Browsing by Author "Ambily Paul"

Now showing 1 - 14 of 14

Bio-ecology of coconut eriophyid mite, aceria guerreronis keifer and yield loss due to its infestation on popular coconut cultivars
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2001) Ambily Paul; Thomas Biju Mathew
Studies were conducted to understand the biology, ecology, population dynamics and rr .te-host interactions of A. guerreronis and to assess the yield loss on popular cultivars of coconut as influenced by nut characters and weather parameters. An abstract of the work done and the results are given below. Biology of A. guerreronis was studied under both laboratory and field conditions. The study indicated that a total period of 9.8 days was required for completing one generation under laboratory condition. Population dynamics of A. guerreronis in young buttons of susceptible and tolerant palms of variety WeT and Komadan was studied from February 2000 to January 2001. Population of mites under each tepal was counted by using cello tape embedding method. The results revealed that the population was the highest in nuts sampled from fifth bunch followed by fourth and sixth bunches in both susceptible and tolerant palms. The present study indicated that age of developing nut was the most critical factor in the study of population dynamics. Monthly mean population of A. guerreronis was correlated with weather parameters viz., temperature, relative humidity and rainfall prevailed during the time of sampling, probable time of mite entry and the total duration of critical age of the bunch. The results indicated that the relative humidity prevailed at the probable time ofmite entry alone had a positive correlation with population in the susceptible type of Ko mad an. The length to circumference ratio of young nuts and its influence on mite injury was observed. The results showed that round nuts having a length to circumference ratio of 1 :1.90 to 1 :2.29 suffered less damage. The study gave an indication that elongated nuts were more susceptible to mite attack than round ones. The expansion of feeding scar on coconut husk due to mite injury in relation to growth of nuts was studied in young nuts with different degree of injury in terms of number of triangular lesions. The study indicated that the age of buttons / nuts at which the colonization started w~ the most critical factor in deciding whether the nut will finally become economically damaged (category 4 and 5) or not. Yield loss studies were carried out from the nuts obtained from ten consecutive harvests by categorizing them into five damaged categories and the yield loss was calculated by deducting actual yield from potential yield. No significant variation was observed among the five varieties studied, viz. WeT, Komadan, T X YD, Laccadive Ordinary and Dwarf Orange Yield loss in terms of reduction in weight ofcopra ranged from 11 to 39 percentage and reduction in weight of husk ranged from 12 to 40 percentage. Additional labour requirement for de husking infested nuts was studied in a separate experiment. Study revealed that an extra time of 25.05 to 41.75 minutes was required to dehusk 100 damaged nuts over healthy nuts. Another experiment was conducted to assess the effect of mite injury on the quality and quantity of fibre and coir. Husk obtained from fifty harvested nuts representing the damage categories 1 to 5 were subjected to natural retting practices. Fibre obtained from nuts coming under damage category 4 and 5 resulted in 47-53 per cent reduction in length.
Dissipation and risk assessment of select insecticides used for pest management in cabbage and cauliflower
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2018) Anju Padmanabhan; Ambily Paul
Documentation and management of oriental fruit fly, Bactrocera Spp.(Diptera:Tephritidae) in banana
(Department of Agricultural Entomology, College of Agriculture , Vellayani, 2022-03-16) Remya , S R.; Ambily Paul
The study on “Documentation and management of Oriental fruit fly, Bactrocera spp. (Diptera: Tephritidae) in banana” was carried out at the Department of Agricultural Entomology, College of Agriculture, Vellayani during 2019 to 2021. The objectives were to document the species complex and cultivar preference of Bactrocera spp. infesting banana and to find out the effective management practices against them. Purposive survey conducted among 20 farmers each of two districts viz., Thiruvananthapuram and Kollam revealed that Palayankodan was the most susceptible cultivar to the fruit flies followed by Red banana. High TSS (17.80°Brix) of Palayankodan favoured the infestation. Fruit fly species infesting the banana cultivars viz., Palayankodan, Red banana and Nendran was identified as Bactrocera dorsalis Hendel. Bactrocera caryeae Kapoor was reported along with B. dorsalis from guava. Studies on the biology of B.dorsalis in banana under laboratory condition revealed that egg, larva, pupa and total life cycle ranged from 1-3, 7-12, 7-10 and 51- 58 days respectively. Morphometric studies revealed that the average length and breadth of eggs, full-grown maggots and pupae were 2.52±0.10 and 0.95±0.04 mm, 6.38±2.67 and 1.26±0.24 mm, 5.58±0.29 and 2.47±0.08 mm respectively. The investigation on the assessment of critical stage of banana susceptible to fruit flies was studied on Palayankodan fruits at different ripening maturity viz., under- mature, mature and over-mature. The critical stage of infestation by fruit flies was identified as “over mature”. Significantly higher number of oviposition punctures (13.30) and maggots (12.10) per banana finger was observed in “over-mature” fruit. Though oviposition punctures was noticed in mature (6.90) and under mature (3.20) fruits, no maggots were emerged from them. The tannin content in peel and pulp of Palayankodan fruits at different ripening maturity was estimated using folin-denis method to determine the defensive role played by tannin in the prevention of B.dorsalis infestation. The highest tannin level was found on both peel (235.29 mg g-1 DW) and pulp (265.62 mg g-1 DW) of under mature fruits. In over mature fruits, both peel (120.08 mg g-1 DW) and pulp (98.88 mg g-1 DW) recorded less tannin content which supported oviposition and growth of maggots. Laboratory experiment was laid out in CRD to study the efficacy of treatments against B. dorsalis on Palayankodan immediately after the harvest. Among various treatments, quinalphos 25 EC 0.05% was found to be the best treatment in reducing fruit fly infestation in banana followed by spinosad 45 EC 0.02%, azadirachtin 0.03% and salicylic acid 2mM. The oviposition deterrence recorded was significantly higher in quinalphos 25 EC (97.03%) followed by spinosad 45 EC (93.97%), azadirachtin (80.14%) and salicylic acid 2mM (63.44%). Presence of residues of quinalphos (0.021 mg kg -1) and spinosad (0.069 mg kg -1) in banana at the time of harvest was above MRL (0.01 mg kg-1), hence the next effective treatment, azadirachtin (0.03%) which was on par with Spinosad could be recommeded after harvest for the management of fruit flies in banana. The study could be concluded that the species of fruit fly infesting banana cultivars was identified as B. dorsalis and Palayankodan is the preferred cultivar and the critical stage of infestation by B. dorsalis was “overmature”. Post harvest spraying of azadirachtin (0.03%) was found to be effective and safe for the management of fruit flies, B. dorsalis in banana.
Incidence and management of sucking pests on gerbera under protected cultivation
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2020) Paladugu Yasavi; Ambily Paul
Insecticide mixtures for the management of pest complex in cowpea
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2018) Banka Kanda Kishore Reddy; Ambily Paul
Insecticide mixtures for the management sucking pest complex in chilli
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2019) Anju Viswanathan, K; Ambily Paul
Insecticide resisitance in cowpea aphid, Aphis craccivora (koch) and its management
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2018) Jangam Hampaiah; Ambily Paul
Insecticide resistance in spiralling whitefly,aleurodicus dispersus russell(hemiptera:aleyrodidae) and its management
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2019) Aura Senson; Ambily Paul
Insecticide resistance in spotted pod borer, Maruca vitrata (Fabricius) on vegetable cowpea and its management
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2014) Pattapu Sreelakshmi; Ambily Paul
A study on “Insecticide resistance in spotted pod borer Maruca vitrata (Fabricius) on vegetable cowpea and its management” was undertaken at College of Agriculture, Vellayani and in the farmer’s field at Kalliyoor and Venganoor panchayaths during January, 2013 to May, 2014. The main objectives were to assess the insecticide resistance in field population of spotted pod borer, M. vitrata, evaluate the efficacy of new generation insecticides against the resistant population and determine the harvest time residues in cowpea pods. A preliminary survey conducted among cowpea growers in Kalliyoor and Venganoor panchayaths of Thiruvananthapuram district revealed control failures in the field population of spotted pod borer due to the continuous application of a single insecticide like chlorpyriphos or lambda cyhalothrin. The survey data served as the benchmark for further studies on the insecticide resistance in M. vitrata. Bioassay was carried out in CRD to assess insecticide resistance in populations of M.vitrata collected from three different locations (location I- field with no previous history of pesticide application, location II- field where less control failures and location III- field where more control failures) using two chemicals viz. chlorpyriphos and lambda-cyhalothrin at different doses. Results revealed that population collected from location-I was found to be susceptible for both the chemicals with resistance ratio-1, population collected from location-II to be moderately resistant with a resistant ratio of 2.28 and 2.38 and population from location-III to be resistant with resistance ratios of 2.93 and 7.94 for chlorpyriphos and lambda-cyhalothrin respectively. Laboratory experiments conducted to evaluate the efficacy of new generation insecticides viz. novaluron - 0.015 per cent, flubendiamide - 0.01 per cent, spinosad - 0.015 per cent, emamectin benzoate - 0.002 per cent, indoxacarb 14.5 per cent + acetamiprid 7.7 per cent SC- 0.09 per cent, acephate 50 per cent + imidacloprid 1.8 per cent SP - 0.20 per cent, chlorantraniliprole - 0.03 per cent, indoxacarb - 0.10 per cent and chlorpyriphos - 0.05 per cent (as check) against the resistant population of M.vitrata revealed that the per cent mortality of the second instar larvae treated with insecticides viz. emamectin benzoate, indoxacarb+acetamiprid and spinosad were 97.28, 97.28 and 90.90 per cent respectively after 6 hours of treatment. Hence, these insecticides were selected for further field trials against the resistant population of M .vitrata. The field experiment was conducted in RBD with four treatments viz. emamectin benzoate 0.002 per cent, indoxacarb+acetamiprid 0.09 per cent and spinosad 0.015 per cent including control against the resistant population of M.vitrata. Application of emamectin benzoate, indoxacarb + acetamiprid and spinosad resulted in a reduction of 81-100, 64-100 and 69.96 - 99.6 per cent respectively in the case of flower infestation and 83 -100, 23.38 - 98.40 and 55.26 – 100 per cent respectively in case of pod infestation. Harvest time residue estimation done on 7th day after the application of insecticides showed the residues below the quantitative limit of 0.05 mg kg-1 revealing its safety for consumption. The study could indicate the development of insecticide resistance in the field population of M.vitrata. On the basis of the present study it could be concluded that spraying of emamectin benzoate @ 10 g ai ha-1 or indoxacarb + acetamiprid @100 g ai ha-1 or spinosad @ 75 g ai ha-1 could effectively manage the resistant population of M. vitrata in cowpea. This study forms a maiden attempt in assessing the extent of insecticide resistance development in the populations of M. vitrata in Kerala. Further studies have to be taken up to develop and popularize an Insecticide Resistance Management (IRM) strategy against this devastating pest of cowpea.
Management of pesticide residues in grapes
(Department of Entomology, College of Agriculture, Vellayani, 2024-12-16) Lirin Sharath, B; Ambily Paul
The study on ‘Management of pesticide residues in grapes’ was carried out at Pesticide Residue Research and Analytical Laboratory (PRRAL), Department of Entomology, College of Agriculture, Vellayani and farmers field, Theni district of Tamil Nadu during the period 2022-24. The main objectives of the study were to monitor the pesticide residues in grapes, to evaluate the decontamination methods and to assess the effect of processing on the removal of pesticide residues in grapes. Monitoring studies to find out pesticide residues in farm gate samples were conducted at Theni district of Tamil Nadu and market samples were collected from various districts of Kerala. Monitoring studies revealed that 100 per cent of farm gate and market samples of grapes were detected with pesticide residues. Out of 27 pesticides detected, 17 were insecticides and 10 were fungicides. The detected insecticides include eight organophosphates, four neonicotinoids, two synthetic pyrethroids, one each from diamide, tetramic acid derivative and IGR. Among the processed products, 37.50 per cent of ball grapes and raisins samples were found to be contaminated. No residues were detected from squash and wine samples. Buprofezin, malathion, carbendazim, metalaxyl, tebuconazole and pyraclostrobin, difenoconazole and penconazole were the pesticides detected below FSSAI MRL. A laboratory experiment was conducted to evaluate the effectiveness of various decontamination methods in removing pesticide residues from grapes. Organically grown grape vines at fruiting stage were selected from Cumbum, Theni district of Tamil Nadu. The selected vines with fruits were uniformly applied with a mixture of 11 pesticides (at double the recommended dose) selected based on data obtained from monitoring studies. Grapes were harvested 48 hours after spraying, subjected to decontamination treatments and analysed for residues. The result showed that soaking grapes in 2% sodium carbonate solution for 10 min followed by washing two times with water was effective in removal of pesticide residues (43.15-84.71 %). The second superior treatment was soaking grapes in lukewarm water (45.26-79.33 %). In radiation treatment, treated grapes were exposed to different levels of gamma radiation 0.50, 1.00 and 1.50 kGy and two different UV radiations - UV A (365 nm) and UV B (312 nm) at 5 and 10 min each. It was observed that gamma radiation 1 kGy was 98 effective in removing pesticide residues by 46.67-83.25 per cent followed by gamma radiation 0.5 kGy 19.28-66.95 per cent. Treated grape samples were processed into squash, wine, ball grapes and raisins following the standard protocol and the extent of removal of pesticide residues due to processing was calculated. The results showed that processing of grapes into wine had maximum removal of pesticide residues 56.55-100 per cent followed by ball grapes (44.63-91.99 %). Sensory acceptability studies were conducted for sensory parameters like appearance, colour, texture, taste, aroma and overall acceptability of the decontaminated and processed products of grapes. It was carried out by a panel of 30 judges of different age group and they evaluated using hedonic scale ratings using Kendall’s W test. Similar ratings were assigned to all the parameters by the evaluators for both decontaminated and processed products of grapes. To conclude, monitoring studies of grapes revealed that 100 per cent of farm gate and market samples, as well as 37.50 per cent of processed products, contained pesticide residues. Decontamination studies showed that soaking grapes in 2% sodium carbonate solution followed by soaking in lukewarm water for 10 min, resulted in the highest removal of pesticide residues. Among radiation treatments, gamma radiation at 1 kGy was found to be an effective method for eliminating pesticide residues from grapes. Among processing methods, wine making showed the maximum removal of pesticide residues, followed by ball grapes.
Management of pests of cowpea and salad cucumber in polyhouse
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2016) Thamilarasi, N; Ambily Paul
A study on “Management of pests of cowpea and salad cucumber in polyhouse” was undertaken in polyhouses of Thiruvananthapuram district and College of Agriculture, Vellayani during January 2015 to May 2016. The main objectives were to document the pests and natural enemies on cowpea and salad cucumber in polyhouses and to evaluate the efficacy of new generation insecticides against the major pests. A purposive survey was conducted in 20 polyhouses in Thiruvananthapuram district to document the pests and natural enemies. Sucking pests viz., pea aphid, Aphis craccivora (Koch), mealy bug, Ferrisia virgata (Cockerell), pod bug, Riptortus pedestris (Fabricius), fulgorid bug, Eurybrachys tomentosa (Fabricius), thrips, Ayyaria chaetophora (Karny), spotted red mite, Tetranychus truncatus (Ehara) and leaf feeders viz., pod borer, Lampides boeticus (Linnaeus), tobacco caterpillar, Spodoptera litura (Fabricius), leaf beetle Pagria flavopustulata (Baly), American serpentine leaf miner, Liriomyza trifolii (Burgess) are the pests associated with cowpea. New pests viz., tortrycid larvae, leaf miner and girdle beetle, Oberiopsis brevis (Gahan) were reported from cowpea under polyhouse. Sucking pests viz., green peach aphid, Myzus persicae (Sulzer), mealy bug, Ferrisia virgata (Cockerell), thrips, Astrothrips tumiceps (Karny), Thrips hawaiiensis (Morgan), Frankliniella schultzei (Trybom) spotted red mite, Tetranychus sp, and leaf feeders viz., pumpkin caterpillar, Diaphania indica (Saunders), American serpentine leaf miner, Liriomyza trifolii (Burgess) are associated with salad cucumber under polyhouse conditions. The natural enemies observed were coccinellids, syrphids and spiders viz., Oxyopes javanus (Thorell), Oxyopes sunandae (Tikader) and Argiope pulchella (Thorell) from both cowpea and salad cucumber. The data on preliminary survey revealed that both sucking and leaf feeder pests caused significant damage to cowpea and salad cucumber inside polyhouse.Experiments were carried out in CRD to evaluate the efficacy of new generation insecticides viz. acetamiprid 0.10 g L -1 , imidacloprid 0.20 mL L -1 , thiamethoxam 0.30 g L -1 , thiacloprid 0.25 mL L -1 , dimethoate 1.50 mL L -1 against sucking insects viz., A. craccivora, M. persicae and R. pedestris and acaricides viz., spiromesifen 0.80 mL L -1 , fenpyroximate 0.60 mL L -1 , dimethoate 1.50 mL L -1 against Tetranychus sp. Spinosad 0.30 mL L -1 , chlorantraniliprole 0.30 mL L -1 , flubendiamide 0.10 mL L -1 , indoxacarb 1.00 mL L -1 , quinalphos 3.00 mL L -1 were tested against leaf feeders viz., L. trifolii and D. indica. Evaluating the efficacy of new generation insecticides, thiamethoxam 0.30 g L -1 and imidacloprid 0.20 mL L -1 were found to be effective against sucking pests which reduced the mean population of A. craccivora to 7.33 and 12.67 aphids plant -1 respectively and M. persicae to 4.67 and 11.67 aphids plant -1 respectively after 15 days of treatment. However, thiamethoxam 0.30 g L -1 and imidacloprid 0.20 mL L -1 were found to be equally effective in managing R. pedestris which reduced the population to 0.20 bugs plant -1 . Spiromesifen was recorded to be the best by reducing the population to 10.50 and 16.25 mite plant -1 in cowpea and salad cucumber respectively. Chlorantraniliprole 0.30 mL L -1 and spinosad 0.30 mL L -1 reduced the population of leaf miner to 0.60 and 0.40 larvae plant -1 in cowpea respectively and 0.20 and 0.60 larvae plant -1 in salad cucumber respectively and no larvae of D. indica were recorded in chlorantraniliprole 0.30 mL L -1 and flubendiamide 0.10 mL L -1 treated salad cucumber 15 days after spraying. The dissipation (persistence/ degradation of residues) study showed that the promising insecticide thiamethoxam 0.30 mL L -1 persisted upto 7 and 5 days in cowpea and salad cucumber respectively and imidacloprid 0.20 mL L -1 persisted upto one day in both cowpea and salad cucumber and spiromesifen 0.80 mL L -1 persisted upto 7 and 5 days in cowpea and salad cucumber respectively. Chlorantraniliprole 0.30 mL L -1 and spinosad 0.30 mL L -1 persisted upto 5 and 7 days in cowpea and 3 days each in salad cucumber respectively.From the present study it is concluded that both sucking pests and leaf feeders are causing significant damage in cowpea and salad cucumber under polyhouse conditions. Application of thiamethoxam 0.30 g L -1 and imidacloprid 0.20 mL L -1 effectively manage the sucking pests viz., A. craccivora, M. persicae and R. pedestris. Spiromesifen 0.80 mL L -1 was found to be the best to manage the Tetranychus sp. Chlorantraniliprole 0.30 mL L -1 and spinosad 0.30 mL L -1 were found to be effective in managing leaf feeders in both cowpea and salad cucumber. A harvest interval of 5 to 7 days should be given to ensure the safety of the produce from the polyhouse to the end users.
Management of phytophagous ants in vegetable crops under homestead cultivation
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2023-02-17) Kavya, K T; Ambily Paul
The study entitled ‘Management of phytophagous ants in vegetable crops under homestead cultivation’ was carried out at Department of Agricultural Entomology, College of Agriculture, Vellayani during the period 2021-2022. The main objectives of the study were to document the phytophagous ants infesting vegetables, to assess the extent of damage and to develop effective management practices against them. Fourteen phytophagous ant species were identified from various vegetable crops viz., Myrmicaria brunnea Saunders from cowpea, Anoplolepis gracilipes Smith, Meranoplus bicolor Guerin-Meneville, Camponotus mendax Forel, Camponotus rufoglaucus Jerdon, Tetramorium smithi Mayr, Carebara diversa Jerdon, Solenopsis geminata Fabricius, Trichomyrmex destructor Jerdon, Diacamma assamense Emery, Monomorium sagei Forel, Nylanderia yerburyi Forel, Tapinoma melanocephalum Fabricius from okra and Camponotus compressus Fabricius from brinjal during the purposive survey conducted among ten farmers each of two districts viz., Kozhikode and Thiruvananthapuram. Study revealed that okra was the most preferred crop with 35 per cent infestation followed by brinjal (18.18%) and cowpea (14.28%). Based on the results of the survey, C. diversa, S. geminata and T. destructor were identified as the most destructive phytophagous ant species owing to their regular feeding behavior and preference for both flowers and fruits. From the study on assessment of extent of damage, the most preferred part in okra for attack of S. geminata was flower bud (11.82%), followed by flower (9.56%) and fruit (6.67%) respectively. Flowerbuds, fruits and flowers were equally susceptible to the attack of T. destructor, while in case of C. diversa preference was for fruits (6.45%) rather than flowers (3.54%) and flower buds (4.34%). Biochemical analysis was conducted to quantify the sugars (glucose, fructose and sucrose) in different plant parts of okra viz., flowers, fruits, leaves, stem and tender shoots which revealed that concentration of all the sugars was the highest in fruits followed by leaves and flowers. Field experiment to test the attractiveness of traps proved that greater attractiveness was shown towards sugar based liquid baits. Accordingly, more number of ants were attracted towards sugar 25% + boric acid (0.5%) (7.60), sugar 25% + thiamethoxam(0.0001%) (7.63) and sugar 25% (control)). In the laboratory experiment to test the efficacy of traps, the highest ant mortality was recorded in sugar + rava + fipronil (1:1:0.3) where 100 per cent mortality was obtained in 24 h. In case of sugar 25% + boric acid (0.5%) and sugar 25% + thiamethoxam 0.0001%, a steady hike in mortality due to delayed action of toxic materials in which 65.11 and 52.58 per cent mortality was recorded respectively on 19th day after placement of traps. In field experiment on management of phytophagous ants by the application of various treatments, up to fifth day after treatment, no phytophagous ants was observed in okra plants treated with ethion 40% + cypermethrin 5% EC. Ant population on plants treated with Neem oil + garlic emulsion, turmeric powder, lemon garlic extract, talc based formulation of B.bassiana, H. indica were 77.55, 72.05, 69.56, 65.54 and 82.91 respectively and were significantly on par. Harvest time residues of insecticides (ethion, cypermethrin, fipronil, thiamethoxam) applied in different treatments in okra fruits were less than Limit of Quantification (LOQ for ethion and cypermethrin was 0.05 mg kg-1 and for fipronil and thiamethoxam LOQ was 0.01mg kg-1 ). To conclude, fourteen phytophagous ant species were identified during the survey conducted at Kozhikode and Thiruvananthapuram districts. The most preferred crop for phytophagous ants was okra and the most destructive phytophagous ant species on vegetables were identified as C. diversa, S. geminata and T. destructor. The most susceptible stage to S. geminata attack was flower bud (11.82 %), while in T. destructor, flower bud, flower and fruit were equally susceptible to attack. In case of C. diversa, the most susceptible stage to attack was fruit (6.45% ). In the laboratory experiment on ant mortality the best results were obtained in sugar + rava + fipronil (1:1:0.3) with 100 per cent mortality followed by sugar 25% + boric acid(0.5%) and sugar 25% + thiamethoxam (0.0001%) with 65.11 per cent and 52.58 per cent mortality respectively. In the field experiment on testing the attractiveness of traps greater preference of ants was observed in sugar 25% + boric acid (0.5 %) and sugar 25% + thiamethoxam (0.0001%). In field experiment on management of phytophagous ants by the application of various treatments, up to fifth day after treatment, no phytophagous ants was observed in okra plants treated with ethion 40% + cypermethrin 5% EC.
Pesticide residue management in harvested capsules of small cardamom
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2020) Aparna Joseph; Ambily Paul
Population dynamics, intensity of damage and management of the coreid bug, paradasynus rostratus dist.
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2006) Ambily Paul; Nandakumar, C
Experiments were conducted to study the influence of alternate hosts on the population dynamics of the coreid bug, Paradasynus rostratus Dist. and consequent damage to coconut and to evolve an eco-friendly management strategy to the pest. An abstract of the work done and the results are given below. A survey conducted in Thiruvananthapuram district to study the incidence and intensity of coreid bug infestation on coconut revealed that the infestation was the highest in the coastal region. The incidence was lower in the upland and midland regions. Among the variety of crops seen in the coconut based homesteads, guava, cashew, cocoa and neem were recorded as potential hosts of the pest. Studies on the influence of alternate hosts on the population build up of coreid bug revealed that the alternate hosts were a major determinant in the extent of infestation of coreid bug on coconut. The pest multiplied on the alternate hosts during flushing, flowering and fruit formation stages of the crops and subsequently shifted to the base crop, coconut in multiple cropping systems. The changes in size and yield parameters of nut due to the infestation of P.rostratus were assessed. Nuts with negligible damage (category II) did not show any significant difference in nut shape, nut characters, copra and oil content. Significant reduction in copra and oil was observed in moderately (category IV) and , heavily (category V) damaged nuts. The endosperm was not at all formed in severely damaged (category VI) nuts. The changes in the biochemical constituents of coconut buttons due to feeding of coreid bug were studied. The phenol content in young infested nuts recorded an increase compared to healthy nuts. A progressive reduction in starch and fibre content of young nuts was obtained with increase in degree of infestation The study on the effect of infestation of P.rostratus on germination and vigour of seedlings revealed that though all the nuts in damage category II (negligible damage) to IV (moderate damage) germinated within six months, only seedlings from nuts with negligible damage (category II) had the qualities of good seedlings. The antifeedant effect of neem based botanicals and efficacy of synthetic chemical pesticides were evaluated against coreid bug. Among the botanical and chemical pesticides, neem seed oil- garlic emulsion 2 per cent and profenophos 0.05 per cent proved most effective against the coreid bug. A field experiment was conducted to evaluate the effect of selected treatments on alternate hosts for control of coreid bug in coconut. The study revealed that the combined application of neem seed oil- garlic emulsion 2 per cent + profenophos 0.025 per cent was the most effective in reducing the extent of coreid bug infestation in the surrounding coconut palms. The present study could establish the role of alternate hosts on the population buildup of coreid bug. Plant protection operations in alternate hosts against coreid bug are more effective, economical and viable options compared to those in coconut. Based on the results of the study, a package involving regular monitoring of the alternate hosts in the homesteads, removal and destruction of the egg masses and early instars of the pest and giving a need based spray with an insecticide formulation like neem oil- garlic emulsion 2 per cent + profenophos 0.025 per cent on the alternate host would be a practical and cost effective approach for reducing the damage of P.rostratus on coconut in the homesteads.