International Journal of Horticulture, 2016, Vol.6, No.4, 1-6
5
due to quantity and quality and stage of the prey. These results of present investigations show more or less
similarity with the observations recorded by Rao and David (1958), Mani (1986) on grapevine mealy bug and
Hanchinal (2010) on cotton mealy bug who reported average duration of male and female beetle as 52.2, 55.90
and 56.45 and 80.2, 61.40 and 62.56 days, respectively. However, the findings of Shekhar (2001) and Anil and
Jeevan (2008) reported contradictory results of 70.3, 69.7 and 77.2, 74.7 days for male and female beetle,
respectively on grapevine mealy bug, which may be due to variation in the experimental conditions.
Materials and Methods
Laboratory multiplication of mealy bug,
Maconellicoccus hirsutus
The grapevine mealy bug,
M. hirsutus
was used as prey throughout the study period. The mass production of
mealy bugs was done on medium sized ripened red pumpkin (
Cucurbita maxima
Duch.) under laboratory
conditions at 25 ±5°C temperature and 75 ±5 per cent relative humidity as suggested by Chacko et al
.
(1978) and
Singh (1978).
Mass rearing and biology of the predator,
Cryptolaemus montrouzieri
The method adopted by Chacko et al
.
(1978) and Singh (1978) was followed for rearing the predator after
sufficient development of mealy bugs on pumpkins. About 8-10 pairs of predators were released into the cage.
The beetles besides feeding on the mealy bugs, female adults laid their eggs singly or in groups among the
mealybug colonies. Full-grown grubs pupated on pumpkins or corner of the breeding cage.
The first beetle emerged within 30 days from the date of exposure of mealy bugs to the beetle, the emerging adults
were used for pre-mating, pre-oviposition, oviposition period, incubation, hatching percentage and adult longevity
studies. The beetles were provided with enough number of preys during the study period.
Studies on feeding potential of
Cryptolaemus montrouzieri
on various bio-stages of mealybugs
In order to determine the feeding potential of both the stages (grub and adult) of the predator, known number of
nymphs (2
nd
instar) and adults of mealybugs were supplied separately. For the test, newly hatched 1
st
, 2
nd
, 3
rd
and
4
th
instar grubs and emerged adults of
C. montrouzieri
were taken at the rate of ten numbers per replication with
following treatment details.
Experimental details
Stage of predator
Stage of prey
1
st
Instar
C. montrouzieri
2
nd
Instar
M. hirsutus
1
st
Instar
C. montrouzieri
3
rd
Instar
M. hirsutus
2
nd
Instar
C. montrouzieri
2
nd
Instar
M. hirsutus
2
nd
Instar
C. montrouzieri
3
rd
Instar
M. hirsutus
3
rd
Instar
C. montrouzieri
2
nd
Instar
M. hirsutus
3
rd
Instar
C. montrouzieri
3
rd
Instar
M. hirsutus
4
th
Instar
C. montrouzieri
2
nd
Instar
M. hirsutus
4
th
Instar
C. montrouzieri
3
rd
Instar
M. hirsutus
Adult male
C. montrouzieri
2
nd
Instar
M. hirsutus
Adult male
C. montrouzieri
3
rd
Instar
M. hirsutus
Adult female
C. montrouzieri
2
nd
Instar
M. hirsutus
Adult female
C. montrouzieri
3
rd
Instar
M. hirsutus
Petriplates (10 x 2 cm) were used for grubs while the adults were confined to transparent glass container (vials)
with muslin cloth. Feeding potential of male and females were studied separately.
Observations were recorded at an interval of 24 hours on number of preys consumed by the grubs and adults. It
was computed by subtracting the number of mealybugs left out from total number of insects provided. Fresh preys
were supplied daily to the grubs and adults until the grubs pupated and the adults died. The total number of
bio-stages consumed by different larval instars as well as by male and female and also the total development
period of grub and longevity of adults were recorded. The data were subjected to statistical analysis.
