This study analyzes the life table parameters of Hippodamia variegata, a lady beetle predator of Aphis gossypii, in relation to varying prey densities under laboratory conditions. Results indicate that higher prey densities reduce developmental time and increase reproductive rates in H. variegata. The findings suggest that optimal prey availability enhances the population growth and effectiveness of this biological control agent.

1. Ecological Studies 2015
1
MUHAMMA NAWAZ SHAREEF UNIVERSITY OF AGRICULTURE, MULTAN
DEPARTMENT OF AGRICULTURAL ENTOMOLOGY
RESEARCH ARTICLE
The Effect of Prey Density on Life Table Parameters of Hippomania variegata
(Coleoptera; Coccinellidae) Fed on Aphis gossypii (Homoptera: Aphididae) Under
Laboratory Conditions.
ABOUT THE AUTHORS:
Muhammad Salah-ud-Din, Ansar Abbas, Hafiz Asad Saleem, M.Naeem-ul-Qadir and M.
Zeeshan done this work and illustrate their work in documented form.
ABSTRACT:
The objectives of this study were to construct, describe and analyze life table parameters for
H.variegata population exposed to different densities of third instar of Aphis gossypii.
INTRODUCTION
Aphids are a diverse group of plant feeding insects that are predominantly found in temperate
climate zones such as North America, Europe, Central and Eastern Asia.
They cause damage directly by sucking plant sap, secrete honeydew They cause damage directly
by sucking plant sap, secrete honeydew resulting in development of sooty mold on leaves and
shoots, and indirectly as vectors of certain plant virus.
The Aphid is a pest of cotton, cucurbits and citrus and principally attack on vegetables in fields
and greenhouses. The lady beetles are most commonly known as world-wide beneficial
insects.Hippodamia variegata is an active predator used in the biological control of aphids in
cereals and oil plants in various countries. In Australia, the lady beetle was recorded preying on
12 aphid species and one psyllid specie attacking various crops, weeds and ornamental plants.

2. Ecological Studies 2015
2
MATERIALS AND METHODS
 Insect Culture
 Experimental Conditions
 Life Table Study Life Table Study
 Data Analysis
RESULT AND DISCUSSIONS:
INSECT CULTURE
Adult insects of H.variegata were collected from an alfalfa field in the Bakhtaran Province, Iran,
in June 2010, and reared on black eye bean infested with Aphis gossypii. The Aphis gossypii
nymphs were collected from a cucumber field in Rasht areas. They were reared on potted
cucumber varieties such as super dominus.
EXPERIMENTAL CONDITIONS
 Transparent plastic containers.
 Temperature 18—35 *C
 Relative Humidity 40—60 %
 Photoperiod 16:8 (L: D) h.
LIFE T ABLE STUDY
Newly emerged 1st
instar larva of H. variegata released individually in experiment and offer
densities of 20 ,40 60……. 100 so, 3rd
instar A. gossypii nymphs of black eye bean fresh leaves
to study their life table parameters. The duration of successive Developmental stages and
mortality was recorded.
DATA ANALYSIS
The life history data of all individuals of H.variegata were analyzed according to an age-stage
two-sex life table. The age-stage specific survival, age-stage specific fecundity, finite The age-
stage specific survival, age-stage specific fecundity, finite rate of increase, net reproductive rate
and mean generation time are collected accordingly .

3. Ecological Studies 2015
3

4. Ecological Studies 2015
4

5. Ecological Studies 2015
5

6. Ecological Studies 2015
6

7. Ecological Studies 2015
7
RESULTS
Developmental time of H.variegata was affected by prey density. The total developmental time
(from first instars larva to adult) decreased with increasing prey density up to 100 preys/day. The
adult pre-ovipositional period (APOP) was also significantly shorter in females fed on 100 preys
per day than those fed as larva and adults on lower prey densities.
The total pre-ovipositional period (TPOP) was longer at 20 prey/day and no noticeable change
was observed at higher prey densities. The net reproductive rate increased by increasing prey
densities /day.
DISCUSSION
Statistically significant differences were obtained in the biological and life table parameters of
H.variegata at varying densities of third instar nymphs of A.gossypii.It was revealed that at
higher prey densities, the peak reproductive value would occur at earlier ages of the female
predators. The intrinsic rate of increase, the finite rate of increase, the net The intrinsic rate of
increase, the finite rate of increase, the net reproductive rate , the gross reproductive rate also
showed some kinds of direct prey density dependence. It is obvious that higher prey densities are
more suitable than lower ones to rear this predator and increase its population.