Saving mango from mealy bug
By Dr R. A. Khan and Dr M. Ahsan
mealy bug is one of the most damaging insect pests severely attacking mango
crops throughout the Subcontinent. The insect lays eggs on soil close to mango
trees. The hatching of eggs starts with the rise in temperature in
January-February. The emerging lice like tiny nymphs travel via stem to reach
the fruiting parts to suck the sap. This causes immature fruit falling, and in
severe cases makes the trees completely devoid of fruits. At maturity, the
winged insects copulate with females at feeding sites and then the egg-carrying
females travel via stem to ground in April-May for laying eggs.
The measures used previously were only one way effective and could not control
the pest completely. The devise discussed here is new and is effective both ways
and controls the insect pests completely.
This trap is prepared using a narrow strip (8-10 inches wide and 6-12 inches
loose than the girth of the tree) made of thick, smooth and transparent “Shesha
plastic”. For its installation, the upper margin of plastic strip is erected
like a funnel around the tree while the lower margin is systematically rumpled
(to reduce its length) and tightly fixed on stem with nails. The lower fixed
margin is afterward covered with mud to arrest chances for the nymphs to escape
up through cracks and cervices on stem (See Fig.A). The traps are fixed on tree
stems almost 3-4 feet above the ground level.
During field research, this innovative technique has been proved to be the most
effective barrier against mango mealy bug nymphs crawling up the trees and
successfully entrap the egg-carrying females (each female carry 350-400 eggs)
while crawling down for egg laying in the soil during May. Powdered un-slaked
lime (2-3 inches layer) is placed in funnel of the trap has been found to
effectively kill the entrapped egg-carrying females.
The mango mealy bug some times directly fall on the ground due to shaking wind
therefore the trap should be kept active for two consecutive seasons from
January to May in order to achieve the best results. The funneled part of the
trap can be strengthened by passing a thin spring wire through narrow fold made
along upper margin of the funnel to fix it in position if the tree bole is of
larger size ( Fig.A).
Newly designed permanent funnel type slippery trap (made of stainless steel)
will soon be available in the Forestry Department of Faisalabad Agricultural
University.. These are made flexible to be fixed around the tree and will get
loose accordingly as the stem will gain width with the passage of time.
Previously used technologies “sticky band” (Fig.A 1) have become totally
ineffective for mango mealy bug since the passing over nymphs stick on glued
area in line, making a bridge for their companions to cross and reach the
fruiting parts. Accordingly the “slippery plastic band” (Fig.A 2) has been
observed to arrest only 60-70 per cent of the crawling up nymphs while the
remaining 30-40 per cent reaches the tree crown causing enormous fruit losses.
Fig.A : Position of funnel type slippery trap on the mango stem. Slippery and
sticky traps are also shown below. __
The effectiveness of this mechanical technique is wonderful since it works
both-ways. Studies have revealed that almost 84 per cent of the nymphs fall down
while crawling up over the wall of funnel type slippery trap. The escaped 16 per
cent insects reach fruiting bodies, mature there and copulated by winged males.
These 16 per cent insects are highly important since each of them carry 350-400
eggs. Funnel type slippery trap have edge over the old control techniques as it
entraps all these egg carrying females on their way back to the ground.
Courtesy: The Dawn