Biology and population dynamics of solenopsis mealybug parasitoid, aenasius bambawalei hayat (Hymenoptera: Encyrtidae)
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Date
2010
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Publisher
CCSHAU
Abstract
Studies on the biology and population dynamics of Aenasius bambawalei Hayat, a parasitoid of
solenopsis mealybug, Phenacoccus solenopsis were conducted during 2009-10 in Biological Control Laboratory
as well as Research Farm of Department of Entomology, CCS Haryana Agricultural University, Hisar. Biological
studies of the parasitoid were conducted at room temperature ranging from 23.2-33.30C with 51.3-79 % R.H. and
at 20±10C, 25±10C, 30±10C and 35±10C during June, 2009 to June, 2010. Studies on the host stage preference
for the parasitoid were conducted during July, 2010 at the room temperature ranging from 26-310C with 46-73.6
% R.H. Observations on the per cent parasitization by the parasitoid, relative abundance of the hyperparasitoid
species etc were recorded under field conditions throughout the year. The results indicated that A. bambawalei
completed its development and reproduction at all the temperatures ranging from 20 to 350C. It was observed that
there was no difference in the development period between male and female of Aenasius bambawalei from
oviposition to host mummy formation. Female parasitoids took longer time to emerge out of the host mummies as
compared to males. Pre-oviposition period of less than one day was recorded while post-oviposition period was
ranging from 0-5 days at all the temperatures. There was a decrease in the oviposition period as the temperature
increased from 20±10C (35.86 days) to 35±10C (15.53 days). Daily fecundity (4.24 parasitized hosts per female)
and total fecundity (100.86 parasitized hosts per female) was maximum at the room temperature ranging from
23.2-33.30C. Males were short lived as compared to female parasitoids at all the temperatures. Sex-ratio was
always in the favour of female parasitoids at all the temperatures. Net reproductive rate (53.61), intrinsic rate
(0.185) and finite rate of increase (1.203) were maximum at the room temperature (23.2-33.30C) indicating this
temperature regime as more favourable for the development and reproduction of the parasitoid. Pre-reproductive
female hosts and third instar hosts were most preferred by the parasitoid for parasitization both under choice and
no-choice conditions. First instars were not parasitized. Maximum survival (93.49%) was observed in the
parasitoids emerged from pre-reproductive female hosts. Small sized hosts yielded more male parasitoids (91.23%)
whereas, large sized hosts yielded more female parasitoids (73.39%). Males were generally smaller in size as
compared to female parasitoids. Development of both male and female parasitoids was faster in large sized hosts
like pre-reproductive female hosts (12.0 days) and reproductive female hosts (13.53 days). The parasitoid, A.
bambawalei parasitized P. solenopsis in the field conditions throughout the year except in the months of
January-February when no colonies of the pest were seen. During crop season parasitization ranged from 13.4 to
76.6 per cent while in the off season parasitization ranged from 5.2 to 74.8 per cent on the alternate host plants. A.
bambawalei was the only primary parasitoid recorded from P. solenopsis. Four hyperparasitoids of A. bambawalei
namely, Promuscidea unfaciativentris Girault, Myiocnema comperei Ashmead, Prochiloneurus albifuniculus
(Hayat, Alam and Agarwal) and Marietta leopardina Motschulsky were recorded. Among these M. comperei was
most dominant (93.1%) during the study period while the abundance of other hyperparasitoids was quite low
ranging from 0.6-5.1 per cent. Keeping in view the potential of the parasitoid in controlling P. solenopsis, it must
be conserved on cotton and other alternate host plants.
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Keywords
Parasites, Biological interaction, Developmental stages, Animal developmental stages, Cotton, Biological phenomena, Sexual reproduction, Planting, Biological control, Livestock