Life Cycle and Control Measures of forest Insects found in Nepal's Forest

The life cycle and control measures of the forest insect would be discussed here. The information followed the pattern of Forest Insect Scientific Name (Order of Insect, Family) and Common Name.

Forest Insect Scientific Name	Order	Family	Common Name
Apriona cinerea Chevrolet	Coleoptera	Cerambycidae	Poplar Stem Borer
Plecoptera reflexa	Lepidoptera	Noctuidae	Sissoo Defoliator
Clostera fulgurita	Lepidoptera	Notodontidae	Poplar Defoliators
Ectropis deodarae	Lepidoptera	Geometridae	Deodar Defoliator
Eutectona machacralis	Lepidoptera	Pyralidae	Teak Leaf Skeletonizer
Hypsipyla robusta	Lepidoptera	Pyralidae	Toon Shoot Borer
Hoplocerambyx spinicornis	Coleoptera	Cerambycidae	Sal Heartwood Borer
Hymenochaete  rubiginosa

Life Cycle and Control Measures of Apriona Cinerea and Plecoptera reflexa are discussed in detail.

Life Cycle of Apriona Cinerea and its Control Measures

Pic.: Apriona cinerea Source: Wikipedia

Common Name: POPLAR STEM BORER 

Scientic Name: Apriona cinerea Chevrolet 

Order, Family: Coleoptera; Cerambycidae

Distribution:

A. cinerea is indigenous to the west Himalayan ranges of Nepal and adjoining areas of India and Pakistan.

Host Plants:

The major hosts of A. cinerea belong to the family Salicaceae(in particular Populus and Salix) and to Morus, Ficus, Prunus, and Pyrus species.

Life History:

• Beetle- Elongate, 26 -50mm in length, narrow, greyish to greyish-yellow, on the anterior side of elytra there is dense pubescence, the undersurface is black. 
• The antenna is slightly longer than the body. 
• The prothorax is wider than long, the sides are produced medially into a long spine pointing outwards. 
• Elytra is shouldered.

Egg:

• Elongate – oval in shape, 7-8 mm long 3-3.2 mm wide, dirty creamish white, rounded at both ends, the cephalic end is broader than the other. Incubation period 5-7 days. 
• Eggs are laid on the upper portion of the main stem or branch. 
• The beetle peels a flap of bark and deposit one egg and seal the flap to conceal the egg. Incubation period 10-12 days.

Larva:

Creamy white in color, elongate, cylindrical, 60-70 mm long. Max. width at thorax 12mm. 

The young larva bore down the stem and make an ejection hole at an interval of 10 cm. 

The frass is accumulated at the base of the plant. 

Larval period 16 -20 months. 

Pupa:

• Extra or free, pale yellow in colour gradually darken at the time of maturity. Length – 50 mm and width 18 mm. 
• Pupal period 18 -22 days. In young plants larva can not complete their life feeding on the stem so it bores down to the roots and pupate there. 
• In older plants, pupation takes place inside the main stem only. 
• The pupal chamber is oval, elongated, at the end of the larval tunnel and the entrance is plugged by long wood fibers or frass. 

Life Cycle and Generations:

The beetle completes one life cycle in two years.

Nature of Damage:

• The main damage associated with Apriona spp. is caused by the larvae, which bore into the wood soon after hatching, creating long tunnels. 
• Several larvae may be found in a tree. 
• This affects the growth of the trees and decreases the quantity and quality of the timber and longevity of the trees 
• The larvae bore down from the top of the stem to the roots. 
• Due to the larval feeding, the stem becomes hollow and week. 
• The young plants are outrightly killed. 
• In old plants, all the larvae feeding on the branches bore down the branches and gathered in the stem.
• Due to the larval feeding, the stem become week and in the event of strong wind it breaks. 

Control Measure/ Management:

Mechanical 

If the incidence is very low the affected plants should be uprooted and burnt in case of young plants. In old plants pruning of affected branches should be done after monsoon before the larva reaches the main stem. 

Chemical control

Injection of a saturated solution of paradichlorobezene in kerosene oil in the lowermost ejection hole, after plugging the ejection hole on the upper side of the stem by wet clay. In nursery application of 10 grams of thimet at the base of the plant after soil working.

Life Cycle of Plecoptera reflexa and its Control Measures

Common Name: Sissoo Defoliator

Scientific Name: Plecoptera reflexa 

Order, Family: Lepidoptera, Noctuidae

Pic.: Plecoptera reflexa Source: Wikipedia

Dalbergia sissoo is an important timber tree of plains and is raised not only in plantation in forest areas but also along the roadside as avenue. It often suffers from severe defoliators attack by Plecoptera reflexa and as it remains leafless for the greater part of growing season , the growth is affected.

Distribution:

The Plecopteral reflexa, defoliators is mainly found in India, but its range extends west as far as the central and northern parts of the coastal plains of Israel, Pakistan and Nepal in the presence of its host Dalbergia sissoo. 

Host Plants:

This moth is a serious pest in the irrigated plantations of Dalbergia sissoo and occasionally responsible for the epidemic defoliation. They are also considered as a pest of Dalbergia latifolia and Pterocarpus marsupium.

Egg:

• Each female starts laying eggs within 24 hours after her emergence. 
• The eggs up to 400 are laid at night on young leaves, usually one egg only per leaf. 
• The incubation period is 1-5 days.

Larva:

• The1st and 2nd instar caterpillars eat the lower epidermis and the inner tissues of the leaf, leaving the upper epidermis untouched. 
• The grown-up larvae do eat away the whole leaves leaving large midribs only. 
• They may leave small portions of leaves when the food is in plenty. 
• When there is a scarcity of food or the leaves available are small and tender even a 3rd instar the larva eats away the entire leaves. 
• The larval period varies with the temperature and quality of food. It is 10 days in the hot summer month, 13 days in spring and 20 days or more in autumn. 
• The larva undergoes 5 molts 

Pupa:

• Pupation takes place on the ground among leaves or rubbish or in loose soil or under the bark of old trees. 
• Pupal stage varies with season for5-7 days in hot summer and 8-11 days in autumn.

Adult:

 The forewing of the moth is grayish brown with oblique irregular bands and the underside is grayish-white. 

Wing expanse is 1.25”.

Life Cycle and Generations:

• The life cycle completes in 17-30 days. 
• 11 generations occur within the year. At a quicker rate of development as many as 13

Nature of Damage:

• The first generation moths appear in the beginning of March and defoliation by the first brood is generally not noticed. 
• Heavy defoliation takes place at the end of April and at the beginning of May . 
• The population of the pest increases in the hot the dry season of the year.

Control Measure/ Management:

Preventive Measures

1. Site factor 
2. Sub soil water, Irrigation, mixed plantation 
3. Thining: An early thinning produces a more favorable ratio between the pest population and the quantity of foliage per tree. 

•  A thinning that is too heavy or too long delayed produces coppice – shoots and root suckers which are undesirable.

4. Cuttings and sowing : Afforestation by means of wide spaced root and shoot cuttings (or stump planting) is preferable to dense line- sowing in trenches. 

• A thicket of seedlings provides a quantity of tender immature leaves and increase the population of the defoliator per acre considerably more than a crop of cuttings. 
• Sticky bands is applied in a narrow band around trunk of the tree and crown is shaken violently.

Control Measure

1. Silviculrural- Irrigation should be done to have early flush of leaves during the months of Feb.-March to desynchronize appearance of new leaves and emergence of moths. So, by the time moths emerge the leaves become old and are not eaten by the larvae. Only juvenile leaves are eaten. 

2. Mechanical Control- The often recommended Plecoptera mixture (Prepared by heating and stirring constantly till it becomes viscid, a mixture of coal tar 37.5, pitch or asphalt 12.5 dry soap 7.5 castor oil 10, alluvium (earth) 12 parts by weight) is applied in a narrow band around the trunk of the trees and then the crown is shaken violently. 

The larvae which fall on the ground are prevented by reascending the trees by the sticky bands. 

In this way a large population of the pest is destroyed. Remedial measures

 

3. Chemical Control- Ground spraying with 1-2 l bs of dieldrein or Endrin in 40 gallons of water per acre kills all the emerging moths if sprayed before the emergence of the moths. 

• Spraying with 1-2 l bs of Endrin 19.5 % in 100 gallons of water gives 100% mortality of larvae on the trees for at lest 5 consecutive days i.e. the larvae hatching out of the eggs after spraying are also killed. 
• The insecticide remains effective upto a fortnight to the extent of 80% mortality of larvae. 
• In the case of wide spread epidemic, aerial spray with 1.5 l bs. Of Endrin in 3 gallons of water per acre will kill all the feeding larvae and adult moths.