Browsing by Author "Sudharma, K"

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Biocontrol of mites on yard long bean (Vigna unguiculata ssp. sesquipedalis (L.) verdcourt) and chilli (Capsicum annuum L.)
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2001) Abhilash, B; Sudharma, K
Biocontrol of pests of vegetable cowpea (Vigna unguiculata sub sp. sesquipedalis (L.) verdcourt)
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 1997) Bindu , S S; Sudharma, K
Monitoring of the incidence of pests and their natural enemies was carried out in the heavily insecticide sprayed vegetable cowpea plots in farmers' fields in two locations viz. Kalliyoor and Palappur in Thiruvananthapuram District and in the unsprayed crop raised in the Instructional Farm, College of Agriculture, Vellayani, during kharif and rabi, 1996. The results of the monitoring revealed that the pea aphid, A. craccivora , the pod bugs R. pedestris and C. gibbosa and the pod borers H. armigera, L. boeticus and M. testulalis were the major pests that attacked vegetable cowpea both in the insecticide sprayed as well as in the unsprayed plots. The pea aphid was persistent in the insecticide sprayed fields where as in the unsprayed fields, they were not seen upto 35 days after sowing, in both kharif and rabi season. The pod bugs and pod borers were seen throughout the cropping period with increase in the post flowering period in both sprayed and unsprayed crop. Attack of the american serpentine leaf miner L. trifolii was observed only in the insecticide sprayed fields and was present in rabi as well as in the kharif seasons The parasitoids that were encountered were A. nigrotibiali$, Charops sp., Salius sp. and T. subvirescens and the predators were M. sexmaculatus, M. crocea, Scyanus sp., E. stali, S. geminate and X. scutellarae. The population of the natural enemies was higher during the rabi season than that during kharif season. The population of the pests and natural enemies in the insecticide sprayed and unsprayed plots were compared using students ‘t' test and the results revealed that the pest were more in the un sprayed plots but the population was higher only for a shorter period and it was effectively checked by the natural enemies, the population of which synchronized with that of the pests. There was significantly higher population of natural enemies in the unsprayed plots when compared to unsprayed plots. The role of the green lacewing C. carnea in the management of the vegetable cowpea pests was studied through replicated field trials conducted at College of Agriculture, Vellayani during 1996. The impact of biorationals viz., neem oil and tobacco decoction and insecticide, malathion on the predator C. carnea and in their effectiveness in management of cowpea pests was also studied in the field experiment. C. carnea released @ 50 per plot at fortnightly intervals effectively checked the aphid population. Among the botanicals, tobacco decoction 2 per cent was found to be effective in controlling the aphids, pod bugs and pod borers. Neem oil emulsion 10 per cent when applied at fortnightly intervals was also found to be significantly superior to the untreated control. However the infestation by aphids and the pod bugs was' less in all the treatments when compared to control. Though the control plot did not show significant reduction in yield, the quality of the produce was reduced due to the pest infestation. C. carnea @ 100 per plot at fortnightly and monthly intervals were effective against pod bugs. The pod borers were effectively checked by C. carnea • 50 arid 100 per plot. In general the monthly release of C. carnea was comparatively less effective in controlling the pests. The botanicals did not show any deleterious effect on C. carnea. When the yield was assessed in terms of weight and number of pods harvested, significantly higher yield was recorded only in plots treated with tobacco decoction 2 per cent when compared to untreated control.
Distribution and bio-ecology of phytophagous mites of vegetables,medicinal plants and ornamentals in Thiruvananthapuram district
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 1996) Sudharma, K; Madhavan Nair, G
A detailed survey on phytophagous mites and their predators associated with vegetables, medicinal plants and ornamentals was conducted for the first time in Thiruvananthapuram District, Kerala during premonsoon, monsoon seasons of 1992 and 1993. The centres selected for the survey were the college of Agriculture, Vellayani; Ayurvedic research Centre, poojappura; University Centre, Kariavattom; Tropical Botanical Garden and Reserch Institute, Palode and the District Agricultural Farm, Peringammala. The survey revealed the presence of phytophagous and predatory mites belonging to six families each. The families under the former group were Tetranychidae, tarsonemidae, Tenuipalpidae, Eriophyidae, Galumnidae and Oribatidae and under the latter group were phytoseiidae, Ascidae, Bdellidae, Cheyelitidae Cunaxidae and Stigmaeidae. Phytophagous mites belonging to the families Tetranychidae, Tenuipalpidae, and Tarsonemidae were the most widespread and the dominant species of these families were commonly found on all the three groups of plants. The survey further helped to identify eighteen new host plants of phytophagous mites which are new reports. The phytophagous mites T.cinnabarinus, T.ludeni, T.neocaledonicus , B.phoenicis,T.pacificus R. indica, P. latus and a few species under the genera tetranychus, Brevipalpus and Tarsonemous were the important species infesting vegetables, medicinal plants and ornamentals in the District. Among the acarine predators of phytophagous mites , the species belonging to the family phytoseiidae in general and in the family phytoseiidae, species of the genus Amblyseius in particular were the most widespread .The mites belonging to the family Cunaxidae and the coccinellidae, Stethorus sp . were also found to be important predators of phytophagous mites. The mean percentage of mite infested leaves and the mean population counts were also assessed to study the distribution and abundance of different groups of mites on different host plants in different seasons. The species, T.ludeni, T cinnabarinus, T neocaledonicus and P.latus on vegetables, T.ludeni and B.phoenicies on ornamentals and B.phoenicis, T.cinnabarinus, T.ludeni, T.neocaledonicus and P.latus on medicinal plants were found to be numerically dominant species capable of causing serious damage to the crops. The mean percentage of mite infested leaves and the mean population counts of phytophagous mites were the least in the monsoon season as compared to the premonsoon and postmonsoon seasons in vegetables, medicinal plants and ornamentals. The mean population counts of predators in different seasons also showed trends similar to those of phytobhagous mites, the monsoon season having the least or no predatory populations. In the postmonsoon season also their numbers were negligible. The phytoseiids were numerically the most dominant predators on vegetables, ornamentals and medicinal plants. The coccinellid predator, Stethorus and acarine predator cunaxids were also found to be important to a lesser extent. The results of replicated field trials conducted in the College of Agriculture, vellayani on selected vegetables, medicinal plants and ornamentals also revealed that, in general, the mite population was the least in the monsoon season as compared to the premonsoon and postmonsoon season. In general, the population development was found to be positively correlated with maximum temperature and relative humidity. The nature and symptoms of damage of T.cinnabarinus on Adhatoda ;T.ludeni and T.neocaledonicus on rosea; T.pacificus on Dendrobium; R.indica on T.alata; B.phoenicis on the medicinal plants G.sylestre,S.ciliates O.sanctum, and on Caladium, Maranta and Dendrobium and P.latus on chilli, bittergourd , ridegorud and T. erecta were studied and described in detail. The biology and biometrics of T. cinnabarinus, T.ludeni, T neocaledonicus, T.pacificus and B.phoenicis were studied on selected host plants and described in detail. Crop loss studies conducted on bhindi and chilli by releasing different population levels of T.ludeni and P.latus revealed that , the stage of the crop at which infestation commenced was an important factor which determind the crop loss. It was also found that there was crop to crop variation on the levels of tolerance to different mite loads. No significant difference was noticed in the distribution of T.ludeni on the top, middle and bottom strata of bhindi plants while in chillies the mite P.latus preferred the top stratum indicating a preference for young growing tissues for feeding and oviposition.
Entomopathogenic fungi for the management of insect pests in rice ecosystem
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2015) Malini Nilamudeen; Sudharma, K
Evaluation of entomopathogenic fungi against pest complex of chilli (Capsicum annuum L.)
(Department of agricultural entomology, College of agriculture, Vellayani, 2014) Lokesh, S; Sudharma, K
An investigation entitled “Evaluation of entomopathogenic fungi against pest complex of chilli (Capsicum annuum L.)” was carried out during 2012-14 at College of Agriculture, Vellayani. The objectives were to evaluate the efficacy of Beauveria bassiana (Balsamo) Vuillemin, Lecanicillium lecanii Zare & Gams and Metarhizium anisopliae (Metschnikoff) Sorokin against pests of chilli, assess the compatibility of the fungi with pesticides and develop products of the fungi. Three fungi viz. Fusarium solani (Mart.) Sacc and Penicillium oxalicum Currie and Thom infecting Aphis gossypii Glover and Isaria javanica (Friederichs & Bally) Brown & Smith infecting Bemisia tabaci Gennadius were isolated and the reports on these insects are new in India. An yeast, Meyerozyma caribbica (Vaughan-Martini, Kurtzman, S.A. Meyer & E.B. O'Neill) Kurtzman & M. Suzuki infecting B. tabaci has been isolated and the report of the yeast is new. The pathogenicity of fungal isolates was evaluated against A. gossypii, B. tabaci, P. latus and S. dorsalis. All the treated insects showed symptoms of infection by all the isolates except Llm. The virulence of the fungi was evaluated @ 108 spores ml-1. At 48 hours after treatment, the highest mortality of 99.97 per cent to A. gossypii was caused by L. lecanii (Ll8). I. javanica caused the maximum mortality of 83.61 per cent to B. tabaci. With respect to P. latus, the highest mortality of 80.65 per cent was recorded in B. bassiana (Bb5a) and it was on par with the mortality in L. lecanii (Ll8) and B. bassiana (Bb21). The effect of all the fungi except L. lecanii (Llm) to S. dorsalis was on par. The LC50, LC90 and LT50 values of the fungal pathogens to A. gossypii, B. tabaci, P. latus and S. dorsalis were worked out. To achieve control of these sucking pests in the shortest period, the field doses fixed for B. bassiana (Bb5a), B. bassiana (Bb21), L. lecanii (Ll8) and M. anisopliae (Ma4) ranged from 1.68 × 108 to 5.10× 109, 1.68× 108 to 5.75× 109, 2.76× 108 to 4.12× 109 and 3.11× 108 to 3.12× 109 spore ml-1 respectively. Talc based products of the fungi were prepared and their shelf life was determined. The cfu observed at 60 days after storage was 1.03× 108 ml-1, 0.44× 108 ml-1, 0.68× 108 ml-1 and 1.18× 108 ml-1 for B. bassiana (Bb5a), M. anisopliae (Ma4), L. lecanii (Ll8) and Bb21 respectively. The compatibility of the fungal pathogens with pesticides was assessed. Dimethoate (0.06%) was the most inhibitory to all the fungal isolates. M. anisopliae (Ma4) was least inhibited by the pesticides. Field experiment was conducted to evaluate the fungal pathogens and newer molecules of insecticides against pests of chilli. The treatments B. bassiana (Bb5a) and L. lecanii (Ll8) @ 20 g l-1 and acetamiprid (0.004%) were found to be on par in reducing the P. latus population. B. bassiana (Bb5a) 20 g l-1 was found on par with acetamiprid (0.004%), spiromesifen (0.02%) and emamectin benzoate (0.002%) in their effectiveness to S. dorsalis at 7 DAT. The fungal isolates did not affect the spider population. The benefit cost ratio was highest for the treatment with B. bassiana (Bb5a) 20 g l-1 (2.62). To conclude, the fungal pathogens viz. B. bassiana (Bb5a and Bb21), L. lecanii (Ll8) and M. anisopliae (Ma4) @ 20 g l-1 are safe, economical and ideal for integration with newer pesticide molecules viz. emamectin benzoate (0.002%), spiromesifen (0.02%) and acetamiprid (0.004%) for management of pest complex of chilli.
Evaluation of entomopathogenic fungi for the management of coleopteran pests and characterisation of pesticide tolerant strains
(Department of agricultural entomology, College of agriculture, Vellayani, 2014) Anis Joseph, R; Sudharma, K
Pathogenicity of indigenous entomopathogenic fungi against select lepidopteran pests
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2016) Praveena, A; Sudharma, K
The present study entitled “Pathogenicity of indigenous entomopathogenic fungi against select lepidopteran pests” was carried out in the Department of Agricultural Entomology, College of Agriculture, Vellayani during 2014-2016 with the objective to identify indigenous entomopathogenic fungi and evaluate their pathogenicity to lepidopteran pests of banana and vegetables. Survey was conducted in five agroecological zones of Thiruvananthapuram district at bimonthly intervals during 2015-16, for the isolation of fungi. Fungi from mycosed cadavers and 900 soil samples, collected from cultivated and uncultivated fields were isolated. Of the ten isolates of fungi selected from the 115 fungal isolates obtained, three were from mycosed cadavers which consisted of two isolates of Beauveria bassiana (Balsamo) Vuillemin (SP2 and SP4) and one isolate of Fusarium oxysporum Schlecht (SP1). Of the seven isolates from soil, one isolate was Fusarium solani (Mart.) Sacc. (SP6), five were isolates of Metarhizium anisopliae Metschnikoff (Sorokin) and one isolate was Purpureocillium lilacinum Thorn (Samson). Four isolates of M. anisopliae were trapped using larvae of Galleria melonella L. and one was trapped using grubs of Odoiporous longicollis Olivier. The isolate, S10 was obtained through soil plate method, with selective media. Symptoms of fungal infection varied, which was mainly reflected in the mycelial colour and growth of the isolates. Morphological and cultural characteristics also varied among the fungal isolates. Further, molecular characterization of the fungi was done through ITS sequencing. GenBank accession numbers for all the ten isolates were obtained on submission of nucleotide sequence in National Center for Biotechnology Information (NCBI). Among the various indigenous isolates, highest spore count was recorded in the M. anisopliae isolate, SP11 (28.01 x 107 spores mL-1) at 14 days after inoculation. The pathogenicity of the ten indigenous isolates and two isolates from National Bureau of Agricultural Insect Resources (NBAIR) were evaluated against five lepidopteran insects infesting banana and vegetables at different concentrations. The isolate M. anisopliae (SP8) recorded the highest mortality of 83.33 to 100 per cent and 64.44 to 95.83 per cent against the second instar larvae of Diaphania indica Saunders and first instar larvae of Leucinodes orbonalis Guenee at 107 to 109 spores mL-1 at seven days and five days after treatment respectively. The isolates SP11 and Ma4 of M. anisopliae that caused mortality of 83.33 to 100 per cent and 63.33 to 100 per cent were the most effective isolates against second instar larvae of Sylepta derogata Fabricius and Hymenia recurvalis Fabricius respectively. All the isolates except M. anisopliae (SP11) and B. bassiana (Bb5a) were non pathogenic to the larvae of Spodoptera litura Fabricius. The colour of the mycelial growth varied with isolates. A pot culture experiment was conducted in the Instructional Farm, Vellayani during April to June 2016, for the evaluation of seven indigenous isolates and two NBAIR isolates against leaf webbers in amaranthus, variety Arun. The lowest number of plants infested by webbers, webbings plant-1 and larvae web-1 at 14 days after treatment and the highest yield was recorded in the isolate M. anisopliae (SP11) @ 108 spores mL-1 and it was followed by M. anisopliae Ma4 and SP8 . To conclude, ten indigenous isolates of entomopathogenic fungi were collected from mycosed cadavers and soil and were identified as B. bassiana (SP2, SP4), F. oxysporum (SP1), F. solani (SP6), M. anisopliae (SP7, SP8, SP9, SP11 and SP13) and P. lilacinum (S10) through morphological, cultural characters and molecular characterization. Pathogenicity test to five lepidopteran pests showed that M. anisopliae (SP7, SP8, SP9, SP11, SP13) and NBAIR isolates of B. bassiana (Bb5a) and M. anisopliae (Ma4) were pathogenic to D. indica, H. recurvalis, L. orbonalis and S. derogata. Results of pot culture experiment showed that the indigenous isolates M. anisopliae (SP11) and (SP8) and NBAIR isolate M. anisopliae (Ma4) can be exploited for the management of leaf webbers in amaranthus.