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N. Geetha ¹

Affiliations
1 Division of Crop Protection, Sugarcane Breeding Institute, Coimbatore 641007, Tamil Nadu, IN

Abstract

The egg parasitioid Trichogramma chilonis is released as Trichocards during inundative releases against sugarcane borers. A study was undertaken to assess the fate of these cards in the field after their release. Results revealed that the eggs, whether they were unparasitized or freshly parasitized or those had turned black due to parasitization had failed to deter the predators, regardless of the age of the crop on which the cards were placed. In the present study, the ant species found predating on the eggs in the Corcyra cephalonica cards and Trichocards were Monomorium aberrans Forel., Camponotus compressus F., and Solenopsis geminata (F.). The predation did not vary based on the time interval allowed to lapse in the field. These findings show that the predator activity was random and that the encounter was by chance. When the cards were placed in net bags and tied to the plant, there was complete protection of the Corcyra cards and Trichocards. However, the time required for handling and tying these guarded bags for each release rendered it impractical. Hence, the Trichocards should either be released after the cards show at least 2% of the parasitoid emergence or had completed emerging just before release, to have maximum safety on the field.

Keywords

Trichogramma Chilonis, Corcyra Cephalonica, Safety, Parasitoids, Predation, Ants, Sugarcane.

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N. Geetha ¹

Affiliations
1 Division of Crop Protection, Sugarcane Breeding Institute, Coimbatore 641002, Tamil Nadu, IN

Abstract

It is well known that many trichogrammatids use volatiles from hosts or host plants during host location. When such parasitoids are reared continuously on factitious hosts in the laboratory it is believed that they may lose their ability to recognize the volatiles from their native hosts or change their host preference. Hence, this study was carried out to investigate whether Trichogramma chilonis Ishii reared on Corcyra cephalonica (Stainton) was able to recognize the volatiles of two of its native hosts in sugarcane, viz., Chilo infuscatellus Snellen and Chilo sacchariphagus indicus (Kapur). The per cent parasitoids responding to the olfactory cues, namely, the hexane-washings of eggs, scales, adult body and pheromone lures of target hosts, was assessed in nochoice and dual-choice bioassays in a "Y"-tube olfactometer. For comparison, C. cephalonica washings were used. The results indicated attraction of T. chilonis to volatiles from washings of all host sources at different levels with highest per cent parasitoids attracted to C. sacchariphagus indicus egg washings. Overlapping significant levels of attraction was found with the scale and adult body washings of fresh mated moths of all three species in no-choice tests, while C. sacchariphagus indicus was the most preferred in dual-choice tests. Volatiles from male moths were more attractive to T. chilonis than those from female moths. The parasitoids failed to respond to the body washings of >72h old moths of all the three species. Attraction of T. chilonis to the synthetic sex pheromone lures of two native hosts was observed but the parasitoid did not discriminate between them. These findings suggest that though reared on a factitious host, T. chilonis is able to recognize and respond to the native host cues and there is no change in the innate preference of the parasitoid which may have to be further confirmed with parasitism studies.

Keywords

Trichogramma chilonis, Chilo sacchariphagus indicus, Chilo infuscatellus, Corcyra cephalonica, Host Volatiles, Olfactometer.

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N. Geetha ¹, R. Balakrishnan ²

Affiliations
1 Division of Crop Protection, Coimbatore 641007, Tamil Nadu, IN
2 Section of Statistics, Sugarcane Breeding Institute, Coimbatore 641007, Tamil Nadu, IN

Abstract

The ability of the laboratory-reared egg parasitoid, Trichogramma chilonis Ishii to disperse and locate sentinel egg cards in sugarcane field was evaluated. The dispersal behaviour was monitored at different crop ages of 45 days, 3 months, 5 months, 7 months and 9 months through egg-parasitism in sentinel cards with Corcyra cephalonica (Stainton) eggs in 24 h time. The sentinel cards were placed at distances of 1, 3, 5, 7, 10, 12, 15, 20, 25 and 30 m in eight cardinal directions from the release point of the parasitoid. The effects of distance from the release point, wind direction and crop age on the host location were evaluated. Distance had a clear proportional impact on the dispersal probability but this association was complicated by the fact that distance effects changed with crop age. The dispersal of the parasitoid was found to be the highest in 45 days old crop and the lowest in 7 months old crop. The parasitoid was found to move up to 10m effectively up to 5 months of crop age which declined thereafter. Although dispersal was found up to 30m, more uniform parasitism was observed in 10m circle surrounding the release point. The direction of wind was not associated with the rate of dispersal. The influence of distance, direction and age of the crop on adult emergence was not found to vary distinctly. The inference of differential ability of the parasitoid to move in the sugarcane field in securing uniform dispersal and in fixing adequate number of release points for inundative releases are discussed.

Keywords

Trichogramma chilonis, Dispersal, Sugarcane, Crop Age, Parasitism, Emergence.

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N. Geetha ¹, Esther D. Shekinah ², P. Rakkiyappan ²

Affiliations
1 Division of Crop Protection, Sugarcane Breeding Institute, Coimbatore 641007, Tamil Nadu, IN
2 Division of Crop Production, Sugarcane Breeding Institute, Coimbatore 641007, Tamil Nadu, IN

Abstract

The egg parasitoid, Trichogramma chilonis Ishii, is widely used for the management of the internode borer (INB), Chilo sacchariphagus indicus (Kapur), in South India. However, there have been controversies regarding the dosage and frequency of releases required to attain desirable level of INB suppression. In the present study, two on-farm trials were conducted during 2008-09, comparing six releases of T. chilonis with continuous releases (from 5 months and 5½ months, respectively in trial I and II to one month prior to harvest) of T. chilonis at weekly intervals for their relative impact on INB incidence, intensity, dead hearts, number of nodes and yield, besides juice quality attributes. The cost-benefit ratio of the releases was also worked out. Continuous releases of T. chilonis were found to be better than six releases in both the trials. In the first trial, 31.1% and 56.46% reduction in the dead heart incidence was observed with six releases and continuous releases, respectively, while the yields were improved by 10.32% and 25.62%, respectively, with reference to control. In the second trial, continuous releases of T. chilonis resulted in significantly lower incidence, intensity, dead hearts and 12.15% increased yield than six releases and control, which were similar. The per cent dead hearts in control was 20.9% and 19.4% in the trial I and II, respectively. The studies also indicated the special benefits from continuous releases when the INB incidence was high. In both the trials, there was a beneficial impact on cane juice quality in terms of significantly improved % polarity and commercial cane sugar (CCS) in continuous releases in relation to control, while in the second trial percentage purity was also found to be significantly enhanced. In two separate assessments on the effect of different grades of INB infestation on the quality, there was a mixed trend in the parameters tested. The yesteryears' work and the present results on the usage of T. chilonis with reference to multiple releases for the management of borers are compared and discussed. It is recommended that in situ decisions on the frequency of releases are required because even though continuous releases are necessary to maintain the population and damage of INB low, the cost-benefit ratio tilts in favour of six releases in the present study.

Keywords

Sugarcane, Chilo sacchariphagus indicus, Trichogramma chilonis, Cost-Benefit Ratio, Dosage, Frequency, Juice Quality.

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S. Kowsalya ¹, Usha Chandrasekhar ¹, N. Geetha ¹

Affiliations
1 Avinashilingam Institute for Home Science and Higher Education for Women, Deemed University, Coimbatore - 641 043, IN

Abstract

Diabetes mellitus has been known for centuries as a chronic metoboiic disorder. Incidence of diabetes is global in distribution (1.3 per cent). The prevalence is 2 to 4 per cent in india.

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B. N. Majid ¹, K. K. K. Sampath ², H. S. Prakash ², N. Geetha ¹

Affiliations
1 Eco-Biotech Lab, Department of Studies in Biotechnology, Manasagangotri, University of Mysore, Mysore - 570006, Karnataka, IN
2 Department of Studies in Biotechnology, Manasagangotri, University of Mysore, Mysore - 570006, Karnataka, IN

Abstract

Background/Objectives: Salacia chinensis L., a high valuable anti-diabetic medicinal plant of Hippocrateaceae family, possess various medicinal properties. Its anti-inflammatory, hepatoprotective and anticancer activities originated from huge number of isolated phytochemicals such as mangiferin and salacinol. Excessive and indiscriminate collection for supplement of global demands has caused classified this plant as endangered species. Establishment of an effective regeneration system for S. chinensis via direct organogenesis as a most reliable method was the main goal of this study. Methods: The explants include leaf, node and shoot tips were inoculated on Murashige and Skoog (MS) medium fortified with different concentrations and combinations of Plant Growth Regulators (PGRs) including 6-Benzylaminopurine (BAP), Kinetin (Kin), 1-Naphthalene Acetic Acid (NAA) and Indole-3-Acetic Acid (IAA) for direct regeneration by shoot formation. Findings: The most efficient shoot regeneration in terms of the proliferation percentage (87.81 ± 3.22%), number (5.37 ± 0.02) and length of shoots (3.22 ± 0.04 cm) was obtained on MS basal medium supplemented by BAP (1.0 mg/l) and NAA (0.5 mg/l). The highest frequency in vitro ischolar_main formation (91.33 ± 2.02%) with maximum number of 4.35 ± 0.03 ischolar_mains with a length of 2.47 ± 0.03 cm was successfully achieved in half strength MS medium supplemented with 2.0 mg/l IBA. Application: The established system has this potential to be successfully employed in order to conservation and masspropagation of S. chinensis for commercial utilization.

Keywords

Antidiabetic, Auxin, Conservation, Cytokinin, Nodal Explants, Shoot Induction

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M. Kannan ¹, N. Geetha ², K. Elango ³, M. Mohan ⁴, G. Sivakumar ⁴

Affiliations
1 Nano Science and Technology, Tamil Nadu Agricultural University, Coimbatore 641 003, IN
2 ICAR-Sugarcane Breeding Institute, Coimbatore 641 007, IN
3 Imayam Institute of Agriculture and Technology, Tiruchirappalli 621 206, IN
4 ICAR-National Bureau of Agricultural Insect Resources, Hebbal, Bengaluru 560 024, IN

Abstract

A study was undertaken to characterize the granulosis viruses (GVs) of early shoot borer, Chilo infuscatellus (Snell.) (Crambidae: Lepidoptera) and internode borer, Chilo sacchariphagus indicus (Kapur) (Lepidoptera: Crambidae) in sugarcane. Scanning electron photomicrographs revealed ovo-cylindrical occlusion bodies (OBs) of GVs in early shoot and internode borers with an average size of 425.03 and 230.21 nm, 387.64 and 208.68 nm in length and breadth respectively. Transmission electron photomicrographs also showed ovo-cylindrical OBs embedded with a rod-shaped virion. The average length and breadth of the virion in the OB was 271.0 ´ 52.6 nm, 257.0 ´ 50.2 nm for early shoot and internode borer GVs respectively. Toxicity studies with the respective GVs revealed lethal concentration values of 4.38, 4.61, 6.89 OBs/mm2 and 1.85, 135.43, 8045.27 OBs/mm2 to second, third and fourth larval instars of Chilo infuscatellus granulosis virus (ChinGV) and Chilo sacchariphagus indicus granulosis virus (ChsaGV) respectively.

Keywords

Early shoot borer, granulosis viruses, internode borer, occlusion bodies, sugarcane, toxicity.

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N. Geetha ¹, R. Viswanathan ¹, T. Ramasubramanian ¹, K. P. Salin ¹, C. Yogambal ¹, P. Nirmala Devi ¹, S. Karthigeyan ², N. Chitra ³

Affiliations
1 Division of Crop Protection, ICAR-Sugarcane Breeding Institute, Coimbatore 641 007, India, IN
2 Division of Crop Improvement, ICAR-Sugarcane Breeding Institute, Coimbatore 641 007, India, IN
3 Department of Agricultural Entomology, Tamil Nadu Agricultural University, Coimbatore 641 003, India, IN

Abstract

In this study, we report Phenacoccus saccharifolii (green) on sugarcane in Tamil Nadu, India, though an earlier unre­ported isolated occurrence was observed by us in the farmers’ fields at Pugalur, Tamil Nadu. This pest has now become a major threat to sugarcane cultivation across the state as it can often kill the infested canes with or without the association of the fungal disease, pokkah boeng. Field observations revealed that the ratoon crop was affected more than the plant crop in the same locality. This species was found in large colonies, primarily between the –2 and +1 leaf of the sugarcane plant and hence, named as crown mealybug. Infestation leads to severe mottling in the leaf whorl and death of the central shoot. To the best of our knowledge, there are no earlier studies on the occurrence of this mealybug on Saccharum spontaneum L. Well-deve­loped colonies showed high activity of three encyrtid para­sitoids, viz. Aenasius phenococci (Ashmead), Aenasius arizonensis (Girault) and Leptomastix dactylopii Howard in the areas surveyed

Keywords

Encyrtid parasitoids, fungal disease, infestation, Phenacoccus saccharifolii, Saccharum spontaneum, sugar-cane.

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