Mode of Damage & Management Techniques for Termites
- Abu Bakar Siddique
- Sajid Sarwar
- Shajar Khalil
Termites are serious pests for plants and trees, as well as for buildings and wooden structures. They cause serious damage and loss to the farmer. Buildings are also infested which is alarming. To get rid of termites some physical, chemical and biological control measures are adopted. Excessive use of chemicals makes the termites more resistant and pollute the environment, which causes skin cancer and other serious diseases. Now to make the control more effective and to secure the environment physical and biological strategies are being applied
Subterranean, Dry wood, Crops, Buildings, Physical, Chemical, Biological control
Where termites have great importance in maintaining soil fertility and nutritional balance, there they have also a problematic aspects for human beings. Termites damage our crops, buildings and woody products. They have 2800 described species yet, 185 species have been declared as pests. They damage over 3 billion of cost woody material in the U.S. Hodotermitidae, kalotermitidae, rhinotermitidae, termitidae, procornitermes cause severe attack in agriculture. Termites are social insects, labor division exists. Their colony consists of queen, male, drone, sterile and workers. 3000 eggs per day can be lay down due to their large abdomen. Eggs color is yellowish white, hatched after 50-60 days of incubation. Colony matures after 4-5 years, consists of 60,000-200,000 individuals which are naturally workers. Workers and soldiers are of 6mm length, head is creamy white, equal to half length of body. Workers and soldiers are mostly wingless and blind.
Termites are of pale color, soft bodied, chewing and biting mouth parts which uses cellulose as food. They are blind, belonging to order Isoptera. Closely relating to cockroaches. That is why they are long living social insect pests. In the colony, they feed on woody material, dead plant matter and decaying material. In the colony, male continuously mate to get the secretions to regulate or maintain the individuals. Workers and soldiers come to maturity in a year, but worker live for 3-5 and soldiers 5 years. In April-May nuptial flights are held to mate, this is the indication of 1st swarming. Soon after mating, female being followed by male, search for a site to lay. Where she looks a wooden moisture place, royal chamber is made up and eggs are laid.
Taxonomically, termites are classified into Isoptera order. 2800 species and 7 families are introduced yet. They have been arranged in phylogenic sequence.
Damage (agricultural crops);
Seedling species; termite make mounds near the source of food in moist soil. Major galleries comprises of many sub-galleries which divert 50m away from one another to forage directly from the lower side of the seedlings. Termites cut down the seedlings just below the surface.
Mature species; O.wallonensis is a species of termite that have severe attack on maturing and matured plants. The mounds having separated galleries which leads to the chamber in the mound. Termites directly attack on the roots, as result, water and nutrient provision to plant is blocked. Which makes the pathogens more active. When roots are being fed internally, they become weak. The plant falls to the ground and die.
Maize; O.wallonensis species attack on the mature maize crop not on the pre-mature. Roots are safe from infestation till the maturation of the crop. Termite damage the plant from lower side to a few cm up and downward. The outer covering of plant is not infested and covered with soil layer. But the inner side is infested totally and is filled with soil, when wind blows, plant falls down.
Ground nut; same species attack on the ground nut, from tap root towards stem internal damage is done. Outer covering remains safe and sound and contains 5cm soil cover on it. Pods are also be attacked on, by breaking the outer shell. Low rainy areas face such problem. Termite kill the plant by various ways, by removing the outer soft cover of the pod, due to internal attack the plant have lack of nutrient and water provision, so the plant wilt and finally dies.
Sugarcane; sugarcane grows up from setts. Termite attack primarily on the initial level on the sets, which results stunted growth. Secondary attack takes place, when termites meet the holes on the cane, made by borers and some rodents. By penetrating, termite damage and feed on the soft internal part of the cane. Mostly this attack is reported in the rainy season. Infested canes have low juice quality and low weight. Termite attack internally, cut off the central leaf which results serious yield loss.
Soya bean; root stubbles are the main habitat of termites in the field. Termite become active from stubbles and attack on the roots of soya bean plants. Feed on internal material and tend to weaken the plant which leads to the yield loss.
Coconut trees; coconut seedlings are more damaged by termites in the nurseries and the mostly the transplanted one. Termite slightly bite on the growing points of the seedlings, then there is serious loss. Mud galleries nurseries are also damaged. Tender shoots get infested by termites which cause serious loss.
Wheat; O.wallonensis is the species that attacks the wheat on all the stages even under controlled conditions. 6-40% wheat damage is caused only due to termites.
Millet; the stubbles provide food and shelter to hide the termites out of season. They come out of stubbles when there is new crop has been sown. Lower side of the leaves are infested earlier. Soil sheeting of shoots is seen in the millet when they are mature.
Mango; mango trees are also infested by O.wallonensis species of termites. They establish themselves under the hard covering of mango tree, producing an earthen sheet outside. Which indicates their presence.
Eucalyptus; 10-15 years old trees are damaged by the species O.wallonensis. Infestation is detected by the earthen sheet produced outside the trunk.
Damage (buildings, structures)
Garden; garden also face the termite attack, fences in the gardens are infested by termites which degrades the whole garden.
Wooden structures; besides agricultural crops, termites also damage the wooden structures, windows and doors of the buildings. Infestation is indicated by the presence of soil excretion.
Floor; termites attack the laminated floorings. As a result blisters and wrinkles can be seen.
Wall; termites take cellulose from the wooden wall and make invisible cracks in the walls, sometimes they are visible.
Foundation; foundations of the buildings are also be damaged by termites. No doubt, termites do not eat concrete, but they find cracks in the concrete base and reach inside the buildings where, there are wooden windows, doors and ceilings are present to be damaged.
No doubt, termites are decomposers of plant and woody material. But they become dangerous when they attack on crops and buildings. So, to get rid of termites some controlling measures are adopted.
Crop rotation; termites hide themselves in the stubbles of harvested crops. They dormant in the stubbles and become again active when the same crop is again sown. So, to get rid of termites, crop rotation should be adopted.
Toxic barriers; a physical method to control termites from attacking on woody material. Termiticides are used in the soil around the targeted structure. Chlorfenapyr treated barrier is very useful, because it is non repellent and toxic. In Australia, chemical treated base and border is created below and under the building structure, which is to be saved.
Non-toxic barriers; in non-toxic barriers, sand and polythene sheet are used. Because they are impenetrable. They hinder the penetration of termites in buildings, stores etc. concrete slabs are also a kind of non-toxic physical barriers. Aluminum sheets, graded particles, granites and steel mesh are also non-toxic physical barriers. Steel mesh works well, it should be used in the base as well as over the soil surface, it must be felt.
Heating; alternate method of chemical fumigation. Whole house is covered by nylon traps, heat sensitive objects are removed from building, and water is set on running in the plastic pipes to avoid melting. Warm air is blown for 30 minutes at 450 and for 1 hour at 500C.
Freezing; not too much effective in larger areas. Traps are used in the building before chilling it. Liquid nitrogen is used in this technique, chilled out at -20F to freeze the termites inside. Later the traps are removed.
Electrical technique; in this technique, attacked wooden material is treated. An electric gun is fitted on the other side of infested wood and current of ~0.5 amp, 90,000v and up to 60,000 cycles, is passed. Termites are killed.
Microwave; in this technique, generators are used which are controlled by remote. Generator is fitted with a pole at 1 foot distance from the infested wall. Generators produce heat, termites are killed and then generator with pole is removed.
In chemical control a wide range of Termiticides are being used, such as; cypermethrin, fipronil, permethrin, imidacloprid, methrin are used internationally as products of different brands. Local chemicals are also used but they have some toxic ingredients in them which cause architectural influences (Scheffrahn et al., 1997).
Soil, after treating with bifenthrin, cypermethrin (>50ppm) is most active against termites. While treated with permethrin and chlorpyriphos (<50ppm) reacts slowly. Fenvalerate and isophenphos (<100ppm) have negligible reaction.
Treated wood; coated with 10% CaCo3 in solution of gelatin, 5% CuSo4 prevents termites attack for 2, 4 years long. Subterranean termites are kept away by Termiticides injections, which are applied in the basis of walls. It prevents termites attack years and years. Methyl bromide, a beneficial which discourages the formation of bromine, as bromine consumes the ozone layer. Bromine reacts 50% more than Cl in consuming the O3.
No doubt, chemicals are being used excessively on broad level. But they are not eco-friendly, our environment is polluted and facing serious diseases now. So, to secure the environment researchers are working on biological techniques.
Plant oils; this technique was introduced in early 1972. Kukus grass oil is most effective against subterranean termites, because it repels and fumigates some pesticidal fumes. Which affect the termites. It also acts as a barrier for red fire ants. Leaf, root and wood extracts are also anti-termite.
Nematode; nematodes have 2 families; Steinernematidae and Heterorhabditidae are parasite of termites. Used in biological control, nematode on infective stage inserts symbiotic bacteria in the body of insect’s host, which leads to death. Nematodes are soil living organisms, they can directly attack the termites by introducing them in the mounds.
Bacterial; hydrogen cyanide is toxic to termites, which is produced in the soil by some rhizobacterial species.