Efficacy of Entomopathogenic Fungus Fusarium pallidoroseum (Cooke) Sacc. Against Gypsy Moth (Lymantria obfuscata Walker)
Barkat Hussain ,
G.N. Malik ,
Fusarium pallidoroseum isolated locally from cadaver of Lymantria obfuscata was evaluated as bio-control agent against caterpillars of same pest at concentrations of 1x1010, 1x109, 1x108, 1x107, 1x106, 1x105, 1x104, 1x103, 1x102 and 1x101 spores mL-1. No mortality was observed up to 3rd day of inoculation. 1x1010 spores mL-1 was the most promising concentration as it inflicted an initial mortality of 43% on the 4th day and cent percent mortality on the 9th day. The LC50 values ranged from 1.969x103 (16th day) to 1.256x1011 (4th day). A linear positive association was observed between mortality and days of observation.
The gypsy moth, Lymantria dispar (L.), is a highly destructive forest pest with a wide host range (Liebhold et al., 1995). Evidence indicates that infestation area and host range of Lymantria obfuscata Walker has increased tremendously in Kashmir Valley of Jammu and Kashmir State, posing a serious threat to horticulture industry (Masoodi et al., 1990). The pest has also emerged as serious defoliator of some other economically important trees like poplar (Populus deltoides) and Willows (Salix purpurca). Use of sex pheromone traps in controlling this leaf defoliator has been reported by Beroze et al. (1973), Punjabi et al. (1974) and Masoodi et al. (1990). However, use of persistent pesticides is still the only reliable and practical option to control this pest. There is a renewed interest in the adoption of alternative management strategies for this pest, as the deleterious effects of pesticides are well known now. Biological control is one of the promising methods of pest control and constitutes an eco-friendly alternative strategy. Among entomopathogens, fungi are important, as they are virulent, infect insect by contact, persist in the environment for a long time and have one of the largest host list. The present study was, therefore, undertaken to explore the possibility and effectiveness of Fusarium pallidoroseum (isolated locally from dead caterpillars) as a biocontrol agent against gypsy moth (Lymantria obfuscata).
MATERIALS AND METHODS
The present studies were carried at Division of Plant Pathology, (Sher-e-Kashmir
University of Agricultural Sciences and Technology of Kashmir) Shalimar campus
during spring (April-May) seasons of 2004-2006. The test fungus (Fusarium
pallidoroseum) was isolated from dead caterpillars of Lymantria obfuscata
collected during heavy infestation of Populus deltoids by this pest
at Sanatnagar Srinagar Kashmir. The fungus was cultured on Richards agar medium
and test spore concentrations (1x1010, 1x109, 1x108,
1x107, 1x106, 1x105, 1x104, 1x103,
1xx102 and 1x101) were prepared in double distilled sterilized
water with the help of haemocytometer. The freshly hatched healthy populations
of pest were collected from infested poplar plantation, mixed together and reared
on host leaves. The caterpillars were used after 2nd week of collection for
evaluation against test fungus. For each treatment three replications were run
and each replication was consisting of 100 caterpillars. Caterpillars of each
replicate was inoculated by spraying with 30 mL spore suspension of test concentration.
The control was run to rule out any natural infection. Mortality was recorded
after every twenty four hours.
For working mortality percentage, mortalities were converted to correct per cent mortalities for control by Abbotts (1925) formulae. The data thus obtained were subjected to probit regression analysis by the method of Finney (1952) and LC50 values were worked out.
RESULTS AND DISCUSSION
The results (Table 1) indicated that there was a linear association
between probit mortality and log concentration (spores mL-1). Chi-square
of each test day indicated good fit of points about the lines at 0.05% level
of significance. The LC 50 ranged from 1.969x103 (16th day) to 1.256x1011
(4th day). A perusal of Table 2 indicated that Fusarium
pallidoroseum inflicted an initial mortality of 43% at the highest concentration
of 1x1010 spores mL-1 on the fourth day. This was closely
followed by next highest concentration (1x109 spores mL-1)
with a mortality of 40%. The lowest concentration (1x101 spores mL-1)
was effective in causing mortality of 7% on 6th day. Cent percent mortality
at the highest concentration (1x1010 spores mL-1) was
recorded on 9th day followed by 1x109 spores mL-1 and
1x108 spores mL-1 which inflicted cent per cent mortality
on 12th and 13th day, respectively.
response of Fusarium pallidoroseum against Lymantria obfuscata
Indicate heterogencity at p = 0.05, **: Fiducial limit at 0.95 confidence
per cent mortality of Lymantria obfuscata at different days at
Comparatively medium concentrations of 1x107 and 1x106
spores mL-1 were also effective in complete annihilation of target
organism on 15th day. In general an increasing trend in mortality was observed
with advancement of time with most concentrations, which indicated that there
was a linear positive association between mortality and days of observation.
An increase in mortality with increase in doze of inoculum in the present study
is in conformity with findings of Mohi-ud-din et al. (2007) in case of
Beauveria bassiana against white grub (Holotricha sp.). Gupta
et al. (1991) also isolated beauvertcin as an insect toxin from Fusarium
semitectum (Syn. F. pallidoroseum) and reported that ethylene chloride
soluble extract from the mycelium of F. pallidoroseum showed toxicity
against Colorado potato beetle (Leptinotarsa decemlineata coleopteran)
in a foliar spray assay. It is cytotoxic as reported by Grove and pople (1980)
and possess some insecticidal properties against mosquito larvae and blowfly.
The first reported isolation of beauvercin from the genus Fusarium,
F. monoliforme which is known to produce the mycotoxins fumonisins, monoliformin
(Wiebe and Bjeldanes, 1981) fusarin (Cole et al., 1973). The present
study indicated the effectiveness of entomopathogenic fungus, F. pallidoroseum
as a bio control agent against gypsy moth (Lymantria obfuscata) as
it inflicted initial mortality of 43% on the 4th day and lead to complete annihilation
of target pest on the 9th day of application at a concentration of 1x1010
spores mL-1. Strategies for the use of entomopathogenic organisms
for insect control are basically the same as that for other biological control
agents. They may be used to augment naturally occurring pathogens (augmentation),
conserved or activated in nature (conservation), introduced into pest populations
as classical biological control agents to become established and exert long-term
regulation of the pest or are used for rapid short-term control.
Abbott, W.S., 1925. A technique for computing effectiveness of an insecticide. J. Econ. Entomol., 18: 265-267.
Beroza, M., A.A. Punjabi and B.A. Bierl, 1973. Disparlure and analogues as attractants for Lymantria obfuscata. J. Econ. Entomol., 66: 12-15.
Cole, R.J., J.W. Krisky, H.G. Cutler, B.L. Doupnik and J.C. Peckham, 1973. Toxins from F. monoliforme: Effects on plants and animals. Science, 179: 1324-1326.
Finney, D.J., 1952. Probit Analysis. 1st Edn., Cambridge University Press, UK.
Grove, J.F. and M. Pople, 1980. The insecticidal activity of beauvericin and the enniatin complex. Mycopathologia, 70: 103-105.
CrossRef | Direct Link |
Gupta, S., S.B. Krasnoff, L. Renwick Nancy, Underwood, J.A.A. Renwick and R.W. Roberts, 1991. Isolation of beavercin us an insect toxin from Fusarium Semitectum and Fusarium moniliforme var. Sabglutians. Mycopathologia, 115: 185-189.
Liebhold, A.M., K.W. Gottschalk, R.M. Muzika, M.E. Montgomery, R. Young, K. O'Day and B. Kelley, 1995. Suitability of North American tree species to the gypsy moth: A summary of Þeld and laboratory test. Gen. Tech. United Stats Department of Agriculture and Forist Services, Washington DC.
Masoodi, M.A., R.A. Trali and A.M. Bhat, 1990. Suppression of Lymantria obfuscata Walker by sex pheromone trapping of males. Indian J. Entomol., 52: 414-417.
Mohi-ud-din, S., F.A. Zaki, N.A. Munshi, Arif Jan and R.A. Wani, 2007. Comparative susceptibility of different grub stages to local strain of Beauveria bassiana. J. Entomol., 4: 56-59.
CrossRef | Direct Link |
Punjabi, A.A., M. Beroza and B.A. Biere, 1974. Trapping of Lymantria obfuscata Walker with disparlure. Indian J. Entomol., 36: 125-127.
Wiebe, L.A. and L.F. Bjeldanes, 1981. Fusarin C, A mutagen from Fusarium moniliforme grown on corn. J. Food Sci., 46: 1426-1636.
CrossRef | Direct Link |