Learn about the pests that damage brinjal and its control.
1. Brinjal Lacewing Bug, Urentius Sentis Distant (Hemiptera: Tingidae):
The lace-wing bug is distributed in the northwestern parts of the Indian Sub-continent and is common in the plains. Except for brinjal, it has not been recorded feeding on any other plant. Both the nymphs and adults are destructive. The full-grown nymphs are about 2 mm long and 1.35 mm broad.
They are pale ochraceous and are stoutly built, with very prominent spines. The adult bugs measure about 3 mm in length and are straw coloured on the dorsal side and black on the ventral side. On the pronotum and wings, there is a network of markings and veins.
Life-Cycle:
The pest is active from April to October and hibernates as an adult from November-March in cracks and crevices in the soil under the brinjal plants or other protected places. The bugs live for 30-40 days and lay 35-44 shining white nipple-shaped eggs singly in the tissues on the underside of the leaves.
The eggs hatch in 3-12 days and the young nymphs feed gregariously on the lower surface of the leaves, but the fully-developed nymphs are found feeding and moving about individually on the lower surface as well as on the upper surface. They grow through five stages and transform themselves into adults in 10-23 days. The insect passes through 8 overlapping generations in a year.
Damage:
The damage caused by this insect is very characteristic. The adults and the nymphs suck the sap from leaves and cause yellowish spots which, together with the black scale-like excreta deposited by them, impart a characteristic mottled appearance to the infested leaves. The pest is most abundant in August-September. When the attack is severe, about 50 per cent of the crop may be destroyed.
Control:
Apply one litre of dimethoate 30EC in 325 litres of water per ha.
2. Brinjal Fruit and Shoot Borer, Leucinodes Orbonalis Guenee (Lepidoptera: Pyralidae):
This pest of brinjal fruits and shoots is widely distributed in Malaysia, Myanmar, Sri Lanka, India, Pakistan, Germany and East Africa. Besides brinjal, it has also been recorded feeding on many other solanaceous plants and occasionally on the green pods of peas also.
The damage is done by the caterpillars which are creamy white when young, but light pink when full-grown. They measure about 18-23 mm in length. The moth is white but has pale brown or black spots on the dorsum of the thorax and abdomen.
Its wings are white with a pinkish or bluish tinge and are ringed with small hair along the apical and anal margins. The fore wings are ornamented with a number of black, pale and light brown spots. The moth measures about 20-22 mm across the spread wings.
Life-Cycle:
The caterpillars hibernate in winter and pupate early in spring. The moths appear in March-April and during their life span of 2-5 days, lay 80-120 creamy white eggs, singly or in batches of 2-4 on the underside of leaves, on green stem, flower buds or the calyces of fruits.
The eggs hatch in 3-6 days and the young caterpillars bore into tender shoots near the growing points into flower buds or into the fruits. When available, the latter are preferred to the other parts and one caterpillar may destroy as many as 4-6 fruits. The larvae grow through 5 stages and are full- fed in 9-28 days.
The mature larvae come out of their feeding tunnels and pupate in tough silken cocoons among the fallen leaves. The pupal stage lasts 6-17 days and the life-cycle is completed in 20-43 days during the- active season. There are five overlapping generations in a year.
The parasitoids associated with larvae of this pest are Pristomerus testaceus Mori, and Cremastus flavoorbitalis Cam. (Ichneumonidae), Bracon sp., Shirakia schoenobii Vier and Iphiaulax sp. (Braconidae).
Damage:
When the terminal shoots are attacked, the growing points are killed. Damage to the fruits, particularly in the autumn, is very severe and it is not uncommon to see the whole of the crop destroyed by the borers.
Control:
(i) Remove and destroy all the affected shoots and fruits with borers inside.
(ii) Avoid continuous cropping of brinjal crop.
(iii) Do not ratoon the brinjal crop.
(iv) Spray 3-4 times at 2-week interval using 250-300 litres of water per ha with any one of the following insecticides as soon as the attack starts:
(a) Organophosphcites:
Two litres of quinalphos 25EC, 1.4 litres of monocrotophos 36SL, 1.25 litres of triazophos 40EC.
(b) Carbamate:
Two kg of carbaryl 50 WP.
(c) Synthetic Pyrethroids:
250 ml of fenvalerate 20EC, 100 ml of permethrin 50EC, 500 ml of cypermethrin 10EC, 400 ml of decamethrin 2.8EC. Insecticides of same group should not be used repeatedly in order to avoid development of pesticide resistance and appearance of secondary pests. A waiting period of 7 days should be observed after the spray.
3. Brinjal Stem Borer, Euzophera Perticella Ragnot (Lepidoptera: Pyralidae):
The stem-borer is a minor pest of brinjal and is widely distributed in India. It may also attack chillies (Capsicum annum L.), potato and tomato plants.
Damage is caused by the caterpillars which measure about 20-22 mm in length, when full- grown. They are creamy white and have a few bristly hairs. Their bodies taper posteriorly. The moths measure about 32 mm across the spread wings and have pale-yellow abdomens. The head and thorax are greyish, the fore wings are pale straw-yellow and the hind wings are whitish.
Life-Cycle:
This pest is active from March to October and passes the winter as a hibernating caterpillar in the stems of old plants. The overwintered larvae pupate at the beginning of March and emerge as moths in the second half of the month. The moths are active at night when they mate and lay cream-coloured scale like eggs singly or in batches on the underside of young leaves or in the axils of young branches.
A single female may lay 104-363 eggs in its life span of about a week. The eggs hatch in 3-10 days and the young larvae feed for a few minutes on exposed parts of plants before boring into the stem where they feed on the pith by making longitudinal tunnels. They pass through 4 or 5 stages and are full-fed in 26-58 days.
When full-grown, they make silken cocoons within the feeding galleries or in the cracks and crevices in the soil. After pupation, they transform themselves into adults in 6-8 days. The life-cycle is completed in 35-76 days and the pest has 5-6 overlapping generations in a year.
The larvae are parasitized by Pristomerus testaceus Mori, and P. euzopherae Vier (Ichneumonidae).
Damage:
The caterpillars feed exclusively in the main stem and have never been observed to bore into the fruits. As a result of their attack in the field, stray plants are seen withering and drying up.
Control:
(i) When the attack of this borer is serious, the ratooning of brinjal plants should be discontinued. The withered plants should be uprooted and burnt.
(ii) Four sprays of 500 ml of malathion 50EC or 315 ml of dichlorvos 100 EC in 325 litres of water per ha should be given at 15- day intervals.
4. Brinjal Hadda Beetles, Henosepilachna Dodecastigma (Wiedemann) and H. vigintioctopunctata (Fabricius) (Coleoptera: Cocdnellidae):
Two species of hadda beetles, viz., Henosepilachna dodecastigma and H. vigintioctopunctata, attack different solanaceous vegetables like brinjal, tomato and potato. Another species, Epilachna demurili, attacks cucurbitaceous vegetables exclusively.
Damage is caused by the beetles as well as by the grubs. Beetles of all the three species are about 8-9 mm in length and 5-6 mm in width. H. vigintioc-topunctata beetles are deep red and usually have 7-14 black spots on each elytron whose tip is somewhat pointed.
Beetles of H. dodecastigma are deep copper-coloured and have six black spots on each elytron whose tip is more rounded. E. demurili beetles have a dull appearance and are light copper-coloured. Each of their elytron bears six black spots surrounded by yellowish rings.
Grubs of all the three species are about 6 mm long, yellowish in colour and have six rows of long branched spines.
Life-Cycle:
The life cycle and mode of damage of the three species of hadda beetles are very similar. Considering their abundance, H. vigintioctopunctata is the most important. It passes the winter as a hibernating adult among heaps of dry plants or in cracks and crevices in the soil.
It resumes activity during March-April and lays yellow cigar-shaped eggs, mostly on the underside of leaves, in batches of 5-40 each. A single female can lay up to 400 eggs in her lifetime. The eggs hatch in 5, 3.3 and 2.9 days at 25, 30 and 35°C, respectively. The grubs feed on the lower epidermis of leaves and are full-grown in 17.8, 8.7 and 7.1 days at 25, 30 and 35°C, respectively.
The pupae are darker and are found fixed on the leaves, stems and, most commonly, at the base of the plants. The pupal stage lasts 13.4, 6.7 and 5.1 days at 25, 30 and 35°C, respectively. The pest passes through several broods from March to October and its population is at a maximum at the end of April or in early May. During the hot and dry months, the number declines greatly but the population again builds up in August.
Eggs are parasitized by Tetrastichus ovulorum Ferr. and Chrysonotomyia appannai L. (Eulophidae) while Pleurotropis epilachnae Rohw., P. foveolatus C., Chrysocharis johnsoni S. Rao, Solindenia vermai Bhet and Tetrastichus sp. (Eulophidae) parasitize the larvae, and Pediobius foveolatus (J.C. Crawford) (Eulophidae) parasitize the pupae.
Damage:
Both the adults and grubs cause damage by feeding on the upper surface of leaves. They eat up regular areas of the leaf tissue, leaving parallel bands of uneaten tissue in between. The leaves, thus, present a lace-like appearance. They turn brown, dry up and fall off and completely skeletonize the plants.
Control:
(i) Collect and destroy the infested leaves along with insects in the initial stages.
(ii) Varieties like Arkashirsh, Hissar, Sel. 1-4 and Shankar Vijai have shown resistance to this insect.
(iii) Spray 625 ml of malathion 50EC or 2.5 kg of carbaryl 50WP in 325 litres of water per ha, at 10 day intervals as soon as the pest appears.