TABLE CONTENTS

Potential of EPN in Management of Cotton Bollworms in Pakistan
Soomro, M.H. (1), S. Fayyaz (2) & T. Ara Khanum (2)
(1) Pakistan Science Foundation, 1, Constitution Avenue, G-5/2, Islamabad, Pakistan; (2) National
Nematological Research Centre, University of Karachi, Karachi, Pakistan.
Cotton is the most important cash crop of Pakistan and plays a vital role in the country’s
economy. Thus protecting cotton from insect pests including bollworms is of prime
importance and about 80% of the insecticides used in the country are meant for cotton.
However, the indiscriminate use of chemical pesticides has disturbed agro-ecosystem and
costs over US$195 million per year to the nation in terms of environmental and social costs.
This necessitates to search and research for eco-friendly pest management options including
the use of entomopathogenic nematodes (EPNs). In Pakistan, studies on EPN were initiated
in 1996 and so far, six species; two new and four as new records have been identified.
Pathogenicity and efficacy trials of indigenous EPN isolates have also been done with
positive results. This paper presents the results of a field trial wherein four EPN isolates viz.,
Steinernema pakistanense, S. asiaticum, S. feltiae and Heterorhabditis indica were assessed
for their infectivity against the cotton bollworm complex. EPNs cultured in Galleria
mellonella L. and stored in distilled water at 5°C were kept at room temperature for 24 hours
before use. The number of bollworms on plants before and 24 hours after EPN spray @ 1000
juveniles/100 ml water were assessed for mortality percentage of insects. All four species of
insects, viz., Helicoverpa armigera, Earias insulana, E. vitella and Pectinophora gossypiella
were found susceptible to infective juveniles of the four EPN species; S. pakistanense was the
highly virulent EPN. The intensity of infestation varied with the species and life stage of the
insects. There is a dire need to focus further research on these EPN isolates to explore and
exploit their potential as an alternative to pesticides in Pakistan, especially in IPM
programmes.
Survival Strategy of Caenorhabditis japonica Dauer Juveniles
Tanaka, R., E. Okumura, T.Yoshiga & E. Kondo
Department of Applied Biological Sciences, Saga University, Saga 840-8502, Japan
Caenorahbditis japonica forms phoretic association with the monophagous shield bug
Parastrachia japonensis showing egg-guarding and provisioning behaviors. Dauer juveniles
(DJs) of C. japonica are mainly found from the dorsum under the scutellum of adult female
bugs and are quiescent on the bug throughout a year except for the provisioning period.
During the provisioning, C. japonica leaves the bug and propagates in and around the nest of
the bug in the litter of deciduous forest. Since the provisioning period of the bug is limited to
early summer and they spend most of a year aggregating on the leaves of trees under the
reproductive diapause, C. japonica DJs seems to survive on the bugs waiting for the next
bug’s provisioning nearly for a year. To elucidate the physiological condition of DJs on the
bug, longevity and desiccation tolerance of C. japonica DJs were studied. When propagated
C. japonica DJs were kept in M9 buffer or soil at 25ºC, survival rate dramatically declined
within ten days and all DJs died in 20 days. When the propagated DJs were directly exposed
to 97% relative humidity (RH) for one week, all of them died. However, when DJs were
loaded to the shield bug in the laboratory and exposed to 97% RH, more than 60% of DJs
survived. Moreover, when the bugs collected from a mountain were exposed to 97% and 85%
RH, more than 80% of the naturally associating DJs on the bug survived. These results
5 th International Congress of Nematology, 2008 224