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Open Access
Ecological Management of Coconut root grub, Leucopholis coneophora Burm
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2019) Melvin Mohan, S; KAU; SanthoshKumar, T
The study entitled ‘Ecological management of coconut root grub, Leucopholis coneophora Burm.’ was conducted at the Department of Agricultural Entomology, College of Agriculture, Vellayani, and College of Agriculture, Padannakkad during 2017 to 2019. The main objectives were to study the efficacy of botanical insecticides and biocontrol agents against coconut root grub, L. coneophora. The entire study consisted of two parts, laboratory evaluation and pot culture experiment. The laboratory experiment was conducted for screening various entomopathogenic fungi (EPF), entomopathogenic nematodes (EPN), botanicals and chemical insecticides against coconut root grub. Metarhizium anisopliae (Ma 4) and Beauveria bassiana (Bb 5) at different concentrations (1 x 108, 1 x 109 and 1 x 1010 spores mL-1) were tested. Entomopathogenic nematodes Steinernema carpocasae and Heterorhabditis bacteriophora at 100, 500 and 1000 IJ mL-1 were used for screening. The botanicals such as Azadirachta indica, Gliricidia maculata, Clerodendron infortunatum and Chromolaena odorata @ 25 g kg-1 of soil were screened for their efficacy against root grub. The chemicals used for the experiment comprised of chlorantraniliprole 0.4% G @ 75g a.i ha-1, fipronil 0.3% G @ 75g a.i ha-1 and spinosad 45% SC @ 73g a.i ha-1. Chlorpyriphos 25 % EC @ 225 g a.i ha-1 was used as a chemical check along with untreated control. Fifteen kilograms of sterilized moist soil was taken in a plastic basin and fresh potato tubers were given as feed for root grub. Three grubs were released into the basin and treatments were given one week after the release of grubs. The screening experiment using EPF consisted of eight treatments with three replications. The application of M. anisopliae @ 1 x 1010 spores mL-1 was found to be the most effective (100 % mortality) EPF against root grub and was on par with chemical check at 14 days after treatment (DAT). At 21 DAT, B. bassiana @ 1 x 1010 spores mL-1 resulted 100 per cent mortality and was on par with M. anisopliae @ 1 x 1010 spores mL-1 and the chemical check. At 28 DAT, M. anisopliae @ 1 x 1010 spores mL-1 and B. bassiana @ 1 x 1010 spores mL-1 brought about 100 per cent mortality of grubs, which were on par with the chemical check chlorpyriphos 20 % EC @ 225g a.i ha-1 (100 %), followed by M. anisopliae @ 1 x 109 spores mL-1 (92.58 %) and B. bassiana @ 1 x 109 spores mL-1 (85.17 %). The screening experiment with EPN consisted of eight treatments with three replications and the results revealed that all the treatments except chemical check failed to cause infection on grubs upto 10 DAT. Among the botanicals, A. indica application showed 48.14 per cent mortality of root grubs followed by C. infortunatum (37.03 %) at 30 DAT. The effect of chemical insecticides on root grub was conducted with five treatments and four replications. Fipronil 0.3% G @ 75g a.i ha-1 exhibited 97.22 per cent mortality and was on par with the chemical check at nine DAT followed by chlorantraniliprole 0.4% G @ 75g a.i ha-1 (74.99 %). Promising treatments viz. M. anisopliae (1 x 1010 spores mL-1, 1 x 109 spores mL-1), B. bassiana (1 x 1010 spores mL-1, 1 x 109 spores mL-1), chlorantraniliprole 0.4% G @ 75g a.i ha-1, and Fipronil 0.3% G @ 75g a.i ha-1 from laboratory experiments were selected and evaluated in a pot culture experiment and were laid out in CRD with eight treatments and three replications. Chlorpyriphos 25 % EC @ 225 g a.i ha-1 was used as a chemical check along with untreated control. Fodder grass variety CO-3 was raised in pots and first instar grubs were released after the establishment of the crop. The results of the pot culture experiment indicated that the application of fipronil 0.3% G @ 75g a.i ha-1 resulted in 100 per cent mortality and was on par with the chemical check at 28 DAT followed by M. anisopliae @ 1 x 1010 spores mL-1 (85.17 %). The treatments B. bassiana @ 1 x 1010 spores mL-1 (77.77 %), chlorantraniliprole 0.4 % G @ 75g a.i ha-1 (74.06 %) and M. anisopliae @ 1 x 109 spores mL-1 (74.06 %) were found to be on par at 28 DAT. From the present study, it can be concluded that the application of entomopathogenic fungi M. anisopliae @ 1 x 1010 spores mL-1 is a promising option for the management of first instar grubs of L. coneophora followed by B. bassiana @ 1 x 1010 spores mL-1. Soil application of neem leaves @ 25 g kg-1 of soil can enhance the suppression of root grubs. The results clearly indicate the possibility of reducing the use of chemical insecticides by resorting to botanicals and biocontrol agents.
Open Access
Biosystematics and barcording of pteromalidae (Hymenoptera:Chalcidoidea) of Kerala
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2019) Manu Govind, K.K.; KAU; Shanas, S
The study entitled " Biosyslematics and barcoding of Pteromalidae (Hymenoptera: Chalcidoidea) of Kerala" was conducted during the 2017-19 at the Department of Agricultural Entomology, College of Agriculture, Vellayani with the objective of identification, morphological and molecular characterization and documentation of parasitoid wasps (Pteromalidae) of Kerala. The base material for study was field collected specimens. Purposive sampling was carried out in 38 locations spread across 14 districts of Kerala. The specimens were collected by random sweep net method. The collections were made in the morning and afternoon when the insect activity was at the peak. The sweep contents were immediately transferred into absolute alcohol and the location and date of collection were recorded on the containers. The field collected specimens were examined under high power stereo microscope and initially all the specimens coming under Chalcidoidea were sorted out based on superfamily characters and stored in labelled vials in absolute alcohol. Pleomalid wasps were separated out from these vials and stored in alcohol in another set of vials according to location. The specimens were card mounted for morphometric analysis and characterization. The study revealed 2 genera and 4 species of Ptcromalids which are new to the World of science. The two new genus fall under the subfamily Miscogasterinae and Pteromalinae respectively. The four new speicies discovered are, Dinarmus sp. nov. 1, Mokrzeckia sp nov. 1, Panstenon sp. nov. 1 and Pansienon sp. nov. 2. The Dinarmus sp. nov. 1 was compared to Dinarmus maculatus^ Mokrzeckia sp. nov. 1 was compared to M pint and Panslenon sp. nov. 1 and P. nov. 2 was compared to P. collare
Open Access
Barcoding and biosystematic studies on Hymenopteran pollinators of cucurbitaceous vegetables
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2019) Erra Harisha; KAU; Shanas, S P
The study entitled “Barcoding and biosystematic studies on hymenopteran pollinators of cucurbitaceous vegetables” was conducted during the year 2017- 2019 at the Department of Agricultural Entomology, College of Agriculture, Vellayani with an objective to study the diurnal activity and dynamics of hymenopteran pollinators of cucurbitaceous vegetables and to explore their morphological and molecular diversity. To determine the composition and relative abundance of different hymenopteran pollinators visiting the flowers of five selected cucurbitaceous vegetables viz., culinary melon (Cucumis melo var. acidulus), bitter gourd (Momordica charantia L.), ash gourd (Benincasa hispida Thunb. and Cogn.), pumpkin (Cucurbita moschata L.) and ridge gourd (Luffa acutangula (Roxb.) L.) collections were made throughout the blooming period in Thiruvananthapuram and four other districts of Kerala viz., Kollam, Pathanamthitta, Alappuzha and Kasaragod from 06:00 h to 18:00 h of the day with a cone type hand net. Among the above mentioned vegetables, culinary melon was selected for detailed study on diurnal activity at College of Agriculture, Vellayani. The study on composition and relative abundance of hymenopteran pollinators revealed that, A. cerana indica was the dominant pollinator in culinary melon (42.51 %), pumpkin (38.76 %) and ridge gourd (35.16 %) whereas, T. travancorica was the dominant pollinator in bitter gourd (31.86 %) and ash gourd (33 %). Observations on diurnal activity were carried out at College of Agriculture, Vellayani in culinary melon during two crop seasons for 3 weeks at weekly intervals. For foraging rate, the number of flowers visited by each bee for 1 minute and for foraging speed, time spent by each bee per flower were observed respectively. During two seasons, the foraging speed of A. cerana indica, T. travancorica and Halictus sp. was found to be highest during 10:00-11:00 h (10.61 and 10.63, 11.23 and 11.46, 10.26 and 10.40 seconds) respectively. The foraging speed of C. hieroglyphica and Lasioglossum sp. was found to be highest during 09:00-10:00 h (9.02 and 9.11, 11.06 and 11.30 seconds) respectively. The foraging rate of T. travancorica, C. hieroglyphica and Lasioglossum sp. was found to be highest during 10:00-11:00 h (9.16 and 9.23, 4.83 and 4.85 flowers/m2/5 min) respectively. The foraging rate of A. cerana indica and Halictus sp. was found to be highest during 11:00-12:00 h and 09:00-10:00 h (10.60 and 10.88, 4.03 and 4.13 flowers/m2/5 min) respectively. Samples which were unidentified through morphological characterization were given for DNA barcoding. The sequence of 2 samples viz., Tetragonula sp. nov.1 and T. travancorica were obtained. Among these, new species (Tetragonula sp. nov.1) of stingless bee, based on adult worker specimen is described. Differences in morphology and genetic analysis based on partial sequences of the mitochondrial COI gene barcode region support the recognition of the new species. The above results revealed that A. cerana indica was dominant in culinary melon, pumpkin, and ridge gourd and T. travancorica was dominant in bitter gourd and ash gourd. The foraging speed during two seasons in the descending order was T. travancorica > Lasioglossum sp. > A. cerana indica > Halictus sp. > C. hieroglyphica. The foraging rate during two seasons in the descending order was A. cerana indica > T. travancorica > C. hieroglyphica > Lasioglossum sp. > Halictus sp. Among the pollinators, five species viz., P. phalerata phalerata, C. annulata annulata from ash gourd, M. disjuncta from bitter gourd, C. simillima, and C. unimaculata javanica from culinary melon were reported for the first time pollinating cucurbitaceous vegetables. Tetragonula sp. nov.1 of stingless bee, collected from pumpkin flower, is the new species report from the study and it is morphologically characterised.
Open Access
Compactibility and synergism of the entomopathogentic fungus lecanicillium saksenae (Kushwaha ) Kurihara and Sukarno with other crop protectants
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2019) Keerthana, K; KAU; Reji Rani, O P
The study entitled “Compatibility and synergism of the entomopathogenic fungus Lecanicillium saksenae (Kushwaha) Kurihara and Sukarno with other crop protectants” was carried out in College of Agriculture, Vellayani and Integrated Farming System Research Station, Karamana during 2017-2019 with the objective to assess the compatibility of L. saksenae with botanical insecticides, chemical insecticides, fungicides other entomopathogenic fungi and to evaluate synergistic insecticidal effect. In vitro studies on compatibility was carried out using poisoned food technique, by assessing radial growth, sporulation and germination of L. saksenae. Botanicals tested were aqueous and solvent extracts of neem seed kernel, neem leaves and neem oil emulsion. Among them, lower dose of neem oil emulsion (NOE) 0.5% did not affect the mycelial growth of the fungus. It was 6.27 cm on 14th day after inoculation which was on par with that of control (6.17 cm). Sporulation of the fungus was affected by all the botanicals, with least inhibition in lower dose of aqueous neem leaf extract (NLE (A)) 1% (4.41 x 107 spores mL-1). The corresponding count in untreated medium was 7.57 x 107 spores mL-1. Viability of the fungus was not affected by the lower dose of neem seed kernel extract (NSKE (A)) 0.5%, when compared to control (97.67 % and 99%). Biological index (BI) indicated that aqueous and solvent extracts of NSKE (0.5%), NSKE (A) 1%, NLE (A) 1% and NOE (0.5%) were compatible with L. saksenae, BI values being 75, 69, 70, 75 and 67, respectively. Among the insecticides tested, flubendiamide 39.35 SC was least inhibitory to the growth of L. saksenae, both at half as well as recommended doses (5.92 cm and 5.88 cm), followed by half the recommended doses of thiamethoxam 25 WG (5.88 cm) and chlorantraniliprole 18.5 SC. (5.78cm). The corresponding growth in untreated medium was 6.10 cm. Sporulation in chlorantraniliprole at the recommended dose and control was same (1.35 x 107 spores mL-1). Spore viability was affected by all the insecticides. Germination in imidacloprid was highest among the treatments (85.67 per cent). BI value indicated that imidacloprid, thiamethoxam, flubendiamide and chlorantraniliprole at recommended and half doses were compatible with L. saksenae. (67-94). None of the fungicides tested, were compatible with L. saksenae. B. bassiana at 108 spores mL-1 was found to be compatible with L. saksenae at 107 spores mL-1 based on mortality of treated rice bugs. Treatments L. saksenae and L. saksenae + B. bassiana caused 100 per cent mortality on fourth and fifth day after spraying in nymphs and adults of rice bug. Synergism studies revealed that, on the first day L. saksenae (107 spores mL-1) and L. saksenae + NSKE (A) 0.5% were equally effective causing 83.33% mortality in nymphs, while in adults L. saksenae was superior to its combination (66.67 and 60%). L. saksenae + thiamethoxam 0.0025% exhibited significantly higher mortality in adults (70%) on the first day while in L. saksenae it was 66.67%. For nymphs, L. saksenae and L. saksenae + thiamethoxam 0.0025% was equally effective (83.33% mortality). In both adults and nymphs, L. saksenae was more effective causing 75 per cent and 85 per cent mortality on the first day, while its combination with B. bassiana caused 65per cent and 80 per cent mortality. L. saksenae and its combinations with botanicals, insecticides and microbials had higher feeding inhibition in rice bugs. Under field conditions, L. saksenae at 107spores mL-1 + thiamethoxam 0.0025% and L. saksenae + B. bassiana at 108 spores mL-1 recorded significantly higher population of 3.5 and 2.75 bugs per plot, compared to that of L. saksenae (2.25 bugs per plot). Population of natural enemies did not vary significantly among the treated and untreated plots. Yield recorded at harvest was higher in plots treated with L. saksenae (1.38 kg plot-1) which was followed by combination spray of L. saksenae and B.bassiana (1.32 kg plot-1) It is concluded that L. saksenae is compatible with the botanicals such as neem seed oil emulsion 0.5% and neem seed kernel extract 0.5%. It was also compatible with the new generation insecticides flubendiamide, chlorantraniliprole, thiamethoxam and imidacloprid. Among the microbials, B. bassiana was not inhibitory. Fungicides such as carbendazim, mancozeb, copper oxychloride, hexaconazole and azoxystrobin were inhibitory to L. saksenae. None of the botanicals, insecticides, fungicides or microbials had synergistic effect with L. saksenae. In the management of rice bug L. saksenae was superior to its combination treatments and it did not affect the natural enemy population in rice ecosystem.
Open Access
Insecticide resistance in spiralling whitefly,aleurodicus dispersus russell(hemiptera:aleyrodidae) and its management
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2019) Aura Senson; KAU; Ambily Paul
A study on “Insecticide resistance in spiralling whitefly, Aleurodicus dispersus Russell (Hemiptera: Aleyrodidae) and its management” was done at College of Agriculture, Vellayani and farmer’s field at Kalliyoor during 2018 to 2019. Tokassess thehinsecticide resistance in the fieldhpopulation of spiralling whitefly, A. dispersus and to evaluate the efficacy of new generation insecticides against resistant population of A. dispersus were the objectives of the study. Bioassaykwas carriedLout to assess the insecticideHresistance in field population of A. dispersus collectedUfromHthree different locations (location ISreekaryam, location II-Vellayani and location III-Kalliyoor) based on the intensity of insecticide application. A series of concentrations of three insecticides viz., quinalphos, fenvalerate and imidacloprid were prepared in aqueous solution and leaf dip bioassay was done using the field population of whiteflies collected from three locations. Results revealedDthatkpopulation collected from location-I (Sreekaryam) was foundhto begsusceptible to insecticides with resistance ratio-1 for all three insecticides, which was considered as reference strain. Population collectedgfrom location-II (Vellayani) showed higher resistance with resistance ratio of 2.60, 2.90 and 1.85 and population from location-III (Kalliyoor) was found to be moderately resistant with resistance ratio of 1.14, 1.62 and 1.28 with respect to quinalphos, fenvalerate and imidacloprid respectively. Laboratoryyexperiments were conductedutotevaluateethedefficacy ofdnew generationdinsecticides viz. buprofezin 25% SC @ 75 g.a.i ha-1, clothianidin 50% WDG @ 20 g,a.i ha-1, cynantraniliprole 10.26% OD @ 90 gfa.i ha-1, dinotefuran 20% SG @ 25 g a.i ha-1, flonicamid 50% WG @ 75 g a.i ha-1, thiamethoxam 25%WG @ 50 g a.i ha-1 and thiamethoxamt12.6% + lambdadcyhalothrin 9.5% ZC @ 33+15.75 g a.i ha-1against resistant population of A. dispersus in tomato plants. The results revealed that significantly higher mortality was observed in A. dispersus treated with thiamethoxamg12.6% +hlambda cyhalothrin 9.5% ZC @ 33+15.75 g a.i ha-1 (100%), followed by clothianidin 50% WDG @ 20 g a.i ha-1 (80%) and flonicamid 50% WG @ 75 g a.i ha-1 (66.67%) after 0.75 hours of treatment. Field experiment was conducted by using tomato plants (var. Vellayani Vijay) at Vellayani from where resistant population was collected with three effective insecticides selected from laboratory along with control. No whiteflies were seen in thiamethoxamt12.6% + lambdatcyhalothrin 9.5% ZC @ 33+15.75 g a.i ha-1 treated plants followed by clothianidin 50% WDG @ 20 g a.i ha-1 (9.20) and flonicamid 50% WG @ 75 g a.i ha-1(11.80) after one day of spraying. Studies on the dissipation of residues of effective insecticides viz., thiamethoxam 12.6% + lambda cyhalothrin 9.5% ZC @ 33+15.75 g a.i ha-1, clothianidin 50% WDG @ 20 g a.i ha-1 and flonicamid 50% WG @ 75 g a.i ha-1 were conducted in tomato plants at farmer’s field at Kalliyoor. Tomato fruits collected at 0,1,3,5,7,10,15 and 30 days after application of insecticides at recommended dose and results showed that insecticides dissipated within 10 days with half- lives of 4.05, 3.42, 8.92 and 7.82 days respectively. The risk assessment studies also proved the safety of insecticides for the end users. The present study revealed the development of insecticide resistance in the field population of A. dispersus against fenvalerate and quinalphos. Thiamethoxam 12.6% + lambda cyhalothrin 9.5% ZC @ 33+15.75 g a.i ha-1 followed by clothianidin 50% WDG @ 20 g a.i ha-1 and flonicamid 50% WG @ 75 g a.i ha-1 could be recommended against the resistant population of A. dispersus in tomato. Dissipation and risk assessment studies also supported the result by establishing their safety to consumers. Further studies have to be taken up to develop and popularize Insecticide Resistant Management strategies against A. dispersus by developing Good Agricultural Practices on efficient use of insecticides and to conserve the ecosystem for sustainable pest management.
Open Access
Histomorphology of Indian bee (Apis cerana indica Fab.) supplemented with probiotics
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2019) Akhila Pahee; KAU; Amritha, V S
The study entitled “Histomorphology of Indian bee (Apis cerana indica Fab.) supplemented with probiotics” was undertaken at College of Agriculture, Vellayani, Thiruvananthapuram during 2017- 19. The main objective was to assess the histomorphology of midgut of Indian bee’s (Apis cerana indica Fab.) suffering from various stressors (pathogens and insecticides) and, after being fed with probiotics. Purposive sampling was conducted at Thiruvananthapuram, Kollam, Pathanamthitta and Idukki districts for the present study. Twelve larvae (3 to 4 days old) each from naturally occurring feral colony, domesticated colonies which were fed with and without sugar syrup, naturally infected ones with bacterial brood disease as well as larvae fed with insecticide treated royal jelly (Thiamethoxam 25% WG) were collected and subjected to histomorphological evaluation. Also, the effect of probiotics on larvae under different stress conditions were also evaluated. The study mainly focused on the variations in the midgut histology of the larvae. The midgut of the honey bee larvae from feral colony had high epithelial integrity, well defined brush bordered microvilli which probably helps in the easy absorption of nutrients, prominent regenerative cells that is responsible for epithelial cell replacement and copious secretion of peritrophic membrane that are intented for the protection of the midgut from abrasive food particles, pathogen and toxins. The larvae of the colonies which were not fed with sugar also had similar histology. Histomorphological studies of honey bee larvae fed with sugar syrup, revealed the adverse effect of sugar on midgut cells viz., presence of vacuoles in the epithelium, absence of microvilli, reduced number of regenerative cells and uneven peritrophic membrane secretion. Studies on the midgut histomorphology of bacterial brood disease infected larvae indicated necrosis with picnotic or karyorrhectic nuclei, moderate to severely vacuolated cytoplasm, inconspicuous microvilli and distorted peritrophic membrane. Only occasional regenerative cells were apparent. The midgut epithelial cells of the larvae fed with insecticide, thiamethoxam 25% WG @ 0.05g L-1 exhibited only the presence of vacuoles of variable sizes. The midgut histomorphology of honey bee larvae treated with the probiotic, Darolac (1.25 x 109 cells of Lactobacillus acidophilus, L. rhamnosus, Bifidobacterium longum and Saccharomyces boulardi g -1 @ 1.2 g L-1 of water and sugar syrup) at weekly intervals for a period of four weeks was also evaluated. An increased cell activity which was indicated by the prominent aposematic secretion towards the gut lumen was observed in those larvae supplemented with probiotics when compared with that of the normal larvae from feral colony. Apart from these, enhanced integrity of the epithelial columnar cell, even distribution of microvilli and augmentation in the secretion of peritrophic membrane was also recorded. The present investigation revealed that the larvae fed with sugar syrup or those exposed to various stressors (disease and insecticide) had adverse effect on the midgut where they exhibited necrosis of epithelial cells, broken and unclear microvilli and distorted peritrophic membrane. Thus, the disruption of epithelial cells hindered the absorption of nutrients and water which led to the death of honey bee larvae. When probiotic (Darolac @ 1.2 g L-1) was supplemented to honey bee larvae under different stressors, it helped in mitigating the intensity of cell necrosis by restoration of regenerative cells and the larval health was found to be recovered which was indicated by the even distribution of microvilli.
Open Access
Endophytic association of entomopathogenic fungi with rice and cowpea
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2019) Divyashree, C; KAU; Reji Rani, O P
The study entitled ‘Endophytic association of entomopathogenic fungi with rice and cowpea’ was carried out in the Department of Agricultural Entomology, College of Agriculture, Vellayani, Thiruvananthapuram, during the year 2017-19, with the objective to examine the endophytic association of entomopathogenic fungi in rice and cowpea. The entomopathogenic fungi, evaluated were Beauveria bassiana, Metarhizium anisopliae, Lecanicillium lecanii and Lecanicillium saksenae. They were tested through seven inoculation methods viz., seed coating, seed soaking, radicle dressing, root dipping, soil drenching, foliar spraying and bloom spraying by inoculating the conidial suspension at their effective doses. Among the four entomopathogenic fungi inoculated, B. bassiana, M. anisopliae and L. saksenae were found to colonise rice plants. B. bassiana was found to colonise in stem and roots, while M. anisopliae preferred stem. Both B. bassiana and M. anisopliae colonized effectively by seed soaking method. L. saksenae colonised in the stem and roots in seed soaking, in the roots in soil drenching and in the leaves in foliar spraying method. In plants, B. bassiana and M. anisopliae persisted up to 15th day after inoculation (DAI), while L. saksenae persisted till 45th DAI. In soil, L. saksenae persisted in soil up to 45th day, while other fungi could not be retrieved from soil. L. lecanii could not be retrieved from any of the plant parts or soil up to 45th DAI. Thirteen natural endophytes were isolated from rice, which included growth promoters with nitrogen fixing properties, gibberellic acid production properties, saprophytes and plant pathogens. They were identified with the help of colony and conidial characters. Those fungal endophytes whose identity could not be confirmed were characterised at molecular level through ITS sequencing, and bacterial endophytes through 16S sequencing. The most dominant endophyte in rice was the fungus, Neocomospora rubicola, a known plant pathogen followed by the nitrogen fixing bacterium Burkholderia cepacia. Colonisation of fungal bacterial association Sarocladium oryzae + Kosakonia sacchari was also dominant in the stem. S. oryzae is a known plant pathogen while K. Sacchari is a nitrogen fixing bacterium. The other endophytes with less frequency of occurrence were Pestalotiopsis microspora, Cladosporium sp., Microdochium fisheri, Fusarium solani, Aspergillus and Penicillium. Experiments in cowpea revealed that all the four fungi could successfully colonize different plant parts. Foliar spraying was the best method in cowpea to get endophytic association of all the four fungi, while M. anisopliae could also be retrieved through seed soaking and root dipping methods. B. bassiana, M. anisopliae and L. saksenae were found to colonise leaves, stem and roots, while L. lecanii colonised only on leaves. In cowpea plants, M. anisopliae and L. saksenae were found to be more persistent (up to 45th DAI), while B. bassiana and L. lecanii persisted only up to 30 DAI. Soil samples revealed the presence of B. bassiana, M. anisopliae and L. saksenae up to 15th, 30th and 45th DAI respectively. L. lecanii was not found to colonise soil. Grain samples in rice and bloom samples in cowpea did not reveal the presence of any endophytes. In cowpea, several natural endophytes were found to be stumped upon in different parts, which included four fungi and two bacteria. Apart from this a fungal bacterial association, Fusarium + Ebc 3 (unidentified bacterium) was found to be a dominant endophyte. The bacterium Rhizobium mayense isolated from all plant parts was the most dominant endophyte. The other endophytes isolated were the fungi, Cladosporium sp., Clonostachys rosea, Chaetomium globosum and Cerrena sp. and the bacterium Enterobacter cloacae. Rice plants inoculated by seed soaking, with the conidial suspensions of B. bassiana and M. anisopliae @ 108 spores ml-1 and L. saksenae @ 108 spores mL-1 reflected 28.79, 27.17 and 29.99 per cent increase height, 47.71, 44.75 and 47.92 per cent increase in biomass and 37.73, 36.97 and 39.89 per cent increase in grain yield, the highest values being those of L. saksenae and lowest being those of M. anisopliae. Incidence of rice bug assessed in terms of percentage of chaffy grains per panicle was significantly less in L. saksenae (14.21), while in B. bassiana it was 20.48 and in M. anisopliae, 21.61. There was no disease incidence in treated as well as control plants. It is concluded that B. bassiana, M. anisopliae and L. saksenae has endophytic association with rice and cowpea and L. saksenae is a strong endophyte.
Open Access
Augmentation of pollination in culinary melon (Cucumis melo var. acidulus L. Naudin) with Indian bee (Apis cerana indica Fab.)
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2019) Aneetta, M R; KAU; Amritha, V S
The present study entitled ‘Augmentation of pollination in culinary melon (Cucumis melo var. acidulus L. Naudin) with Indian bee (Apis cerana indica Fab)’ was conducted at Department of Agricultural Entomology, College of Agriculture, Vellayani and at farmers field, Thiruvananthapuram during 2017 to 2019. The objectives were to study the foraging behaviour of A. c. indica and to standardise the number of bee hives required for yield enhancement in culinary melon. Preliminary observations on pollinator diversity and on relative abundance of insects were carried out for assessing the dominant pollinator and to study its foraging behaviour. These observations were made at different time periods of the day (0600–0700 h, 1000–1100 h, 1400–1500 h, 1700–1800 h) at weekly intervals during peak flowering stage of plant. The floral biology of culinary melon was also studied to assess plant to pollinator relation. Culinary melon was raised in an area of 1 acre during February to April, 2019 for estimating the number of hives required per hectare for optimum pollination. For the same, an Indian bee hive with six frame bee strength was installed at the centre of plot at 10 per cent flowering. Four radial distances (T1- 10 m, T2- 20 m, T3- 30 m and T4- 40 m) from bee hive were the treatments and four plants each at different distances were considered as replications. The statistical frame work, CRD was followed for the experiment and control plot without bee hive was also maintained to compare the yield difference due to augmented pollination. Studies on pollinator diversity revealed that the pollinators or flower visitors of culinary melon alone comprised of 14 insect species. The common pollinators observed were A. c. indica, Ceratina hieroglyphica, Braunasis sp., C. binghami, Tetragoula travancorica, Lampides boeticus, Aulacophora foveicollis, Luperomorpha vittata, and Camponotus sp. Maximum number of pollinators was recorded during 1000-1100 h with A. c. indica as the dominant pollinator (12.87 bees m-2 in 5 minute duration) in terms of relative abundance. Observations on foraging behaviour of dominant pollinator, A. c. indica indicated that they were nectar foragers with their peak activity during 1000 to 1100 h. The bees commenced foraging on 0700 h and ceased activity on 1800 h, thus rendering eleven hours of foraging time. Maximum foraging rate was 14.17 flowers min.-1 while foraging intensity was 1.60 bees m-2 min.-1. Minimum time spent by bees was recorded as 2.37 sec. on male flowers and 12.07 sec. on female flowers. All bees were alighting directly on stigma and hence regarded as top workers. Studies on floral biology of culinary melon revealed that female flowers were receptive only for one day. Length of stamen (0.45 cm) and proboscis of bees (0.49 cm) were almost same which enabled top working by bees and thereby enhanced pollination through the pollen adhered on the bifid hairs of bees. . For standardising the requirement of bee hives ha-1, yield parameters and foraging intensity were recorded at varying distance. Significantly high foraging intensity and yield parameters were recorded at 10 m distance (fruit set- 75.44%, fruit weight- 0.75 kg) which was immediately followed by 20 and 30 m, which were on par. Economic analysis using B:C revealed that both treatments 10 m (B:C-2.7) and 30 m (B:C-2.5) were economically feasible. Considering the economic and technical feasibility, 30 m was selected as an effective radial distance for adequate bee pollination based on which the number of hives required per ha was estimated as four. Plants at this effective distance recorded significantly higher (p < 0.05) yield parameters, both quantitatively and qualitatively (fruit set- 66.62 %, fruit weight- 0.55 kg) compared to that of plots without hives. Thus, a yield increase of 57.50 per cent was obtained from the plot with bee hive. Deformed fruits were recorded least in augmented plots (39.00 %) than the control plot (54.91 %). Thus the present study indicated that four A. c. indica colonies with six frame bee strength were required for adequate pollination of culinary melon in 1 ha. The peak foraging activity was observed during 1000 to 1100 h with a foraging rate of 14.17 flowers min.-1. Augmented pollination resulted in increased yield both in terms of the quantitative and qualitative parameters, with 57.50 per cent yield enhancement over the control plants.
Open Access
Insecticide mixtures for the management sucking pest complex in chilli
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2019) Anju Viswanathan, K; KAU; Ambily Paul
A study on "Insecticide mixtures for the management of sucking pest complex in chilli" was undertaken at College of Agriculture, Vellayani and farmers field at Kalliyoor during 2018 October to 2019 January. The objectives were to evaluate the efficacy of insecticide mixtures against sucking pest complex in chilli and to study the pesticide residues in chilli fruits. Major pests recorded during the study include white fly, Aleurothrixus trachoides Back, thrips, Scirtothrips dorsalis Hoods, mite, Polyphagotarsonemus latus Banks and aphid. Aphis gossypii Glover. The laboratory experiment was laid out in CRD to study the efficacy of insecticide mixmres viz., thiamethoxam 12.6 % + lambda cyhalothrin 9.5 % ZC @ 33 + 15.75 g a.i ha"', beta cyfluthrin 8.91% + imidacloprid 19.81 % CD @ 15.75 + 36.75 g a.i ha"', flubendiamide 19.92% + thiacloprid 19.92 % SC @ 48 + 48 g a.i ha"', fipronil 40% + imidacloprid 40% WG @ 175 + 175 g a.i ha"', spiromesifen 22.9% SC + thiamethoxam 25 % WG (hand mixed) (1:1) @ 96 + 50 g a.i ha"' along with two positive controls T6- spiromesifen 22.9% SC @ 96 g a.i ha"'and thiamethoxam 25 % WG @ 50 g a.i ha"' against pests of chilli. Results of the laboratory screening revealed that fipronil 40% + imidacloprid 40% WG @ 175 + 175 g a.i ha"' was the effective treatment in managing all sucking pests, in which whiteflies, thrips, mites and aphids were not present on seventh day after spraying. This was followed by beta cyfluthrin 8.91% + imidacloprid 19.81 % OD @ 15.75 + 36.75 g a.i ha"' and thiamethoxam 25 % WG @ 50 g a.i ha"'. No mite population was observed in spiromesifen 22.9 SC @ 96 g a.i ha"' treated plants from second day after application. The insecticide mixtures / insecticides selected for the field studies were fipronil 40% + imidacloprid 40% WG @ 175 + 175 g a.i ha"', beta cyfluthrin 8.91% + imidacloprid 19.81 % OD @ 15.75 + 36.75 g a.i ha"', spiromesifen 22.9% SC @ 96 g a.i ha"' and thiamethoxam 25 % WG @ 50 g a.i ha"' by considering their effectiveness in managing sucking pests under laboratory conditions. The results of field evaluation revealed that less incidence of whiteflies was observed on fipronil 40% + imidacloprid 40% WG @ 175 + 175 g a.i ha"' (0.43 leaf') treated plants on seventh day after spraying followed by beta cyfluthrin 8.91% + imidacloprid 19.81 % OD @ 15.75 + 36.75 g a.i ha-'(0.60 leaf ') and thiamethoxam 25 % WG @ 50 g a.i ha"' (2.23 leaf'). No population of thrips was observed in plants treated with fipronil 40% + imidacloprid 40% WG @ 175 + 175 g a.i ha"' on tenth day after spraying followed by beta cyfluthrin 8.91% + imidacloprid 19.81 % OD @ 15.75 + 36.75 g a.i ha-'(1.30 leaf'). Spiromesifen 22.9% SC @ 96 g a.i ha"' showed superiority over other treatments, in checking the population of mites, P. latus and no mites were observed on plants treated with spiromesifen 22.9% SC @ 96 g a.i ha"' from seventh day after spraying followed by fipronil 40% + imidacloprid 40% WG @ 175 + 175 g a.i ha"' (1.63 leaf') and beta cyfluthrin 8.91% + imidacloprid 19.81 % OD @ 15.75 + 36.75 g a.i ha"' (2.30 leaf'). Spiromesifen 22.9% SC @ 96 g a.i ha"' found to be safe to natural enemies as compared to other treatments. Number of chilli aphids, A. gossypii was lower in fipronil 40% + imidacloprid 40% WG @ 175 + 175 g a.i ha"' (0.52 leaf' ) treated plants followed by beta cyfluthrin 8.91% + imidacloprid 19.81 % OD @ 15.75 + 36.75 g a.i ha"'(0.60 leaf') after seven days of spraying. Dissipation of residues of these effective insecticides was studied by analysing the chilli fruits collected at 0, 1, 3, 5, 7, 10, 15 and 30 days after treatment and the results showed that in fipronil 40% + imidacloprid 40% WG sprayed fruit, fipronil dissipated within two hours of spraying and imidacloprid dissipated in three days. Beta cyfluthrin £uid imidacloprid in beta cyfluthrin 8.91% + imidacloprid 19.81 % OD mixture dissipated within fifteen and seven days respectively. The risk assessment study also proved the safety of the insecticide mixtures. The results of the present study revealed that spraying of fipronil 40% + imidacloprid 40% WG @ 175 + 175 g a.i ha"' or beta cyfluthrin 8.91% + imidacloprid 19.81 % OD @ 15.75 + 36.75 g a.i ha"' could effectively manage pest complex in chilli with minimal risk to end users.

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