Insect management is a key requirement in the commercial forest practices. In this presentation few insect management practices are discussed with special reference to Eucalyptus, Tectona and SMahogany species. These species are common in the plantation industry in Sri lanka

1. Insect Management In
Commercial Forest
Management
Pabasara Gunawardane

2. Insects Pests Diseases

3. Kingdom : Animalia
Phylum : Arthropoda
Class : Insecta
Classification
Around 30 orders worldwide
More than one million different species of
insects have been identified, but some
experts believe that there may be as many
as 30 million insect species in the world that
have yet to be discovered and identified.

4. Dominant Orders Of Forest Pest Insects
• Coleoptera (beetles)
• Lepidoptera (moths and butterflies)
• Hymenoptera (ants, bees, and wasps)
• Hemiptera (bugs)
• Isoptera (termites)
• Orthoptera (grasshoppers and crickets)

5. The diversity of forest insects is also reflected in their
feeding habits.
• Leaf feeders
• Sap feeders
• Stem feeders
• Flower, nectar, pollen, and seed feeders
• Dead-wood feeders
Functional Diversity:
The Feeding Guilds

6. Plantation Species in Sri Lanka
• Teak - Tectona grandis (Verbenaceae)
• Eucalyptus
• Mahogany - Swietenia macrophylla
• Sandalwood – Santalum album
• Aquilaria

7. Tectona grandis
• Well known for its versatile timber
• Possesses several qualities - lightness and
strength, drying without warping and
splitting, easy workability and attractive
appearance
• Plantations of teak are estimated to
occupy an area of 5.7 million ha worldwide

8. Insects in Teak
174
Species
137
Leaf Feeders
16
Sap Feeders
14
Shoot/
Stem Feeders
5
Root Feeders
3
Seed Feeders
Nair et al 2007

9. Defoliators
Hyblaea puera
(Lepidoptera: Hyblaeidae)
• Defoliator insects cause severe defoliation
and, hence, reduce growth rate
• Outbreaks of these insects may occur 2 or 3
times during the growing season

10. Skeletonizer
Eutectona machaeralis
(Lepidoptera: Pyralidae)
• Its larva feeds on the green leaf tissue
between the network of veins, leaving the
skeleton of veins intact
• Partially damaged leaves are not shed and even
the fully skeletonized leaves are retained by the
tree for a long time

11. Stem borers
Zeuzera coffeae
(Lepidoptera : Cossidae)
• The most important stem borer in young teak plantations
• The larva bores into the pith of the stem of saplings and
ejects the frass through holes made on the stem

12. Stem borers
Xyleutes ceramicus
(Lepidoptera : Cossidae)
• Commonly called the teak bee hole borer
• Found in older Teak plantations
• The larva of this moth bores into the wood of living Teak
trees

13. Whitegrubs
Whitegrubs are the immature stages of some beetles of
the family Scarabaeidae (mostly of the subfamilies
Melolonthinae and Rutelinae)
• They live in soil and feed underground on the roots of
seedlings, grass etc.
• Holotrichia (syn. Lachnosterna) consanguinea and H.
serrata (Melolonthinae) are the common species found in
Teak nurseries in India and Sri Lanka
• The larvae bore into the fleshy taproot of Teak seedlings
and cause their death

14. Eucalyptus species (Myrtaceae)
• Eucalyptus is a widely planted tree genus in the
tropics
• The adaptability of eucalypts to a variety of site
conditions and their fast growth are major
characteristics
•The global area under eucalypt plantations is at
10 million ha

15. Insects in Eucalypts
920
Species
Nair et al 2007
Root feeders Defoliators Sap suckers Borers

16. The most common pest problem of exotic eucalypts is
mortality of saplings caused by root-feeding termites
Postelectrotermes militaris (Kalotermitidae) is found on the
heartwood of living trees of Eucalyptus sp. in Sri Lanka.
Eucalyptus Gall Wasp has been reported in Sri Lanka in 2010.

17. Swietenia species (Meliaceae)
Produces one of the world’s best furniture timbers
Swietenia macrophylla is the most widely distributed and
planted both in indigenous and exotic locations
Swietenia mahagony is also raised in plantations, but to a
much lesser extent
The plantations cover 151 000 ha worldwide

18. Mahogany Shoot Borer
Hypsipyla robusta
(Lepidoptera: Pyralidae)
• Saplings are the most susceptible to Hypsipyla attack
• Tunneling of the leading shoot kills the terminal growth,
resulting in the development of lateral shoots which may
also be attacked, causing a bushy top and loss of tree
form, in addition to growth loss
• It is suggested that the relatively low level of attack in
Sri Lanka may be due to good overhead shade where the
trees have been planted.

19. Sandalwod (Santalum album)
• Commercially and culturally important plant
species
• Sandalwood oil extracted from the
heartwood has high market demand
• Due to the high value and the demand, there
is a growing attention at present in
establishing sandalwood plantations

20. Insects in Sandalwood
150+Species
60
Leaf Feeders
92
Sap Feeders
6
Stem Feeders
5
Bark/Deadwood
Feeders
3
Seed Feeders
Remadevi et al 2012

21. Insects in Sandalwood
Sandalwood seedlings in the nurseries are subjected mainly to
the attack by defoliators and sap suckers
Cryptothecia cramerii (Psychidae: Lepidoptera) cuts off young
plants
Stem borers – Zeuzera coffease (red borer) Indarbela quardinotata
(bark-feeding caterpillar) and Aristobia octofasiculata (heartwood
borer) are some of the pests causing considerable damage to
living trees

22. Agarwood (Aquilaria Species)
Agarwood (Family -Thymelaeaceae) is one of the most prized non-
timber forest product traded in the international market
The establishment of forest species producing agarwood is gaining
attention at international and local levels

23. Insects in Agarwood
In agar plantation no such serious pests and diseases have been
observed
Heortia vitessoides - a leaf-eating caterpillar is considered to be the
most destructive pest causing damage by complete defoliation of agar
plantations
The intensity of attack is more in the trees grown in open than under
shade

24. Pest control
• Commonly used term for attempts to limit the
damage caused by pests
• Tried to kill the pest insects using chemical or
other means
• it was not easy to kill off the insects; they
reappeared when the effect of the insecticide
waned or developed resistance to the chemicals

25. Pest Management
• Planters realized that pests need to be controlled
only if they cause economic damage
• The term ‘pest management ’ was therefore coined
to indicate management of the pest population to
limit it to a tolerable level
•The emphasis was on regulating the population size,
not killing all the pest insects, which was
impracticable anyway

26. Historical Pest Management
• Traditionally, forest managers in the tropics have
ignored insect pest problems
• Main reason was the lack of scientific researches
• Research in tropical forest entomology is about a
century old
• A sound foundation of basic knowledge on insects
associated with forest trees has been built up over
time
• But, very few practical problems have been
addressed

27. Integrated Pest Management (IPM)
• The concept of ‘integrated pest management ’ emerged in
the 1970s
• It envisaged the use of all the available techniques in an
integrated manner to reduce the economic damage caused by
pests with the least ill effects on the environment
• IPM aims at regulating all the pest species including insects,
pathogens and weeds in a crop production system
•IPM marks a change in human attitude or philosophy, from
supremacy over nature to acceptance of an ecologically
compatible strategy to contain the pests

28. Tools of Integrated Pest Management
• Monitoring (scouting)
• Identification
• The threshold level
• Management Strategy – (Do nothing, Cultural
management, Mechanical management, Pesticides)
• Evaluation

29. Monitoring (scouting)
• Monitoring (scouting) forests and newly established
plantations will help detect problems early, while there
is still time to take action
• A representative sample of trees can be checked for
signs and symptoms of insect and disease problems
• All parts of the tree should be inspected from top to
bottom and from branch tips to trunk
• Depending on the pest, the use of traps or
microscopic examination may improve the information
gathered by visual examination

30. Identification
• Identification of pests and the diagnosis of pest damage
are key elements of IPM
• What kind of pest is present?
• What stage of the pest is present?
• What is the size of the pest population?
• How much damage has occurred?
• How much damage is likely to occur if no control measures are
taken?
• Does the pest or damage require immediate attention, or can
control measures be postponed until the trees are near harvest?

31. Threshold Level
• The threshold level - the point at which the pest or its
damage becomes unacceptable
• The threshold level may be related to the beauty, health,
or economic value of the tree crop
• Once the threshold level has been reached, determination
of the type of control procedure is needed
• Several factors are considered here (The size of the pest
population, the kind of damage the pest is causing, and the control measures that
are available and the cost effectiveness of potential controls)

32. Management Strategy
• Decision on management (control) strategies
• Do nothing - pest does not damage the crop value or the crop
value is so low
• Cultural management - manipulates the environment to make
it more favorable for the plant and less favorable for the pest
(good site selection, planting resistant varieties, or selective
pruning)
Mechanical management - Some measures exclude or remove
the pest from the habitat (Mechanical traps, screens, fences, and nets
can remove the pest or prevent access by the pest)

33. Management Strategy
• Biological management - Biological controls include the
beneficial predators, parasites and pathogens that kill
pests
• Pesticides - Pesticides are a very important tool in IPM
when large pest populations threaten high-value trees
- Knowledge of the pest’s life cycle, selection of an
appropriate pesticide, proper timing of the application, and
use of the right application equipment will improve
coverage and effectiveness

34. Evaluation
• The results of management strategies are evaluated
• This information will determine whether any follow-up
treatment is needed and will improve the management
strategies for the future
• Sound IPM practices pay off both economically and
environmentally

35. • Preventive measures - aim to keep pest
populations at low densities and not allow them to
develop into outbreaks
• In the case of teak defoliator outbreaks, destroying the early epicenter
populations during the pre-monsoon period can prevent at least part of the
subsequent large-scale outbreaks
• Retention of plant species that support alternative hosts of pest insects
• Reduce pest build-up by enhancing natural enemy action
• Use of pest-resistant trees
Two approaches are available for pest management

36. Remedial measures
Aim to reduce the pest population level by killing the
insects by one means or other
• Use of insecticides
- control of root-feeding termites of eucalypt saplings,
where the insecticide is mixed with the soil to kill the
termites that might attempt to penetrate to the tap root
- insecticidal treatment of nursery soil to control ants and
whitegrubs or mixing of insecticide with seeds while in
storage
- insecticides are applied to the insects and the trees after
the infestation is noticed
• Biological control with predators and parasitoids

37. Use of transgenic trees - An emerging method of pest management is
use of transgenic or genetically modified trees which possess genes
conferring insect resistance
Natural outbreaks of virus diseases are common in many forest insects
Causes sudden collapse of population outbreaks as in the case of the
teak defoliator Hyblaea puera
Such disease epizootics are usually caused by baculoviruses
Use of Semiochemicals (behaviour-inducing chemicals)

38. Existing management methods for
Mahogany shoot borer
• Mixed or enrichment plantings
• Wider spacing
• Varying tree density
• Provision of shade
• Promoting vigorous tree growth
• Encouraging natural enemies
• Leaving weed rows between young plantations
• Few systemic insecticides like carbofuran and Deltamethrin are
occasionally used. But these insecticides have limited prospects in
today’s pest management practices due to environmental concerns

39. Existing management methods for
Termites
• Several termiticides containing active ingredients: bifenthrin,
chlorfenapyr, cypermethrin, fipronil, imadacloprid and permethrin
are used
• New methods of termite control are always being developed by
researchers
• Plant derived natural products, entomopathogenic fungi are
some of the alternative methods

40. Constraints To Forest Pest Management
• Small number of forest entomologists compared to the large number
of pest problems
• Lack of adequate training of entomologists in applied research and in
the principles and techniques of pest management
• Inapplicability of sophisticated pest management methods employed
in developed countries, such as ultra-low volume aerial application of
insecticides, aerial release of biocontrol agents, computer-based pest
prediction and alert systems, due to technological and economic
constraints
• In most tropical countries forests are predominantly government
owned, and forest pest management has low priority relative to the
more pressing agricultural pest problems

41. Recommendations
• Increasing the research and monitoring of pest outbreaks
• Reformation of the forestry research institute to develop suitable
plant species
• Establishment of rules and regulations when importing plant species
• Conducting more research on biological treatments
• The ability to recognize beneficial biocontrol organisms, combined
with cultural and mechanical controls, may allow to reduce, delay, or
eliminate pesticide treatment of a minor pest problem

42. References
Nair, K. S. S , (2007) Tropical Forest Insect Pests, Cambridge University Press
Nair, K. S. S, (2001) Pest out breaks in tropical forests, Center for international forestry research
Mohd Farid Mamat , (2011) Costs and Benefits Analysis of Aquilaria Species on Plantation for
Agarwood Production in Malaysia
Remadevi O.K. (2012) Pests and diseases of sandalwood plants in nurseries and their management
Sandy Perry, (2000) Forest Pest Management, Michigan State University
Howard F. W. (2014) Mahogany shoot borer, University of Florida
Apichart Kaosa-ard (2010) Overview of problems in teak plantation establishment, Forest Resources
Department, Chiang Mai University, Thailand
Pest problems in forests available at
http://shodhganga.inflibnet.ac.in/bitstream/10603/6175/4/04_chapter%201.pdf as at 0220 hr.
25.08.2015
Indian Council of Forestry Research and Education, Dehradun. Sandal (Santalum album Linn.).
Dehradun, Forest Research Institute. 9p.