They feeds on barks of root portion of young transplants leading to mortality, Eucalyptus is highly susceptible.

Primary impact :- Young plants and small trees faced mortality soon after planting. Also it is a problem in industrial plantation sites.

Secondary impact :- Old trees may be attacked due to damage in earlier life particularly in nurseries.

Examples :      

                           Subterranean termites

                            White grubs ( Holotrichia serrata; Scarabaedae)

                            Cut worm (Agrotis ypsilon;  Noctuidae)


          Integrated Pest Management (IPM) has a variety of definitions and for a particular crop pest interaction one or more appropriate pest management tactics are combined into a package for minimizing cost of production and environmental impacts along with maximizing profit. The two bedrock foundations are prevention and monitoring i.e., strive to avoid pest problem at the outset, but keep watch on the crop to avoid significant wrong happenings. This concept is now well spread to almost all types of crops and the increasing goal of growers who losses both quality and quantity is to the damaging organisms such as insects, diseases, weeds and nematodes. But in practice it is sometimes difficult to achieve full control.   

          In natural forests of India IPM is followed by nature in balancing the pest population but in afforested plantations and monoculture forests faced a lot of threat from insects. In forestry, economic,  IPM is considered as a preventive technique. It may not be possible to prevent pest outbreaks in local or industrial plantations owing to ecological, technological, social and economic reasons. So, it is vital to grow trees which will reduce the probability of serious pest incidence. So, the first step is to acquire knowledge on insect pest outbreaks and foresters should adopt technique so as to grow trees free from pest outbreak. Decline in tree health can be considered as the prime factor for insect pest and disease attack in all type of forests which is detailed below.

Causes for insect pest out break :

(1)   Attack by a primary pest

(2)   Damage at nursery stage

(3)   Dry soil

(4)   Infection by a primary pathogen

(5)   Occurrence of natural disasters like very cyclonic winds and prolonged drought  situation.

(6)   Old age of plants or overaged population

(7)   Over crowding

(8)   Poor and degraded soil condition which is a resultant of sever soil erosion due to  severe rainfall

(9)   Water logged condition leading to poor tree health

(10)           Wrong site species matching

(11)           Improper and detrimental management practices :- Damage during pruning, thinning due to improper methods and less sharpen equipments, under thinning, poor site selection leading to stress, planting nearer to pest reservoirs in older and / or natural stands, mishandling in nurseries, monoculturing, provision of pest reservoirs in thinning logs, use of susceptible species are also contributed much for pest incidence. These practices can be manipulated to avoid pest out break which is now grouped under Silvicultural (Ecological) control.           

Pest monitoring in forestry : T

          The most fundamental feature of IPM in forestry is the reliance on some form of monitoring procedure to advise the forester regarding possible pest outbreaks. It is based upon impact assessment of different methods, risk involved to all sectors and so on. A knowledge on threshold densities of important pests is highly required.  Use of pheromones for the purpose is used in Australia against important pests like five spined bark beetle (lps grandicolis), in USA against Douglas fir tussock moth (Orgyia pseundotsugae) and  against Lymantria dispar (Gypsy moth) , in Eastern Europe against nun moth (Lymantria monacha). For detection of southern pine beetle incidence in USA, air crafts being employed in aerial surveys. In India attempts are going on to synthesize sex pheromones in Eutectona mecharalis, Hyblea puera and few others important pest at Indian Council of Forest Research and Education (ICFRE), Dehradun and  Kerala Forestry Research Institute (KFRI). Presently, it is done manually by walk and watch method or by using light traps at several targeted centres.

Options in Integrated Pest Management :

           IPM in forestry requires a range of steps and distinguishes two final steps in pest management  i.e.,  prevention and cure. The ultimate aim is to develop prevention so that long term, sustainable population management can be achieved. However, all these depend on the quality of monitoring and decision making components of the system.  Emphasis should be given on maintenance of initial good tree vigor and if urgently required option for cure should be thought. The options are :-

I.              Silvicultural practices manipulation (prevention steps)

II.            Biological control (Curative steps)

III.           Chemical control  (if warranty of situation arises)


Silvicultural practices :

a)    Manipulation of host species and stand


Different species of trees and ages of trees differ in reaction to insect attack. Termites have special preference to Eucalyptas in a mixed plantation. So non target and preferred species can be grown along with Eucalyptas in termite prone areas. (Thakur et al., 1989). In mixed stand polyphagus species dominates over oligophagus or monophagus species. Mixed age stands can be produced by cutting adjacent areas at an interval of 15 m so that light demander species will come up. The most desirable plant species in understory of teak forest supporting 10-17 nos. of parasites of skeletoniser and defoliator are Anogeissus latifolia, Cassia fistula, Garuga pinnata, Grewia tiliafolia, Kydia calicina, Lagerstroemia parviflora, Butea monosperma, Shorea robusta, Sterculia villosa, Terminalia bellerica, Xylia xylocarpa. The most undesirable species in teak mixed forest is Lantana camera, Millingtonia hortensis, Premna latifolia, Vitex sp, Pterospermum, Gmelina arborea Callicarpa sp.  etc. The main plants may be infested severely by insects due to their presence .   


b)    Alternate host and ground cover manipulation

 Mixture of two different tree species at 15 to 30 m. width can hardly be able to check interexchange of winged insects and egg laying. Larval defoliators can not be spread from crown to crown. The incidence of attack of colar weevil (Pagiophleous longiclaris) in Mahogany is premierly determined by incident of attack on Toona ciliata. Teak cankergrub, Dihammus carvinus infestation on teak is determined by presence of Gambhar and  Clerodendron. Babool borer, (Celosterna scrabrator) may breed on Eucalyptas, Casuarina etc. (Sen Sarma  and Thakur, 1985).  Presence of dense undergrowth under Ailanthus excelsa reduce the infestation of shoot webber, (Attava fabriciella) because the insectivorus birds, natural parasites thrive there and the dropped larvae from plants gets obstruction for climbing the trees again. Incidence of teak skeletoniser and defoliator is more observed in plants with no underground cover (Jha and Sen Sarma, 2015). So, ground fire is not advocated for control of any forest pest including Haplocerambys spinicornics in sal rather increases the population of Cossia kadambae in teak present inside. To avoid severe incidence of borers in sal and sisoo, all the plants above or approaching rotation period should be clear felled from an area without leaving the stubbles to decay at the place. Another concept, entomological rotation period is to be calculated here. Before taking large scale afforestation programme, complete felling of the area is not advised as along with pests, predators and parasites will also be killed.


c)  Tree growth manipulation and density regulation

Annual thinning or annual coupe should aim to remove the severely infested trees or their parts. Regular thinning in young stand of Toona and Seemul can reduce the incidence of shoot borers (Hypsiphyla  robusta & Tonica niviferana, respectively). Thinning of dense area of bamboos can reduce weevil attack (Cyrtotrachelyx dux). Sal heart wood borer incidence can be reduced by regular thinning. Irrigation dates can be manipulated in Sissoo to avoid defoliator attack of Plecoptera reflexa.


d) Increasing host vigor and sanitation

Old and poorly maintained plantation invites more bark feeder pests as like in Seemul and others. More vigor trees can avoid or recover the pest attack quickly.

e)   Choice of Right species at right place

          Planting of Sissoo should be preferred in well drained and light textured fertile soil. Teak should not be planted adjacent to Gambhar or Clerodendron infertunatum. Bark beetle incidence in all trees are directly correlated with condition of planting soil.

f)   Maintenance of proper hygiene at felling site

          Felling should be preferably completed during winter months when all the insects are inactive and breeding is slow. Bark should be removed immediately to avoid the oviposition of pin hole borers, flat headed borers, round headed borers etc., Care should be taken for immediate disposal and destruction of remnant  of felling.

II.    Biological control  :

       It is considered as most appropriate method for forest pest control. Predators such as birds, small mammals and other insects can consume large no. of lepidopteran larvae, aphids etc., Parasites are also acting in their own ways. But in some situation the population reduction is not significant to reduce existing outbreaks. However, success stories are limited regarding utilization of predators and parasites for forest pests. Great spurce bark beetle Dendroctonus nicans in UK has been controlled by predatory beetle Rhizophagus grandis introduced from continental Europe. Success was recorded in 5-10 years. Cyprus aphid (Cinara sp) is controlled by parasitoid Pauesia juniperorum in Kenya and Malwi. Several microbial agents are also reported to be effective in controlling forest pests Beuvaria bassiana is used successfully to control white grubs in forest nurseries of China and India, (Nair 2001)

       Baccillus thuringiensis has been used on large scale by aerial spraying for control of defoliator caterpillars of forest trees in many developed countries since 1960. It is effectively used for control of temperate forest pests such as Douglas fir tussak moth, Spruce bud  worms, pine caterpillars, larch bud moth, Gypsy moth and fall worm has been used in limited way in tropical forestry of India and Thailand in commercial teak plantations by aerial spraying. The high cost involved in the practice has prevented its wider use (Hytacharern et al, 1993). The baculo virus particularly Nuclear polyhedrosis viruses (NPVs) are also found very effective in reducing leaf damage to 76% due to Hyblea puera attack in Teak in India (Nair et al, 1996). It was also found that HpNPV at 1000 LE / ha is highly feasible.  Among the others chitin synthesis inhibitors are also largely used for pest control in forestry in western European countries.

          In India work on natural enemies of two major teak pests i.e., defoliator and skeletoniser and their interaction to other pests has been studied in detail  as reported by Nair ( 2001) as given below :-

Major teak pest

Parasitoid of teak pest

Alternate host insect

Host plant



Hyblaea puera

Goniozus montanans

Striglona scitaria

Cassia fistula

Carcelia kockiana

Sylepta belteata

Cassia fistula

Eriborus gardhevi

Pilocrosis milvinalis

Cassia fistula

Paloxorista solennis

Catopsilla crocale

Cassia fistula

Elasmus brevicornis

Catopsilla crocale

Cassia fistula

Eutectona mecharalis

Apanteles mecharalis

Glyphodes conclusalis

Cassia fistula

Cedria paradoxa

Sylepta balteata

Cassia fistula


However, sudden appearance of the moths in mass along with immediate oviposition has limited the utilization of natural enemies. But study on the potential of some parasitoids like bethylids, eulophids, braconids and inhneumonids are in experimental stage (Nair et al., 1995).

III.        Chemical control :

It is the last option for use in forestry pest control. The less persistent insecticides with little damage to environment should be included in case of urgency. Those included in groups like Carbamates, Synthetic pyrethoids, botanicals including neem products should be given priority. The USDA, 1980 guidelines recommends several insecticides including organophosphates and carbamates for control of forest pests. But in todays era to avoid drift problems in pesticide applications, controlled droplet application (CDA) technique is used which minimizes volume of chemical use (ultra low volume-ULV) and a series of compounds belongs to several other groups with diversified mode of action is evolved which can be experimented from environment and cost effectiveness point of view particularly in developing countries. Special emphasis should be given on research for isolation and synthesis of pheromones for important forest pests to be employed both for mass trapping and population monitoring at different regions. It is problematic for chemical application in the growing trees, but in nurseries feasibility of chemical application is there and in all sectors, chemicals are applied to control soil dwelling, stem boring and foliage feeding insects of nurseries. When the number of transplants are too small it is advised to take caution, careful monitoring and assessment of impact of the situation before making large expenditure on chemical control operations. In India, air crafts were also used for small scale application of chemicals for control of insect  pests of teak. During 1965, seventy-six hectares of teak plantation in Keralaa was spread with endrin (Basu Choudhury, 1971) and 460 hectares of teak plantation in Madhya Pradesh was spread with carbaryl by air craft (Singh, 1985) successfully with single spray. But routine spraying with insecticide for forest pest control is not being carried out in India. In Thailand, neem extract containing 0.185% azadiractin applied at 200 – 300 ml per liter of sprayed fluid using a thermal fogger gave 79-99 % motility of larve of Hyblea puera in about 6 days (Eungwijarnpanya and  Yinchareon, 2002). In Costa Rica during late 1990, helicopter was used for application of chemical pesticides over teak plantation in 600 hectare of  area to control a new outbreak of Hyblaea puera. Research are going on for development of transgenic teak plants resistant to major defoliators in India by ICFRE, Deheradun and some of its sub centres located in the country.


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Source: OUAT Souvenir