Browsing by Author "Ranjith, A M"

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Bionomics and ecological management of coconut eriophyid mite
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2001) Vidya, C V; Ranjith, A M
Coconut perianth mite Aceria (Eriophyes ) guerreronis (Kiefer) and its management
(Kerala Agriculture University, 2000) L, Nadarajan; Ranjith, A M; Thomas, Jim
Distribution of coconut lacewing bug Stephanitis typicus distant and its natural enemy complex and assessment of biocontrol potential of the major natural enemies
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1994) Unnimon, N K; Ranjith, A M
etc. A study on the distribution of the coconut lacewing bug Stephanitis typicus and its natural enemy complex was carried out during the period 1991-92 at four selected root (wilt) prone districts of kerala . The bio-control potential of the major identified natural enemies were also carried out during the same period . The results revealed that population of S.typicus showed a fluctuation throughout the year . The population was higher in the field during the dry seasons and it was at lower levels in rainy periods. The numbers of the pests increased from January onwards and recorded its maximum in March-April. The population started decreasing from May onwards and recorded the lowest level in June-July . From August the number of pest again started increasing and reached the second maximum in September - October. The level of population recorded was lowest in November- December. Congregation of S. typicus was observed in higher numbers on the inner whorls of coconut crown. Compared to leaves of inner whorls, the number of pest were fewer in middle and outer whorls. Natural enemy population was observed to remain stagnant throughout the year. Only a slight fluctuation was recorded in population of natural enemies , in accordance with the increased level of pest population . Generally a low level of natural enemy population was observed in the field throughout the study period . Rearing of S. typicus in glasshouse condition on different host plants like coconut , turmeric and arrowroot showed the preference by the pest to the coconut plants. Compared to other host plants the multiplication and survival of the pest was more on coconut plants. Among the natural enemies observed in the field , the mired predator S. praefectus was recorded as the important one . other natural enemies observed in the field included spiders and one pentatomid bug. It was noticed that the mired predator consumed both adults and nymphs of the pest . But in case of spiders they preferred adults of the pest to nymphs.
Enhancing the performance of the egg parasitoid, Trichogramma.chilonis Ishii (Trichogrammatidae : Hymenoptera)
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2006) Shajna, P K; Ranjith, A M
A study entitled ‘Enhancing the effectiveness of the egg parasitoid Trichogrmma chilonis Ishii (Trichogrammatidae: Hymenoptera)’ was carried out at the College of Horticulture, Vellanikkara with the objectives of increasing the effectiveness of T. chilonis and to standardize the optimum storage period of the trichocards. A prototype of an olfactometer suitable to monitor the movements of T. chilonis was at first made using polyester film for standardizing the design. The prototype was validated by keeping the kairomones in each of the four arms. As this was found to be a success, it was further fabricated in transparent acrylic sheet incorporating slight modifications. Various error factors were identified during the continued studies and they were eliminated and an improved design was standardized as uniform air inflow olfactometer. The responses of T. chilonis to different semiochemicals were studied in the uniform air inflow olfactometer. A higher response of adult parasitoids was noticed towards moth extracts of C. medinalis and Corcyra cephalonica and also moth scale extract of C. cephalonica in hexane solvent. This may be because hexane could extract more concentration or wider range of the kairomones which attract the parasitoids. The results corresponding to the response to plant volatiles emanating from the weeds in the paddy ecosystem are a clear pointer to the ecological adaptation of T. chilonis for survival. The highest attraction was towards the leaf folder damaged leaves followed by plant parts of Oryza rufipogon. Among the different semiochemicals, significant attraction was towards 10 per cent honey solution. The results thus established that a band or grid application of honey solution will increase the longevity of adults as well as the per cent parasitism. The adult moth which is the primary producer of eggs is the most preferred from among the different life stages of C. medinalis tried. A wind tunnel set up was fabricated to evaluate the olfactory responses of T. chilonis to the best semiochemicals. The distance travelled by the parasitoids was observed for every 30 minutes, for a total duration of three hours. Maximum distance travelled by the adult parasitoids was towards honey solution. The results validate the findings observed using the four arm olfactometer (free choice test) with a single source wind tunnel (no choice test). The effect of refrigerated storage on the emergence and parasitization efficiency of T. chilonis was studied. More than 50 per cent emergence was noticed up to 36 days in four day old cards which is of interest to nucleus stock of Trichogramma being maintained at the laboratories. The results of the study have shown that the Trichogramma emergence can be delayed even up to 50 days under ordinary refrigerated storage. Such cards even with around 10 per cent efficiency would be more economical than continuous rearing of Corcyra culture and production of trichogrammatids. Even for farmer situations, it may be more advisable to manage initial leaf folder populations at its first level of emergence itself. At this time the population is very low and even a 10 per cent parasitoid emergence can easily take care of first generation of leaf folder.
Evaluation of multi x bi bivoltine hybrids of silkworm
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1998) Rajeni Narayanan; Ranjith, A M
In a study undertaken to evaluate the region and season specific multi x bi and bivoltine hybrids of silkworm Bombyx mori, for commercial exploitation in Kerala, six hybrids of silkworm were reared using K-2 and S-36 mulberry varieties under Vellanikkara condition. The crosses used were PM x NB18, PM X NB4D2 and their reciprocals, NB4D2 x NB18 and its reciprocal and PM as check. The evaluation was carried out based on characters like leaf consumption, larval duration and weight, cocoon and shell weights, shell ratio percentage, average filament length, denier, reelability and renditta. The climatic factors were also correlated with major economic characters of silkworm. The present study confirms the superiority of bivoItine silkworm hybrids like NB4D2 x NBI8 and NB18 x NB4D2 justifying their wide acceptance in states other than Kerala. It is evident that if rearing is done in a systematic way, by strictly adhering to the brushing period in correlation with the seasons and if the use of high quality mulberry varieties is advocated these crosses will yield good returns in Veil ani kkara. Though the various economic parameters reflected a variable trend, ultimately when the average filament length/g cocoon, shell ratio percentage and cocoon weight were considered, the bivoltine hybrids performed superior to the others.
Identification and management of horticultural pests
(New India publishing Agency,NewDelhi, 2015) Ranjith, A M
Influence of food plants on the consumption of folfage and pupal characters of Pericallia Ricini Fab. (Arctiidae: Lepidoptera)
(Kerala Agricultural University, 1985) Ranjith, A M; Dale, D
The influence of different food plants on the growth of the arctiid caterpillar Pericallia ricini is discussed. DJe to differences in the quality of the nutrients and the nutrient balance in the different food plants, the pupal periods of caterpillars feeding on the varied food plants differed significantly. The pupal weights and the mortality of larvae and pupae differed batween the insects feeding on the different food plants. An increased consumption of food by larvae of the later instars and by females than males was also observed.
Insect pollinators of oil palm in Kerala
(Department of Agriculture, College of Horticulture, Vellanikkara, 2010) Sambath Kumar; Ranjith, A M
Integrated insect pest management (IIPM) and biological control based integrated pest management (BIPM) in rice
(Department of Agricultural Entomology, College of Horticulture,Vellanikkara, 2012) Pramod Kumar; Ranjith, A M
Management of banana pseudostem weevil Odoiporus longicollis Olivier (Coleoptera: Curculionidae) with induced resistance and epideictic compounds
(Department of Entomology, College of Horticulture, Vellanikkara, 2002) Raihana, K C; Ranjith, A M
Natural enemy complex of coconut lacewing bug Stephanitis typicus distant and predatory potential of major natural enemies
(Kerala Agricultural University, 1998) Unnimon, N K; Ranjith, A M
Resistance mechanisms against the Pseudostem Weevil Odoiporus longicollis Olivier (Coleoptera : Curculionidae) in banana
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1999) Lalitha, N; Ranjith, A M
Studies on the consumption, digestion and utilisation of food plants by Pericallia ricini
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1981) Ranjith, A M; Dale, D
The present investigation was carried out in the Entomology Department of the College of Horticulture, Vellanikkara. It was aimed at working out idices relating to consumption, digestion and utilisation of eight food plants by the larvae of Pericallia ricini F., a polyphagous pest in Kerala. The study was also meant to assess the relative growth of the caterpillars on the different food plants so that a general idea can be obtained on the suitability of the food plants to the larvae. Data on the pupal and adult emergence were also collected with a view to probing further in to the identification of probable insect growth inhibitory substances among the host plants. The most preferred plants with regard to the consumption of foliage were pumpkin, castor and brinjal. Consumption index was calculated on fresh and dry weight bases. It was seen that the consumption of brinjal leaves was the maximum and the index was the least for sweet potato. The other foods did not differ among them significantly. On dry weight basis, banana-fed insects with a C.I. of 3.02 ranked first, followed by larvae fed on cotton. Larval weight gain on brinjal was the maximum followed by those grown on pumpkin. The least weight gain of 0.66 g was exhibited by larvae which were fed on banana leaves. The last instar larvae consumed the largest quantity of food during their larval period. Consumption of food was very low among the third instar larvae. Females were to consume more foliage than the corresponding male counterparts. The differences in consumption by the two sexes were statistically significant. The growth rates were calculated both on fresh and dry weight basis. On fresh weight basis, larvae reared on brinjal had the highest growth rate of 65.7 and the least growth rate of 30.7 was obtained from larvae grown on banana. On dry weight basis, it was seen that pumpkin was superior to all others in supporting larval growth of P. ricini. The approximate digestibility was calculated on the basis of fresh weight of the digestible food and the weight of the ingested food. A.D. was the maximum (91.40 per cent) with sesamum on fresh weight basis, but on dry weight basis, it was castor that the larvae digested most. Indices relating to efficiencies of converting ingested food and digested food to biomass were also calculated both on fresh and dry weight bases. The reasons for the observed values deviating from the expected ones are discussed. Utilisation of nitrogen, both ingested and digested, by the larvae varied among food plants significantly. Colocasia, sesamum and cotton had the higher values of E.C.I. (N). In the descending order. But taking into consideration of the E.C.D. (N) values, the numerical figure was the highest with castor and the least with banana. The present study has clearly indicated that the food plants have a significant effect on the pupal period, pupal weight and pupal length. It is also seen that some host plants cause larval and pupal mortalities at varying degrees. The effect of larval feeding on the sex ratio of emerging adults was also recorded. Insects fed on castor and cotton leaves showed the near best sex ratio of 1: 0.88. In the case of sweet potato and sesamum, the ratio was 1: 2. All other foods led to sex ratios ranging from 1:0.67 to 1: 2.
Synergistic interaction of biocides and insecticides on tomato fruit borer helicoverpa armigera (Hubner)
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2004) Lily Levin; Ranjith, A M
The tomato fruit borer Helicoverpa armigera (Hubner) is a serious pest of several cultivated crops and has attained global importance. H. armigera displays formidable biological profiles based on multihost feeding, strong flying ability and genetic versatility, and consequently it resists any synthetic insecticide used to control it world wide. This pest is out of control precisely because of overuse of synthetic insecticides, which has led to development of resistance and destruction of natural enemy complex. Hence the present study was carried out to investigate the efficacy and interaction of different plant extracts, microbial pesticides and synthetic chemicals, alone and in combination against H. armigera to reduce the cost, to avoid the after effects of commonly used insecticides and to consider its fitness in different management options. The population of H. armigera was found to be more during October to March period. There was no incidence of pest from July to September period. Among the four ecosystems, tomato recorded the highest number of larvae followed by bhendi, bittergourd and cowpea. The species of natural enemies recorded on H. armigera during the survey period were Carcelia illota, Apanteles taragamae, Chrysoperla carnea, Nosema sp. and Nomuraea rileyi. All these natural enemies are being reported for the first time on H. armigera in Kerala. The plant aqueous extracts (Acorus calamus Linn. , Andrographis paniculata Wall. and Vitex negundo Linn. ) on their own, are not very highly effective, as they cause only about 30 to 40 per cent mortality at five per cent concentration. All the essential oils (Citronella winterianus Jowitt., Cymbopogon flexuosus Steud., Kaempferia galanga Linn. and Cymbopogon martinii Roxb.) are causing more than 50 per cent mortality except citronella oil (C.winterianus). Palmarosa oil (C. martinii) at five per cent concentration recorded the highest percentage of mortality. In the compatibility study, all the three-entomopathogenic fungi (Nomuraea rileyi, Metarhizium anisopliae and Beauveria bassiana) were found to be incompatible with essential oils and compatible with plant extracts and insecticides. But all the commercial formulations of Bacillus thuringiensis were compatible with plant extracts, essential oils and insecticides. The bioassay of entomopathogens with botanicals and insecticides under laboratory conditions produced the following results In the entomopathogenic fungi and plant extracts combinations, N. rileyi + V. negundo (76.6 per cent) M. anisopliae + V. negundo (63.3 per cent) and B. bassiana + V. negundo (56.6 per cent) recorded the maximum mortality. The treatments N. rileyi+ spinosad (96.6 per cent), B. bassiana+ spinosad and M. anisopliae + spinosad (93.3 per cent) recorded the highest mortality in entomopathogen + insecticide combinations. A drastic reduction in LT50 value was noticed in combination treatments. Among the bacterial formulations + plant extract combination, Delfin + V. negundo (83.3 per cent) recorded the highest mortality percentage among the entire three (Halt, Delfin and Dipel) combination products. The time mortality response was reduced from six to seven days to three to four days in combinations. In the case of bacterial formulations + essential oil, the maximum mortality was recorded in B. thuringiensis (Halt, Delfin and Dipel)+ C. martinii followed by B. thuringiensis + K. galanga. The treatment combinations Halt + spinosad, Delfin + spinosad and Dipel + spinosad recorded the maximum mortality percentage. The mean lethal time could be decreased drastically in combinations when compared to individual treatments. The combination NPV + V. negundo recorded the highest mortality percentage in NPV + plant extract combinations. Among the NPV + essential oil combinations, NPV + K. galanga recorded the highest mortality percentage followed by NPV + C. martinii, NPV + C. flexuosus and NPV + C. winterianus. NPV + spinosad combination recorded the highest mortality percentage in NPV + insecticide combinations. The combined treatment of NPV and B. thuringiensis with plant extracts significantly reduced the digestive enzyme (protease, α - amylase, β - amylase and lipase) activity in the midgut of H. armigera. The results of the field experiment indicate that the percentage mortality was more in biocide (B. thuringiensis, NPV and N. rileyi) and insecticides combinations when compared to the individual treatments. The study has identified eight such combinations, which are immediately field worthy. This technology is considered as eco- friendly and economically viable in nature. The present findings will be of immense help to the ordinary farmer and take him out of debt traps and offer him a better future.