Informatics Publishing Limited

Y. G. Prasad ¹, M. Prabhakar ¹, G. Sreedevi ¹

Affiliations
1 Central Research Institute for Dryland Agriculture, Santoshnagar, Hyderabad, 500059, Andhra Pradesh, IN

Abstract

The mealybug, Phenacoccus solenopsis Tinsley, a polyphagous pest with a wide host range is of recent occurrence on Bt cotton in all the three major cotton growing zones in India. The first perceptible appearance of the pest on cotton in Warangal district of Andhra Pradesh was noticed in Kharif 2008. P. solenopsis was recorded on several plants other than cotton which include cultivated crops and weed hosts. The mealybug population is naturally regulated by Aenasius bambawalei Hayat (Hymenoptera: Encyrtidae). This paper reports the dynamics of this key parasitoid in a spatio-temporal perspective. Monitoring of the parasitoid on P. solenopsis occurring on weed hosts found on field bunds, crop fallows, barren lands, roadsides and village backyards indicated its activity on eight weed hosts late in the cotton growing season of 2009. During the year 2010, its activity started early in the season on few weed hosts while many more supported parasitization late in the season. Parasitoid activity was higher (11.3 to 15.3%) initially on the key hosts (Corchorus olitorius L., Abutilon indicum L., and Sida acuta Burm. F.) early in the season (August) which later shifted gradually to the main host (cotton) during the later part of the season. Cropping system and spatial perspective indicated that cotton fields adjacent to roadside and crop fallows supported higher parasitization during September (8.3 - 9.1%) and cotton fields adjacent to barren lands in December (13.3%). These findings have implications for the management of P. solenopsis mealybug on cotton from an agro eco-system perspective.

Keywords

Phenacoccus solenopsis, Aenasius bambawalei, Gossypium hirsutum, Cotton, Mealybug, Parasitoid, Alternate Hosts, Weed Flora, Cropping Systems, Diversity.

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M. Prabhakar ¹, Y. G. Prasad ¹, B. Venkateswarlu ¹

Affiliations
1 Central Research Institute for Dryland Agriculture, Santoshnagar, Hyderabad 500 059, Andhra Pradesh, IN

Abstract

Natural parasitism of the red hairy caterpillar, Amsacta albistriga (Walker) by a mermithid nematode, Hexamermis dactylocercus Poinar Jr. and Linares is reported for the first time. Higher parasitisation by H. dactylocercus was recorded during epidemic outbreak of A. albistriga during 2007 (28.5%) and in 2008 (6.5%) when the pest incidence was relatively lower due to late onset of monsoon. The mermithid activity was associated with high rainfall in both the years. Seasonal dynamics of H. dactylocercus is discussed.

Keywords

Nematode, Mermithid, Hexamermis dactylocercus, Red Hairy Caterpillar, Amsacta albistriga.

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P. S. Vimala Devi ¹, Y. G. Prasad ¹, A. Chowdary ¹

Affiliations
1 Directorate of Oilseeds Research (ICAR), Rajendranagar, Hyderabad 500 030, Andhra Pradesh, IN

Abstract

Drying Nomuraea rileyi conidia along with the solid substrate in an air stream gave a virulent product that gave high mortality of Spodoptera litura larvae in a laboratory bioassay whereas drying over silica gel or calcium chloride resulted in loss of efficacy. Bioassays with oil formulations of spores dried in an air stream resulted in comparable mortality of third instar S. litura (Fabr.) larvae with that of unformulated conidia. The oil formulation with Triton-X-100 caused significant reduction of S. litura populations feeding on groundnut and castor in field experiments. Natural parasitisation levels of two larval parasitoids on S. litura were similar in the fungus treatments and untreated controls.

Keywords

Castor, Drying, Field-Tests, Formulation, Groundnut, Nomuraea rileyi, Spodoptera litura.

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P. S. Vimala Devi ¹, Y. G. Prasad ¹, B. Rajeswari ¹

Affiliations
1 Directorate of Oil Seeds Research, Rajendranagar, Hyderabad 500 030, IN

Abstract

Bacillus thuringiensis var. kurstaki was as effective as monocrotophos (0.05%) in causing feeding cessation and mortality of Achaea janata (Linnaeus) on castor. However, it was ineffective against Spodoptera litura (Fabricius) larvae. Neem seed kernel extract (2%) resulted in ovipositional deterrence to S. litura.

Keywords

Achaea janata, Bacillus thuringiensis, Castor, Neem, Spodoptera litura.

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S. Manickvasagam ¹, N. Ramakrishanan ¹, S. Anuradha ¹, Y. G. Prasad ¹

Affiliations
1 Division of Entomology, Indian Agricultural Research Institute, New Delhi - 110 012, IN

Abstract

Biophysical and biochemical properties of the baculoviruses (BV) have been extensively used to identify as well as to differentiate the subgroups of BV, the viruses within the subgroup and the variants of same virus species (Harrap and Payne, 1979). Nucleic acid analysis through electron microscopy, sedimentation techniques, reassociation kinetics and restriction endonuclease (REN) analysis are the tools generally employed. Of these, REN analysis is relatively a simple and well defined method for the accurate classification of more than 300 BV recorded from various insect hosts. This analysis relies on a selected enzyme cleaving the viral DNA at a specific nucleotide sequence to produce defined DNA fragments. Identification and subsequent grouping of genotypically similar BV will help in eliminating some of the confusion arising from classification based on host origin (Gettig and McCarthy, 1982). In the present study, the nuclear polyhedrosis viruses of Amsacta albistriga (AaNPV), Spodoptera litura (SINPV) and Spilosoma obliqua (SoNPV) which have great potential in the microbial control of the respective host pest species (Jayaraj et al., 1977; Ramakrishnan et al., 1981; Battu and Ramakrishnan, 1989) were compared through REN analysis.

Keywords

Baculoviruses, Nuclear, Polyhedrosis Viruses, Amsacta albistriga, Spodoptera litura, Spilosoma obliqua, Endonuclease Restriction Analysis.

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