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High population of this bug results in the death of a plant with more
susceptibility among weaker plants as it has a high reproductive rate
with a female laying up to 600 eggs and producing up to 15 generations
per year. The bug has the ability to spread rapidly once introduced.
The pink hibiscus mealy bug is a serious threat to many plants in tropical
and subtropical parts of the world and can attack on 300 species. In fruits,
it attacks papaya, golden apple, pigeon pea, carambola, soursoap, cherry,
passion fruit, avocado, mango, plum, grape, citrus, bread fruit, guava
and banana.
The ornamental plants, it strikes, are hisbiscus, croton, allamanda, anthuricum,
heliconia, lantana, bougainvillaea, nerium, ixora, ficus and is equally
bad for vegetables such as tomato, pumpkin, okra, lettuce, beans, cucumber,
peppers, cabbages, squash etc.
The pink hibiscus mealy bug differs from other types due to the presence
of toxin (i.e., plant damage); pink to reddish brown in colour; no lateral
filaments; two short candle filaments; loose cotton ovisac and pink eggs.
Adults are pink in body colour but are covered with white mealy wax like
substance. The waxy filaments are short and usually obscure females. When
a large mealy bug is crushed, its body fluid is also pink. Female bug
passes through three stages i.e., egg, nymph/crawler and adult while male
passes through four stages i.e., egg, nymph/crawler, pupa and adult.
The adult female is approximately 3mm long and 1.5mm wide, oval shaped
and wingless. It has two short inconspicuous wax caudal filaments and
covered with white mealy powder, hence looks whitish in colour and is
less active than crawlers. It has an ovisac in which she lays eggs. Females
die shortly after depositing eggs.
From the sac of eggs many nymphs/crawlers emerge. The crawlers are very
active and agile, and pale in colour. In the early stage red eyes of crawlers
are conspicuous. Later on, they get covered with white powder. Newly hatched
crawlers prefer the apical and tender regions of a host plant but under
field conditions, older parts of plants may harbour large populations.
Only male nymphs/crawlers of this bug after three stages pass into pupa.
Adult males are smaller than females, have one pair of wings. Males have
two long waxy “tails”. They have non-functional mouth parts
and live only for few days.
Management of this bug is difficult due to its wide host range; easily
spread to other areas; wax coating on body; dense colonies; nature of
hiding in cracks and crevices on the bark; and crawling off the host plants.
Besides, its feeding distorts the foliage providing some protection from
pesticides.
As the body of this bug is covered with white waxy powder, it is difficult
to control them with pesticides. Certain techniques may help in giving
good results. Pesticides suppress its population to a specific level.
Trials with chemical pesticides indicate that profenofos and chorpyrifos@
1000mls/acre give satisfactory control for up to five days and a second
application should be repeated to suppress the bug’s population
at a maximum level.
Both these chemicals were sprayed using @ 125 litres per acre. The plants
were washed thoroughly (stem and leaves) as well as the soil. A delay
of spray by seven days increased the population at a maximum level. High
volume spray drops the nymphs of this pest on ground and after second
day climb up to the plant. Therefore, it is necessary that soil around
the plant is also sprayed.
The lady bug cryptolaemus montrouzieri (coccinelidae), a predator (red
head lady beetle) feeds on all stages of the mealy bug which suppresses
the high pest population. Cryptolaemus larvae are covered with a white
flocculent secretion and may be confused with pink hibiscus mealy bugs,
but are important predators and should not be destroyed.
Several effective parasitoids are known in Asia and elsewhere. One parasitoid
angyrus kamali completes a generation in less than half the time required
for its host. It suppresses pink hibiscus mealy bug population. This parasitoid
has been released on Islands in the Caribbean and appears to be providing
sustainable control. Anagyrus kamali and gyranusoidae indica parasitoids
are long-term control solution.
Following points should be noted for the control of mealy bug:
* Water should be used @125 litres per acre
for cotton and double for other crops.
* Stems should also be sprayed along with the leaves.
* Soil around the stem must be sprayed.
* Second application should be applied as soon as possible.
* Most affected plants should be uprooted and burnt.
* Land should be thoroughly prepared, so that eggs may be destroyed.
* Weeding should be done on time.
* In initial stages all the affected plants and its parts should be destroyed
by burning.
* Chloropyrephos at the rate of two litres per acre should be applied
through water.
* This pest mostly spreads in other areas of field during the picking
time, therefore, cotton pickers should be guided accordingly.
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