Theses

Browse

Search Results

Now showing 1 - 9 of 29

Open Access
Morphological variations of root knot nematode in vegetables and banana
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2017) Chinchu, P Babu; KAU; Narayana, R
The study entitled “Morphological variations of root knot nematode in vegetables and banana” was conducted at College of Agriculture, Vellayani during 2015-17 with the objective to study the morphological and morphometric variations of root-knot nematode in brinjal, okra, tomato and banana in Kerala. Morphological and morphometrical studies of females, perineal pattern, second stage juveniles and males of root knot nematodes collected from Dhanuvachapuram, Kattakada and Vellayani of Thiruvananthapuram district; Balagram, Pampadumpara and Thovalappady of Idukki district; Chazhoor, Thalikulam and Thaniyam of Thrissur district infecting brinjal, okra, tomato and banana were done and the data was analysed to identify the species. M.incognita (Kofoid & White, 1919) Chitwood, 1949, M. javanica (Treub, 1885) Chitwood, 1949, M. arenaria (Neal, 1889) Chitwood, 1949 and M. chitwoodi Golden, O'Bannon, Santo & Finley 1980 were identified from brinjal, okra, tomato and banana in Thiruvananthapuram, Idukki and Thrissur districts of Kerala. The study indicated M. incognita as the major species of root knot nematode in Thiruvananthapuram district (91.66%) with highest percentage of occurrence in brinjal and tomato (27.77). In Idukki district, the major species of root knot nematode was M. javanica (66.66%) with highest percentage of occurrence from brinjal and banana (33.33). In Thrissur district, M. arenaria was found to be the major species (66.66%) with highest percentage of occurrence in okra (37.5). M. incognita was found to be the major species in brinjal (55.55%), okra (44.44%), tomato (55.55%) and banana (44.44%) in Thiruvananthapuram, Idukki and Thrissur districts. The extent of parthenogenesis of root knot nematode was found to be very high (97.22%) in these populations. Intraspecific morphological variations were observed within M. incognita, M. javanica and M. arenaria with respect to shape of females, length and position of neck, perineal pattern morphology, tail characters including rectum dilation. Interpopulation comparison of mature females, perineal pattern and second stage juveniles of M. incognita showed that the characters length, width, neck length, stylet length, LMB, WMB and ratio a of females, LVS, AVS, ATT and IPD of perineal pattern and body length, stylet length, H-MB, ABW, tail length, ratio c and c’ were recorded as stable characters. Interpopulation comparison of mature females, perineal pattern and second stage juveniles of M. javanica showed that all the characters of females, perineal pattern and second stage juveniles were stable characters and in M. arenaria, the characters like body length, width, neck length, stylet length, LMB and WMB of females, LVS, AVS, ATT and IPD of perineal pattern and length, stylet length, H-MB, ABW and tail length were recorded as stable characters and found useful in characterizing species. Intraspecific morphological and morphometric variations of M. incognita, M. javanica, M. arenaria were recorded from four host plants in three districts in Kerala. M. arenaria and M. javanica showed high variability between the populations compared to M. incognita in Kerala. The study indicated that M. incognita, M. javanica and M. arenaria were the major species infesting vegetables and banana in Kerala. Among the sampled populations, M. hapla was not identified which shows that M. hapla is not common in Kerala conditions. The study recorded the first report of species having morphological and morphometrical characters similar to M. chitwoodi from okra in Thiruvananthapuram which opens way to molecular studies in future.
Open Access
Pathogenicity of indigenous entomopathogenic fungi against select lepidopteran pests
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2016) Praveena, A; KAU; 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.
Open Access
Bioefficacy of Quisqualis indica L. and Samadera indica gaetrn against tobacco caterpillar, spodoptera litura fabricius (LEPIDOPTERA: NOCTUIDAE) in poly house condition
(Depatment of Agricultural Entomology, College of Agriculture, Vellayani, 2016) Anusree, S S; KAU; Nisha, M S
An investigation entitled “Bioefficacy of Quisqualis indica L. and Samadera indica Gaetrn. against tobacco caterpillar, Spodoptera litura Fabricius (Lepidoptera: Noctuidae) in polyhouse condition” was conducted at College of Agriculture, Vellayani during 2014-16. The main objectives were to evaluate the effect of aqueous and solvent extracts of Q. indica flower and S. indica leaf on behavioural and physiological changes of S. litura and to test the potential of the selected plant extracts against S. litura infesting cowpea under polyhouse condition. Aqueous and solvent extracts of Q. indica flower and S. indica leaf were tested for antifeedant and insecticidal action against larvae of S. litura under in vitro condition. Antifeedant activity of aqueous extracts of Q. indica flower and S. indica leaf at 5, 10 and 15 % concentrations showed percentage leaf protection ranging from 0 to 10.98. Solvent extracts viz., ethyl acetate and methanol extracts of Q. indica flower and S. indica leaf at 1.25, 2.5 and 5 % concentrations showed percentage leaf protection ranging from 13.23 to 45.62. Maximum antifeedant activity (45.62 %) was exhibited by methanol extract 5 % of S. indica leaf at 24 hours after treatment. The extracts obtained through cold and soxhlet extraction methods were compared for the antifeedant activity against S. litura. Cold extraction was significantly superior to soxhlet extraction giving leaf protection of 12.72 % for Q. indica flower extract and 21.12 % for S. indica leaf extract. Decreasing trend of antifeedant action with increased exposure time was noticed for both the plants. The insecticidal effect of the extracts was assessed through two application methods, spraying and leaf dip method. Spraying method was effective for both the plant extracts, while leaf dip method was effective for S. indica leaf extract only. Cold extract of Q. indica flower 5% with methanol was found to be highly toxic to S. litura larvae with maximum percentage mortality of 93.51 in spraying method. Methanol cold extract 5 % of S. indica leaf exhibited 73.55 % mortality in spraying method and 41.67 % mortality in leaf dip method. Cold extraction method was found to be significantly superior for both Q. indica flower (70.05 %) and S. indica leaf (50.37 %) than soxhlet extraction in spraying method. The insecticidal effect assessed through dry film method showed that cold extracts of Q. indica flower and S. indica leaf exhibited larval mortality of 36.05 % and 13.52 % respectively. An increase in mortality with increased exposure was observed for both plant extracts. Effect on adult emergence of S. litura (deformation and mortality of larvae, pupae and adults, time taken for pupation, pupal duration, pupal weight and adult longevity) showed that the aqueous and solvent extracts of both plants did not have any influence on larvae, pupae and adults. Cold extracts of Q. indica flower and S. indica leaf exhibited significant larval and pupal mortality ranging from 8.33 to 30 % and 11.67 to 31.98 % respectively. Effect on fecundity and egg hatchability revealed that the plant extracts did not possess significant effect on number of eggs laid and number of eggs hatched. To assess the potential of the selected treatments, methanol extract (5 %) of Q. indica flower and S. indica leaf, a pot culture experiment was done under polyhouse condition on cowpea. It was compared with quinalphos 25 EC 0.05 % and biocontrol agent, Beauveria bassiana (Bb 5) 20 g/L. The percentage leaf area damage in 5 % methanol extract of Q. indica flower and S. indica leaf was 48.56 and 63.64 respectively. Maximum larval mortality of 84.07% was observed in quinalphos 0.05 % followed by 5 % methanol extract of Q. indica flower (61.45 %) and S. indica leaf (40.35 %). . From the above study it is concluded that methanol cold extract (5 %) of flowers of Q. indica and leaves of S. indica have insecticidal action against earlier instars of S. litura. These plants can be exploited for formulating potential green pesticides.
Open Access
Taxonomy of rhynchophorinae (COLEOPTERA: DRYOPHTHORIDAE) of Kerala
(Department of Agricultural Entomology, College of Agriculture, Padannakkad, 2016) Arun Kumar, Singh; KAU; Ramesha, B
The taxonomy of weevils under the subfamily Rhynchophorinae (Coleoptera: Dryophthoridae) was carried at the College of Agriculture Padannakkad, Kasargod, Kerala and seven different agro ecological zones of Kerala during 2014-2016. Study was based on survey carried out in agro and forest ecosystems of Kerala and the samples collected from these ecosystems. Commercially available pheromone traps for the collection of red palm weevil, banana pseudostem weevil and banana rhizome weevil were installed in five agroclimatic regions viz., Northern Zone, (RARS, Pilicode); High range (RARS, Ambalavayal); Central Zone (RARS, Pattambi); Problem zone (RARS, Kumarakom) and Southern Zone (RARS, Vellayani). Traps were also installed in the fields of BRS, Kannara and ORARS, Kayamkulam. The other two weevils, i.e. Diocalandra frumenti and Sitophilus oryzae were collected from households and fields of the aforesaid seven regions. The study also includes specimen stored in Malabar Insect Repository (MIR) and the specimens of Rhynchophorus ferrugineus collected from CPCRI regional station, Kayamkulam, Kerala. An annotated checklist of world Rhynchophorinae was prepared and results revealed that the subfamily Rhynchophorinae includes 955 species under 124 genera and 6 tribes. The distribution of these weevils is more concentrated in Oriental and Neotropical regions (70%). Maximum number of species was described during the 1851-1950. Highest contribution from coleopterists was by Heller (89 species) followed by Chevrolat (76 species), Faust (76 species), Guenther (68 species). Taxonomy ultimately narrowed down to focus on the 770 specimens of five species under five genera viz., Cosmopolites sordidus, Diocalandra frumenti, Odoiporus longicollis, Rhynchophorus ferrugineus and Sitophilus oryzae. Collected specimens of individual species were segregated into different populations according to the morphological variations within the species. The present study of economically important five species had 249 illustrations and 149 line diagrams.Detailed description of all the taxonomic characters like head, rostrum, (dorsal and lateral), antennae, pronotum, elytron, femur, tibia, tarsus, venter and genitalia were studied and presented with line diagrams. Taxonomic description of all the five species were supplemented with standard taxonomic terminology along with genital characters and loaded with the morphometric ratios. The taxonomic key was prepared for all the known species under genera Cosmopolites, Diocalandra, Odoiporus and Rhynchophorus. Based on the morphological characters all five species were segregated in different groups. The taxonomic study revealed that, morphological variations present among the groups may be due to environmental conditions, availability of food, and life stage of the plant on which they are feeding on. All the variations within the species were depicted with the differential distinguishing characters along with line diagrams. Among all five species, major difference was observed within the three groups of Odoiporus longicollis which may be a new species. More morphological and molecular level studies are needed for the confirmation of new species if any.
Open Access
Evaluation of the effect of mineral nutrition in the management of major pests of cowpea
(Department of Agricultural Entomology, College of Agriculture, padannakkad, 2017) Vishnu Priya, T A; KAU; Sreekumar, K M
The experiment entitled “Evaluation of the effect of mineral nutrition in the management of major pests of cowpea” was carried out with the objective to assess the effect of mineral nutrients such as potassium, calcium, magnesium, sulphur, silicon, boron, zinc and copper in the pest management of cowpea var. kanakamony. The study was conducted during two seasons viz., rainy and summer season. The data was subjected to statistical analysis to find out the effect of nutrients on management of major pest and biometric and yield parameters of cowpea. The pot culture experiment was conducted in CRD with 12 treatments including control and absolute control with 3 replications each. The plants were raised in pots in three nutrient regimes namely, potting mixture, potting mixture + NPK and potting mixture + NPK +Ca + Mg. Later, the mineral nutrients were applied as foliar spray with 0.2% concentrated solution at different time intervals viz., the branching stage, the peak branching stage and the flower bud initiation stage. The treatments were : T1 -potting mixture (absolute control), T2 ˗P.M + one nutrient spray, T3 -P.M + two nutrient spray, T4 ˗P.M + three nutrient spray, T5 ˗P.M +NPK (control), T6 ˗P.M + NPK + one nutrient spray, T7 ˗P.M + NPK + two nutrient spray, T8 ˗P.M+NPK+three nutrient spray, T9 ˗P.M + NPK + Ca + Mg, T10 ˗P.M + NPK + Ca + Mg + one nutrient spray, T11 ˗P.M + NPK + Ca + Mg + two nutrient spray, T12 ˗P.M + NPK + Ca+ Mg + three nutrient spray. The results of the experiment revealed that aphid infestation, pod borer infestation, pod bug infestation were significantly influenced by treatment effects. In case of aphids (Aphis craccivora), treatment T8 exhibited minimum population score on stem and pods , minimum percentage of pods and shoots infested in both seasons whereas maximum infestation was observed in T12. Treatments which received macro nutrients has shown lowest aphid score on leaves in both seasons. 133 With respect to pod borers ( Maruca vitrata and Lampides boeticus), T12 recorded minimum infestation in both seasons. In summer, pod borer incidence was comparatively low and treatments which received nutrient spray were found free of borer infestation. Pod borers per plant exhibited the same trend as that of percentage of pods infested. With respect to pod bugs, treatments T10 and T11 exhibited lowest infestation whereas T4 and T1 recorded highest pod bug infested pods in rainy and summer season respectively. The effect of mineral nutrients on biometric and yield characters were influenced significantly in both seasons. Treatment T12 registered the highest leaf area, number of leaves, plant height and total biomass whereas T10 recorded the highest marketable and seed yield. The effect of mineral nutrients on pod length, days to flowering and fresh yield varied with seasons. The highest K and S contents were recorded by T10 and highest Si, B and Zn was recorded by T12, T4 and T11 respectively. On comparing the infestation caused by pests in two seasons, cowpea grown with recommended macro nutrients with foliar spray of minerals exhibited the lowest aphid (T8), pod borer (T12) and pod bug incidence (T10, and T11). From economic point of view, T10 can be recommended with respect to higher B-C ratio, highest marketable seed and fresh yield and comparatively lower infestation.
Open Access
Potential of the narural bio polymers, chitin and chitosan in pest management
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2017) Archana, N H; KAU; Reji Rani, O P
The investigation entitled “Potential of natural bio polymers, chitin and chitosan in pest management” was conducted at College of Agriculture, Vellayani during 2016-17 with an objective to evaluate the insecticidal properties of the natural biopolymers, chitin and chitosan for utilization in crop pest management. Various formulations tested were, chitin (3%, 5%, 7%), chitosan (3%, 5%, 7%), chitosan gel (3%, 5%, 7%), chitin based commercial formulation, Biorakshak 2% and chitosan based commercial formulation, Bioboost 2%. They were tested for their antifeedant, insecticidal, nematicidal and growth promoting properties by leaf dip method and spray methods in laboratory as well as by foliar spray and soil amendments in pot and field studies. Laboratory studies revealed that the pumpkin caterpillar, Diaphania indica Saunders, the leaf beetle Henosepilachna vigintioctopunctata F., pea aphid Aphis craccivora Koch, the root knot nematode, Meloidogyne incognita (Kofoid and White) Chitwood. and the reniform nematode Rotylenchulus reniformis Linford and Oliveira were vulnerable to different chitin and chitosan based formulations whereas, the cut worm Spodoptera litura F. the leaf weevil, Myllocerus viridanus Schoenherr, the pod bug Riptortus pedestris F. and the spiral nematode Helicotylenchus sp. were not. All the formulations tested were safe to the coccinellid predators, Chilomenes sexmaculata F. and Coccinella transversalis F., the syrphid predators, Ischiodon scutellare F. and Xanthogramma scutellare Thorell. and the spiders Tetragnatha mandibulata Walckenaer and Tetragnatha maxillosa Thorell. Antifeedant effect was noticed only D. indica, chitosan 7% being the superior formulation with 43.25 per cent feeding inhibition on first day which decreased to 13.30 per cent on the fourth day. Insecticidal activity was noticed in H. vigintioctopunctata, chitosan gel 7%, being the best treatment causing 100 per cent mortality on seventh day, followed by Bioboost 2% (93.33 per cent mortality). In A. craccivora, chitin 7% caused 100 per cent mortality on fifth day while Biorakshak 2% recorded 91.66 per cent mortality. Nematicidal effect was noticed in M. incognita and R. reniformis. In M. incognita hatching was reduced by 66.6 per cent for chitosan 5% and chitosan 7%, followed by chitin 7% (53.34 per cent). The juveniles (J2) were highly susceptible to all the formulations at 7% causing 100 per cent mortality on second day. Chitin 7% caused 78.54 per cent mortality in R. reniformis on third day. Pot culture studies revealed that, in brinjal, H. vigintioctopunctata population was lowered in plants treated with chitosan gel 7% and chitosan 7%, the population being 2.86 and 4.83 at seven days after treatment (DAT), while in control it was 9.09 per plant. Incidence of M. viridanus and Aphis gossypii Glover was also less in plants treated with chitosan 7% and chitosan gel 7%. The plant height, number of leaves and branches and were also more in the treatment, chitosan gel 7%. Highest yield was recorded in chitosan 7% (149.69 g plant-1 harvest-1). In cowpea, A. craccivora population was significantly reduced (32.97) in plants treated with chitin 7% while in control it was 197.98 at seven DAT. Plants treated with chitin 7%, chitosan gel 7% and Biorakshak 2% showed less damage of mite, Tetranychus sp. Chitin 7% was the best treatment that favored the growth parameters in cowpea. In tomato, M. incognita population in soil was least in plants treated with chitin 7% and chitosan 7% (36 and 52.13) where as in root samples it was least (278.66) in chitin 7% treated plants. Incidence of Liriomyza trifoli Burgess and cercospora leaf spot was also less in these treatments. Field experiment on cowpea revealed that, chitin 7% took seven days to reduce the population of A. craccivora (164.82 plant-1), followed by chitosan 7% and chitosan gel 7% (189.62 and 214.4 respectively), while in plots treated with dimethoate 30EC @ 0.2% there was complete control. Yield plot-1 was 1.76 kg in chitin 7% and it was 1.8 kg in dimethoate 30EC @ 0.2%. In the field trial on tomato, population of nematodes in soil and root sample were less in plots treated with chitin 7% (152.5, 38.75) than in control plots (532.75, 123.75), while in chemical treatment with cartap hydrochloride 4G @ 1 kg a.i.ha-1 it was 72.25 and 5.5 respectively. The incidence of L. trifoli was less in chitin 7% treated plants and that of leaf curl virus was less in treated plants when compared to control. Significantly high yield was noted with crude chitin 7g kg-1 (2.39 kg plot-1) compared to control (1.10 kg plot-1). The study indicated that the potential of natural biopolymers chitin and chitosan can be exploited for the holistic management of crop plants as it has capacity to regulate the population of insect and nematode pests as well as plant diseases. The growth and yield promoting attributes and safety to natural enemies makes them ideal candidates in integrated pests and disease management as well as integrated nematode management programmes.
Open Access
Response of selected okra [Abelmoschus esculentus (L.) Moench] cultivars to root knot nematode meloidogyne incognita (Kofoid and White)
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2017) Chandini, S M; KAU; Susannamma Kurien
Okra [Abelmoschus esculentus (L.) Moench] is an important vegetable crop, popularly known as “bhendi” or “lady’s finger” in India. It is grown in three seasons in the tropical and subtropical regions throughout the world. The nutritional, medicinal and industrial value of okra fruits makes it a promising vegetable crop globally. Pests and diseases are the major limiting factors for okra cultivation. Among them plant parasitic nematodes are the most serious. Root-knot nematode, Meloidogyne incognita is one of the most economically damaging genera of plant parasitic nematodes which causes 31 per cent of yield loss in India (Jain et al., 2006). Several methods have been developed for the management of the nematode. Use of chemical nematicides is the most effective, which brings about 80 per cent reduction in nematode population. Host resistance is an important component of integrated nematode management. Use of cultivars resistant to M. incognita is one of the best alternatives, which is specific, environmentally safe and economically feasible. In this context, a study entitled “Response of selected okra [Abelmoschus esculentus (L.) Moench] cultivars to root knot nematode, Meloidogyne incognita (Kofoid and White)” was carried out in the Department of Agricultural Entomology, College of Horticulture, Vellanikkara during January 2016 to October 2016, with the objective of screening selected okra cultivars against M. incognita and to elucidate the biochemical basis of resistance. Thirty okra cultivars comprising twenty one accessions from NBPGR Regional Station, Thrissur, eight released varieties and a highly susceptible check (Arka Anamika) were screened for their reaction to root knot nematode M.incognita. Pot culture experiment was conducted in Completely Randomized Design with three replications and 30 treatments. Okra plants were inoculated with M.incognita @ one second stage juvenile per gram of soil after two weeks of seed germination. Biometric characters like plant height, number of leaves, number of flowers, number of fruits and fruit weight were recorded at fortnightly intervals from the time of inoculation till uprooting. Shoot weight, root weight, root knot number and nematode population in soil and roots were also recorded when the plants were uprooted i.e. three months after inoculation. Significant reductions in all the biometric parameters were observed over their respective controls in all the cultivars. The per cent decrease in these parameters were higher in highly susceptible and susceptible cultivars than moderately resistant cultivars. Based on the number of galls per 10 g roots, indexing was done on 1-5 scale and the okra cultivars were categorized as highly resistant, resistant, moderately resistant, susceptible and highly susceptible (Devi et al., 2014). None of the cultivars were highly resistant or resistant whereas four cultivars viz., IC 117238, IC 117251, IC 111507 and Varsha Uphar with root knot index 3 were classified as moderately resistant. Seven cultivars viz., Manjima, IC 111536, IC 117260, IC 111500, IC 111247, IC 469689 and IC 111517 were found to be susceptible with root knot index 4. Rest of the nineteen cultivars viz., Aruna, Kiran, Anjitha, Salkeerthi, Susthira, Arka Anamika, Pusa Sawani, IC 218900, IC 112457, IC 329360, IC 045819, IC 117308, IC 117228, IC 111525, IC 111514, IC 329357, IC 282275, IC 305634 and IC 045515 were classified as highly susceptible with root knot index 5. Biochemical parameters like total phenol, peroxidase (PO), total sugar and reducing sugar of both control and inoculated roots of okra cultivars were estimated at three months after inoculation based on standard procedures to analyze the biochemical bases of resistance. An increase in total phenol and peroxidase activity was noticed in moderately resistant cultivars than susceptible cultivars whereas total sugar and reducing sugars were higher in highly susceptible cultivars. Correlation analysis showed a significant negative correlation between total phenol content and peroxidase activity with number of root knots, root knot index and population of M. incognita in root and soil. A significant positive correlation of total sugar and reducing sugar was recorded with number of root knots, root knot index and population of M. incognita in root and soil. The present study revealed that IC 117238, IC 117251, IC 111507 and Varsha Uphar were moderately resistant. Hence these cultivars could be utilized as resistant sources for further breeding programmes. Field trials in sick plots also need to be conducted to study the field performance of the moderately resistant cultivars.
Open Access
Bioefficacy of the acaropathogen, acremonium zeylanicum (petch) gams and evans against the spider mite, tetranychus truncatus ehara (acari: tetranychidae)
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2017) Alka Sherief; KAU; Haseena Bhaskar
Spider mites (Prostigmata: Tetranychidae) cause severe injury to vegetables grown under both protected and open field conditions. Awareness on the ill effects associated with the use of synthetic chemicals in pest management has resulted in an increased demand for safe to eat food. Hence, ecofriendly strategies for the management of mite assume high priority. Investigations on potential natural enemies of spider mites by All India Network Project on Agricultural Acarology (AINPAA) have identified an acaropathogenic fungus, Acremonium zeylanicum (Petch) Gams and Evans from the spider mite, Tetranychus urticae Koch on brinjal from Thrissur district. The present study was undertaken at the Department of Agricultural Entomology, College of Horticulture, Vellanikkara during 2016 - 2017 in the above context to investigate the biocontrol potential of the acaropathogen, A. zeylanicum against the predominant species of spider mite in Kerala, Tetranychus truncatus Ehara; to assess the sensitivity of the acaropathogen to selected novel acaricides and botanicals and also to evaluate its safety to the predatory mite, NeosAcremonium zeylanicum was evaluated along with two novel acaricides and two botanicals against T. truncatus on cucumber under polyhouse conditions. A. zeylanicum significantly reduced mite population seven days after treatment at both 1×108 spores ml-1 (72.71%) and 1×107 spores ml-1 (55.03%). However the novel aceiulus longispinosus (Evans). Laboratory bioassay conducted to evaluate the efficacy of A. zeylanicum at five different concentrations viz.1×105, 1×106, 1×107, 1×108 and 1×109 spores ml-1 against T. truncatus recorded more than 50 per cent mortality of adult mites within six days at both 1×108 and 1×109 spores ml-1. The mortality increased with increase in concentration of the fungus and also with progress in time. The highest mortality of 68.36 per cent was recorded by A. zeylanicum applied at the rate of 1×109 spores ml-1 seven days after treatment, which was on par with 61.65 per cent mortality recorded at 1×108 spores ml-1. The fungus was more effective against adult stage compared to egg stage of T. truncatus. The highest mortality of egg stage (41.33%) was recorded four days after the treatment at 1×10 9 spores ml-1. aricides (spiromesifen & diafenthiuron) and botanicals (neem oil & azadirachtin) were significantly superior to the acaropathogen in reducing the mite population. Compatibility study of A. zeylanicum with different agrochemicals revealed that the acaricides, spiromesifen and fenpyroximate were relatively safer to the fungus. The fungicides, Curzate M8 (Cymoxanil 8% + Mancozeb 64 %) and Equation Pro (Fomaxadone 16.6%+ Cymoxanil 22.1%) recorded highest per cent inhibition and were followed by the acaricides, fenazaquin, diafenthiuron, propargite and the botanicals azadirachtin and neem oil. Laboratory evaluation of safety of A. zeylanicum to the predatory mite N. longispinosus showed that the predatory mite was less susceptible to A. zeylanicum than the prey mite, T. truncatus. The pathogen did not have any ovicidal effect and had caused much lower mortality of 20 per cent on adults of N. longispinosus at the highest dose of 1×108 spores ml-1. The study indicated the potential of A. zeylanicum in reducing mite population significantly both in laboratory and polyhouse. The pathogen was found to be compatible with commonly used acaricides and also was safe to the predominant predatory mite species in vegetable ecosystems. Thus it can be inferred that the acaropathogen A. zeylanicum could be a valuable component in integrated mite management programme in vegetables.
Open Access
Bioecology of small hive beetles and assessment of their damage in stingless bee colonies
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2017) Gayathri, P Bose; KAU; Amritha, V S
The study entitled “Bioecology of small hive beetles and assessment of their damage in stingless bee colonies” was conducted with the objectives to study the incidence, bioecology and the extent of damage by small hive beetles in stingless bee colonies. The study was conducted during the period 2015-2017 at Department of Agricultural Entomology, College of Agriculture,Vellayani. A survey was conducted in Southern districts of Kerala viz., Thiruvananthapuram, Kollam and Pathanamthitta. Seven beetles (five nitidulids, one cryptophagid and one tenebrionid) were collected from the hives during the survey. Among these, the nitidulid beetle which caused the primary infestation is identified as Epuraea latissima Kirejtshuk and it is the first report from stingless bee hive. Monthly incidence of the hive beetle revealed that peak period of infestation was recorded from Thiruvananthapuram in the month of June, whereas in Kollam district, it was during June and July. However, the incidence was recorded only during the month of May from Pathanamthitta district. Among the three districts, highest incidence of small hive E. latissima beetle was recorded from Kollam (19.00 %), followed by Thiruvananthapuram (16.00 %) and Pathanamthitta (3.00 %). The type of hive used for maintaining the stingless bee colony is an important factor which determines the hive beetle incidence. Majority of bee keepers maintained stingless bees in wooden box (59.33 %) followed by mud pots (18.66 %). Among the wooden boxes, the incidence was more prominent in bad quality wooden boxes (made of locally available soft wood) in Thiruvananthapuram (60 %), Kollam (50 %) and Pathanamthitta districts (15 %). Studies on the influence of height of the stingless bee hive from the ground level with the hive beetle incidence revealed that the hives kept at 3-4 m recorded the highest incidence (24.79 %) followed by 2-3 m (8.04 %). The colonies maintained at a height of > 4 m were free from hive beetle incidence. Regarding the incidence of small hive beetle in different shade conditions, highest hive beetle incidence (50.70 %) was recorded from apiaries under high shade condition (>80 % canopy coverage) followed by moderate (30-80 % canopy coverage) shade condition (0.90 %). The damage symptoms recorded from infested colonies were fermentation and discolouration of honey due to the feeding and defecation by the beetle larvae and a light brown coloured undistinguished mass of hive contents. Apart from the small hive beetles, black soldier fly, Hermetia illucens L., pollen mites and ants were also documented as pests of stingless bees from the apiaries of Southern Kerala. Regarding the studies on biology of the hive beetle, egg period, larval and pupal period of the beetle was recorded as 2.2 ± 0.537, 14.2 ± 1.686 and 17.77 ± 0.963 days respectively. The length and width of egg, larva, pupa and adult was recorded as 0.551 ± 0.037× 0.173 ± 0.003 mm, 4.471 ± 0.159 × 1.062 ± 0.025 mm, 2.515 ± 0.123× 1.1124 ± 0.044 mm and 3.0897 ± 0.454 × 1.378 ± 0.0758 mm respectively. The larvae caused severe damage by tunneling and feeding the pollen pots while the adults nibbled the hive contents. Studies on the correlation between larval population and weather parameters showed a significant positive correlation with rainfall and relative humidity. Highest population of grubs was recorded on 2nd fortnight of May. The time taken by the grubs for complete destruction of pollen block (4 cm3) was recorded as 16 days, whereas for the destruction of brood cells and honey block of 4 cm3, it took 13.50 days and 10.83 days respectively. The small hive beetle which primarily infested the stingless bee colonies is identified as the nitidulid beetle, E. latissima. The hive beetle incidence can be reduced by using good quality wooden boxes, where the bad quality wooden boxes along with high rainfall predisposes hive beetle incidence in the apiaries.

Theses

Browse

Thesis Type

Type

Author

Date

Subject

Rating Count

Search Results