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Open Access
Eumolpinae (Coleoptera: Chrysomelidae) of southern India
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2021) Amritha Kumari, S; KAU; Prathapan, K D
The present study entitled “The Eumolpinae (Coleoptera: Chrysomelidae) of southern India” was carried out at Collage of Agriculture, Vellayani from October 2015 to March 2020. The study was designed with the objectives of collection and identification of the eumolpine leaf beetles of south India, preparation of illustrated keys to genera and species with emphasis on the characters of male and female genitalia and documentation of host plants in all possible cases. One thousand five hundred and two specimens from various ecosystems in south India were studied. Hand picking, aspiration, sweep netting and light traps were used to collect eumolpines. Specimens were also procured on loan basis from different institutions in India and abroad. Collected specimens were mounted and labelled. Available ecological and biological information was gathered in all cases. Genitalia was dissected as per standard procedures. Inflation and eversion of endophallus follow Yamasako & Obhayashi (2011). Specimens were identified tentatively based on the available literature and then confirmed by comparing with type specimens or consulting with experts. Measurements were made with a calibrated ocular micrometer and pertinent ratios were worked out. Illustrated keys, descriptions and diagnosis are provided. Male genitalia, including endophallus and female genitalia are described and illustrated. The Afrotropical genus Microeurydemus is newly reported from the Oriental Region. Malegia and Scelolanka are new reports to India. Pagria ingibbosa, P. ceylonica and P. pseudograta are new species records for India. Range of distribution of Basilepta subcostata and Trichochrysea are extended to south India. Tricliona Lefèvre, 1885 new snynonym is a new junior synonym of Bathseba Motschulsky, 1866. Neofidia Strother new name, is proposed as the replacement name for Fidia Baly, 1863, a junior homonym of Fidia Motschulsky, 1861. Bathseba syzygium n. sp. and Pseudostonopa palynophaga n. sp. are described as new to science. Eleven putative new species in the genera Mesocolaspis, Malegia, Microeurydemus, Basilepta, Cleoporus, Dermorhytis, Edistus, Pagria, Scelolanka and Trichochrysea were described. New host plant records include Anacardium occidentale L. (for Fidia kanaraensis), Ixora (for Eurypelta modesta), Aegle marmelos (for Colasposoma downesi), Mallotus atrovirens (for Cleoporus inornatus), Antidesma acidum (for Edistus sp.), Milletia pinnata (for Scelolanka). Bathseba syzygium n. sp. has been reported on Syzygium cumini and Pseudostonopa palynophaga n. sp. has been reported as a pollen feeder of Poaceae. Pagria signata species group warrants further investigations, due to inconsistencies in morphological, genetalic and molecular characters. The eumolpine leaf beetle fauna of south India comprises 146 species placed in 35 genera. Checklist of Eumolpinae of south India is provided. The study treated 53 species under 20 genera. Two new species, 11 putative new species in 10 genera, 12 new host plant records, several new distributional records and new characters of taxonomic value are reported. Nomenclature of many economically important eumolpines are updated.
Open Access
Galerucine leaf beetles (Coleoptera: Chrysomelidae: Galerucinae: Galerucini) of southern India
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2021) Viswajyothi, K; KAU; Prathapan, K D
The study entitled ‘The galerucine leaf beetles (Coleoptera: Chrysomelidae: Galerucinae: Galerucini) of southern India’ was carried out at College of Agriculture, Vellayani during September 2016−April 2021. The study was designed with the objectives of collection and identification of galerucine leaf beetles of southern India; documentation of host plants and other ecological data in all possible cases; preparation of illustrations and descriptions, with emphasis on characters of male and female genitalia; and preparation of an illustrated key to species. The study area encompasses the states of Andhra Pradesh, Karnataka, Kerala, Tamil Nadu and Telangana. Eight hundred and thirty-three specimens belonging to 41 species in 27 genera were studied. Detailed descriptions were prepared, with colour photographs of dorsal, ventral, lateral and anterior habitus as well as diagnostic characters, including male and female genitalia. Additionally, internal sac or endophallus was everted in relevant and possible cases and illustrated. Measurements and proportions are provided. An illustrated key to select genera and species of Galerucini of south India is given. A checklist of known galerucine leaf beetles of south India is provided. Two putative new genera and two putative new species are described and illustrated. A new species Charaea sahyadrica Bezdek and Viswajyothi was published from this study. The habiti of 20 species in colour, male genitalia of 22 species and female genitalia of 24 species are given for the first time. Twenty-seven new host plants, including eleven (40.7%) economically important ones, were recorded. New host plant records are Aulacophora calva on Coccinia grandis (L.) Voigt, Cucumis sativus L. and Cucurbita moschata Duchesne ex Poir. (Cucurbitaceae); A. cincta on Manilkara hexandra (Roxb.) Dubard (Sapotaceae); A. frontalis on Trichosanthes tricuspidata Lour. (Cucurbitaceae); A. impressa on Cucumis sativus L., Cucurbita moschata Duchesne ex Poir. and Trichosanthes cucumerina L. (Cucurbitaceae); A. opacipennis on Momordica charantia L. and Trichosanthes tricuspidata Lour. (Cucurbitaceae); Cassena bengalensis on Mucuna bracteata (L.) DC. (Fabaceae); Erganoides flavicollis on Naravelia ceylanica (L.) DC. (Ranunculaceae) and an unidentified legume (Fabaceae); Galerotella sp. on Cayratia Juss. sp. (Vitaceae); Hoplosaenidea indica on Aphanamixis polystachya (Wall.) R. N. Parker (Meliaceae); Monolepta longitarsis on Piper nigrum L. (Piperaceae) and Spondias pinnata (L. f.) Kurz (Anacardiaceae); Oides affinis on Spermacoce hispida L. and Spermacoce ocymoides Burm.F. (Rubiaceae); Oides flava (Olivier) on Cayratia sp. (Vitaceae); Gallerucida sp. on Cayratia sp.; Sphenoraia hopei on Desmodium triflorum (L.) DC. (Fabaceae) and Myristica fragrans Houtt. (Myristicaceae); Trichomimastra hirsuta on Syzygium cumini (L.) Skeels) (Myrtaceae); Genus 1 on Spatholobus parviflorus (DC.) Kuntze (Fabaceae) and Genus 2 on Aporosa lindleyana (Wight) Baill. (Phyllanthaceae). New distribution records include two new country records and 10 new state records. The new records to India are A. opacipennis in Karnataka and Kerala and A. tibialis in Kerala. The new records to Kerala are A. frontalis; Cassena bengalensis; Erganoides flavicollis; Galerotella simplicicollis; Kanarella unicolor; Liroetes apicicornis; Mimastra alternata; Oides flava (Olivier); Genus 1 and Genus 2. The new records to Karnataka are Aulacophora parambikulamensis; Hoplasoma costatipennis; Mimastracella hirsuta; Sastroides besucheti and Trichomimastra hirsuta. Aulacophora calva is being reported for the first time in Karnataka and Kerala.
Open Access
Lamiinae (Coleoptera: Cerambycidae) of southern India
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2021) Sangamesh, R Hiremath; KAU; Prathapan, K D
The present study entitled “The Lamiinae (Coleoptera: Cerambycidae) of southern India” was carried out at College of Agriculture, Vellayani during 2015 to 2020 with the objectives of collection and identification of the flat faced long-horned beetles (Lamiinae) of southern India, preparation of descriptions and illustrated key to species, with emphasis on characters of male and female genitalia and documentation of host plants in all possible cases. The specimens were collected using different methods viz., hand picking, sweep netting, light traps, jackfruit twig trap and rearing from the infected plant parts. The specimens were processed following the standard procedures. Similarly, dissections, photographs and illustrations were prepared. Details of the specimens examined and the measurements of different body parts including that of male and female genitalia are included under each species. All the species included in the present study were identified using available literature. Taxon descriptions were prepared by considering all the morphological variations and also including the variations of male and female genitalia wherever available. A checklist of the species and illustrated key to the genera documented in the present study are also provided. Present study has generated taxonomic and ecological information on the Lamiinae fauna of south India. Sixty six species belonging to 41 genera of south Indian Lamiinae were studied. Detailed descriptions and illustrations, including that of male and female genitalia, are provided. Species-wise distribution and host plant data are furnished wherever available. Ecological information is also provided for a few of the species. Descriptions of two new species, Miccolamia ferruginea and Notomulciber viraktamathi were published. These include species descriptions, key to Indian species of the respective genera and a discussion on the need for redefinition of the respective subgenera. Description of the male of Monochamus shembaganurensis, with additional information on its distribution, was published. Four new species were recognised, one each belonging to the genera Eunidia and Falsoropica and two of Glenea. New distributional and ecological data are furnished for Acalolepta tenuipes, Agelasta quadrimaculata, Apomecyna saltator, Apriona trilineata, Batocera rufomaculata, Coptops aedificator, Epepeotes uncinatus, Eucomatocera vittata, Eunidia bicolor, Eunidia variegata, Eunidia simplex, Exocentrus (Camptomyne) vittatus, Hirtaeschopalaea albolineata, Macrochenus tigrinus, Nupserha bicolor, Olenecamptus bilobus, Phelipara indica, Sthenias grisator, Sybra praeusta, Thylactus angularis, Zotalemimon posticatum and Zotalemimon procerum. Among the south Indian Lamiinae, Apomecyna saltator, Batocera rufomaculata, Celosterna scabrator, Cleonaria bicolor, Coptops aedificator, Glenea multiguttata, Nupserha bicolor, Olenecamptus bilobus, Sthenias grisator and Sybra praeusta are well known pestiferous species. There are many Lamiinae still awaiting discovery and formal naming. Hence, studies encompassing the different ecozones of the country are sure to add several new species of flat faced longhorned beetles to the Indian fauna. Many species are known only by original descriptions based on a single specimen. Hence, there is an urgent need for intensive studies to generate information on their natural history. Future studies should concentrate on revising and updating the taxonomy of Lamiinae of economic importance so as to develop effective IPM programmes. To promote and facilitate studies on biodiversity and conservation of the native fauna of longhorned beetles, there is an urgent need to digitalize the type specimens of Indian Cerambycidae deposited in several European natural history museums besides developing a database with interactive keys for easy identification. The future taxonomic works on Indian Cerambycidae should also aim for Phylogeny of Indian fauna based on integrative taxonomy.
Open Access
Biotic agents for the management of American serpentine leaf miner, Liriomyza trifolii(Burgess) (Diptera:Agromyzidae)
(Department of agricultural entomology, College of horticulture, Vellanikkara, 2014) Jyothi Sara, Jacob; KAU; Maicykutty P, Mathew
A study on “Biotic agents for the management of American serpentine leaf miner, Liriomyza trifolii (Burgess) (Diptera: Agromyzidae)” was carried out at the Department of Agricultural Entomology, College of Horticulture, K.A.U., Vellanikkara during 2011-2013 with the objectives of collection and identification of indigenous natural enemies and to assess the pathogenicity of the entomopathogens to explore the feasibility of utilizing them for its management. Surveys were conducted in the vegetable fields for the collection and identification of natural enemies associated with L. trifolii in three districts, namely, Thrissur, Ernakulam and Kottayam from January to March, 2011. The surveys revealed the occurrence of nine species of hymenopteran parasitoids. The per cent parasitism varied from 10.96 to 58.99 per cent among the crops surveyed. Three species of eulophids, namely, Cirrospilus acadius Narendran, C. brevicorpus Shafee & Rizvi and Aprostocetus sp. as well as the braconid, Toxares sp. are new reports for India. Among the parasitoids, Closterocerus spp. were the dominant group followed by Chrysonotomyia sp. All parasitoids were solitary, larval endoparasitoids except Toxares sp. which was larval-pupal in nature. One species each of small ants (Formicidae) and a dipteran fly (Dolichopodidae) were observed as predators on L. trifolii. In the study, no entomopathogens were observed from L. trifolii. Considering the level of pesticide consumption in vegetable crops that undermine the potential of insect parasitoids and also that no entomopathogens could be observed during the survey, it was decided to evaluate entomopathogenic nematodes (EPNs) as biocontrol agents against L. trifolii. Isolation of EPNs from 72 soil samples from Thrissur, Ernakulam and Kottayam districts yielded four isolates of Steinernema carpocapsae. Bioefficacy studies carried out on these four isolates along with Steinernema bicornutum and Heterorhabditis indica showed that S. carpocapsae Isolate - 1 had the lowest LC 50 , LC 90 and LT values indicating their higher effectiveness against the maggots of the pest. 50 Pot culture study conducted to compare the potential of S. carpocapsae Isolate - 1 with other treatments showed that azadirachtin 1 EC at 0.005% was the most effective causing 84.51 per cent mortality to the maggots of L. trifolii. This was followed by the foliar application of H. indica at 32 infective juveniles (IJs)/ maggot which caused 18.98 per cent mortality. Application of Beauveria bassiana at 1×10 7 spores/ ml was not effective. In the field evaluation, fipronil 5 SC at 0.002% was found to be the most effective treatment for controlling L. trifolii followed by azadirachtin 1 EC at 0.005%. Compatibility of the IJs of the S. carpocapsae Isolate - 1, S. bicornutum and H. indica was studied with ten commonly used insecticides in the laboratory by direct exposure method. Chlorantraniliprole 18.5 SC at 0.005% was found to be the most compatible insecticide with S. carpocapsae isolate - 1 causing only 0.17 per cent mortality to IJs at 72 hours after treatment (HAT). Quinalphos 25 EC at 0.05% and chlorpyriphos20 EC at 0.05% were highly incompatible, causing 96.17 and 92.87 per cent mortality of the nematodes. Dimethoate 30 EC at 0.04% was the most compatible insecticide with S. bicornutum and caused only 0.60 per cent mortality at 72 HAT and was followed by azadirachtin 1 EC at 0.005% with 0.78 per cent mortality to the IJs. Quinalphos 25 EC at 0.05% caused 99.93 per cent mortality at 72 HAT. Heterorhabditis indica was compatible with all insecticides except quinalphos 25 EC at 0.05% which was moderately toxic resulting in 39.6 per cent mortality. The virulence, pathogenicity and multiplication of the survived IJs were not affected by the insecticide treatments. Parasitoids and EPNs were observed as potential candidates for the management of L. trifolii. Hence future studies on the bio-ecology and mass production of dominant parasitoids and standardization of methods to improve the efficacy of EPNs are suggested for the successful control of L. trifolii in polyhouses as well as in the field.
Open Access
Characterization, evaluation and formulation of beauveria bassiana (Bals.) strains against rice bug, leptocorisa spp. (Hemiptera:alydidae)
(Department of Agricultural Entomology, College of Agriculture, Vellanikkara, 2021) Nasiya Beegum, A N; KAU; Madhu Subramanian
The rice bug, Leptocorisaspp. is one of the most important sap sucking insect pests of rice in the tropics. Both nymphs and adults suck sap from developing rice grains during the milky grain stage, leading to discoloured, empty or half-filled grains. Yield loss due to the bug infestation ranges from 10 to 35 per cent. Management of the bug essentially involves spraying with insecticides, for want of safer options. Biological control of rice bug remains hampered by absence of ideal bioagents. The entomopathogenic fungus (EPF), Beauveria bassiana (Bals.) has been reported as infecting rice bug, from several parts of the world, including India. In this context, the present study was undertaken with the objectives of collection, isolation and molecular characterization of local strains of B. bassiana, evaluation against Leptocorisa spp., identification of a cost effective mass production technology for the selected strain of B. bassiana, and formulation of the most effective strain of B. bassiana. Surveys were conducted over two seasons during 2016-17 at major rice growing tracts of Alappuzha, Ernakulam, Thrissur and Palakkad districts of Kerala to collect EPF infecting rice bug. However, EPF infected rice bug cadavers were obtained only from one location i.e., Pattambi in Palghat district.As only one isolate was obtained, a potential fungal pathogen earlier obtained from rice bug at Vellanikkara, Thrissur and maintained at AICRP on BCCP was also included in further studies. The above two isolates were identified through study of colony characters as well as through ITS sequencingand Basic Local Alignment Search Tool (BLAST). The isolate from Vellanikkara was identified as Beauveria bassiana, while the isolate from Pattambi was identified as Choanephora cucurbitarum. The pathogenicity of the two isolates was assessed through laboratory as well as pot culture studies. In the laboratory, B. bassianaisolate recorded more than 90 per cent reduction in population of rice bug nymphs and adults five andseven days after treatment respectively at all concentrations evaluated while C. cucurbitarum recorded only 18 to 53 per cent reduction in bug population. Pot culture studies confirmed the superiority of B. bassianaisolate over C. cucurbitarum with B. bassiana treated pots registering over 99 per cent mortality by 20 th day after treatment as against 27 to 31 per cent mortality in case of the latter.B. bassianaisolate was further evaluated at its most effective concentration, under field conditions in both Thrissur and Palakkad districts.B. bassiana proved to be on par with the insecticide malathion from 10 th day onwards at both locations. The compatibility of B. bassiana isolate with selected insecticides and fungicides was assessed using poisoned food technique. The results showed that the insecticide acephate was the most compatible with 31.29 per cent growth inhibition while the fungicide propiconazole was the least compatible with 85.71 per cent inhibition. Methods for talc based, oil based and aqueous formulations of B. bassianawere standardized.Palm oil was identified as the most suited carrier for oil based formulation through inhibition zone technique as well as through assessment of viability of B. bassiana spores. Glycerol(3%), carboxy methyl cellulose (0.5%) and chitin (5%) formed the best adjuvants for oil based, aqueousand talc based formulations respectively, based on viable cfu count 30 days after storage. All the three formulations were as effective as malathion in reducing rice bug populations in field trials. However, talc formulation was significantly superior to the remaining formulations in terms of yield as well as grain damage. Talc, oil and aqueous formulations had shelf life durations of six, five and four months respectively.
Open Access
Effect of phorate applied for the control of bunchy top vector of banana Pentalonia nigroneroosa Coq. on the plant and in the soil environment
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 1989) Sitarama Rao, D; KAU; Mohandas, N
A series of experiments were carried out for ascertaining the basic problems related to the current recommendations for managing bunchytop disease of banana through the application of phorate. The absorption, translocation and metabolism of phorate applied in the soil was influenced more by the condition and age of the plant than by the dose of the insecticide. Since the application of 2.50 g ai/plant did not result in corresponding increase in the residue content or the bioefficacy in the early phases of crop growth, when compared to the 1.25 dose, the latter can be used without significant loss in efficacy. A definite dose-effect relationship existed between the phorate content of plant and the mortality of P.nigronervosa confined at feeding sites. The median lethal doses of the insecticide content of the plant tissue were higher during declining phase of absorption as compared to those obtained during the active absorption phase. The result indicated the lesser toxicity of some components in the total residue during the later phase of the crop. Application of phorate granules in leaf axils was less effective than the treatment done in the soil and hence the current recommendation to use less quantity of insecticide when applied in the leaf axils has to be altered. A simple technique for the separation, identification and quantification of phorate and its metabolites was developed. Phorate and phorate sulfoxide contents of the total residue showed inverse relationship with each other while the other metabolites did not exhibit a clear relationship among them. Phorate and phorate sulfoxide exhibited more positive direct influences on the morality of the vector than the other metabilites. The absorption and toxicity of the insecticide content in plants did not vary significantly up to 174 DAP, when applied @ 2.50 g ai/plant at different intervals after planting. Absorption was very low when the insecticide was applied at 180 and 210 DAP. For ensuring residues within tolerance limits (0.10ppm) in raw fruits, the insecticide treatment has to be limited to 150 DAP and for ripe fruits the limit can be extended up to 180 DAP. The absorption and persistence of phorate and metabolites was significantly higher in plants grown in summer season than in those grown in rainy season. The absorption of insecticide was high in sandy soils and it was lowest in black cotton soils during the active absorption phase. The insecticide persisted at effective levels for 75 days in sandy, 90 days in lateritic upland and 105 days in black cotton soil. Sulfoxidation of the thioether moiety was the dominent metabolic pathway in sandy soil while desulfuration pathway was predominent in the other three soils. Application of phorate at planting, @ 2.50 g ai/plant, did not adversely affect the soil microflora as observed at the time of harvest of the crop.
Open Access
Bionomics of pareuchaetes pseudoinsulata rego barros (lepidoptera:arctiidae) and its interaction with the siam weed chromolaena odorata king and robinson (asteraceae)
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1995) Lyla, K R; KAU; Abraham, C C
Studies were undertaken on the biology, morphometrics, feeding habits, factors affecting fecundity and fertility of Pareuchaetes pseudoinsulata King and Robinson (Arctiidae : Lepidoptera) and also the plant response of the weed host Chromolaena odorata L. at the College of Horticulture, Vellanikkara during 1990 – 1993. The morphometrics and morphology of the various immature stages and adults have been described. The total life-cycle of P. pseudoinsulata took a total of 46.75 days and the various developmental stages lasted for 5.5 days in eggs, 21.30 days for larvae (seven instars) 1.5 days for pre-pupa and 10.15 days for pupae at a mean ambient temperature of 28.40 C. In feeding trials to assess the relative preference of tender, mature, semi yellow and yellow leaves of C. odorata, it was found that the I instar larvae showed district preference to tender leaves as compared to mature leaves. The I and II instar larvae did not feed on semi-yellow and yellow leaves and they died of starvation when these types of leaves were offered for feeding. Consumption indices decreased as the age of larvae advanced and thus early instars consuming all the types of leaves recorded high indices. The rate of increase in larval weight gain was higher in later instars (VI and VII). Caterpillars feeding on mature, semi-yellow and yellow leaves showed higher Relative Growth Rate during IV to V stage, but during I to II stage, a high RGR was seen on larvae which fed tender leaves. Yellow. leaf diet for late instar larvae adversely affected their development and adult emergence. Highest fecundity was recorded when the parental sex-ratio of moths was kept at 1:1 level followed by 1:2 ratio and 2:1 in that order. Egg production and viability were significantly higher at 250 C and 75 per cent RH as compared to 300 C and 60 per cent RH. Adult food did not show any influence on fecundity but in respect of improvement of egg viability the treatments were advantageous. Total nitrogen content in leaves was maximum on the sixth day of release of four larvae per cage. Leaf nitrogen showed a declining trend when the larval load per plant was increased from the eighth day of release onwards. Soluble nitrogen content in leaves showed an increasing trend with increase in larval load per plant, but this however failed to reach significant levels. Chlorophyll content in leaves got reduced significantly at increased larval population loads and with passage of time of confinement. The natural enemies of P. pseudoinsulata consisted of avian fauna, spiders and ants and parasitoids. Predatory species of ants recorded in association with the insect included Lioponera sp. Oecophylla smaragdina Fabr. Solenopsis sp.and Monomorium sp. Occasionally NPV infection occurred in the laboratory as well as in field cultures causing substantial mortality. The implications of the various findings in reorienting the biocontrol strategies involving P. pseudoinsulata against C. odorata have been discussed.
Open Access
Studies on the extent of damages caused by pests of stored copra and controle of the important pests
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 1989) Nalina kumari, T; KAU; Mammen, K V
The magnitude and intensity of insect pest attack in stored copra, in the Southern Districts of Kerala, were assessed in an elaborate survey, adopting a random sampling technique for two years. The survey revealed that insects cause significant damage even in well preserved good quality copra stocked for more than five months. N. rufipes, O. surinamensis, A. advena and L. serricorne were the major pests recorded. The immature stages of N. rufipes, adults and immature stages of the other pests were seen inside the tunnels made between the endosperm and testa. N. rufipes and O. surinamensis were distributed widely, while the predominant insects observed at Nedumangad were A. advena and L. serricorne. All the insects were found breeding on copra from June to October. A positive correlation between moisture content of copra and the insect incidence was observed in the studies. The influence of A. flavus on the extent of damage caused by these pests showed that the presence of the mould was not a predisposing factor for insect attack. The extent of damage in copra due to the infestation by N. rufipes was 12.2 per cent at the end of sixth month whereas O. surinamensis caused only three per cent damage. When combind with fungus, the damage caused by N. rufipes was reduced by 50 per cent. This effect was not observed on O. surinamensis. The infection by the fungus adversely affected the oil content of copra and this effect was not altered by the preceeding or succeeding infestation of the insect. The insect attack alone caused significant reduction in oil yield of copra during the sixth month after exposure only. The quality of oil was adversely affected when infested by insects and fungus independently. The infestation of insects preceeding or succeeding fungal infection did not alter the adverse effect caused by them independently. The quantitative loss caused by the attack of N. rufipes and O. surinamensis to copra obtained from different varieties of coconut did not show significant variations. Among the different varieties tested LM and LO were more favourable to N. rufipes and DxT and TxD to O. surinamensis. Two to six fold increase in the longevity of the adults of N. rufipes was observed when they were provided with immature stages in addition to copra for feeding. N. rufipes and O. surinamensis caused significantly greater damage to copra under eight per cent and six per cent moisture levels respectively. The development of N. rufipes was totally arrested in copra with four per cent moisture content. The development of immature stages and adult population of N. rufipes were higher in copra containing eight per cent moisture level and those of O. surinamensis in copra containing six per cent moisture. The response to moisture fluctuations was more conspicuously seen in O. surinamensis than in N. rufipes. Though the population of insects were found to be high in reused gunny bag followed by heap storage, the extent of damage was higher in heap storage than in reused gunny bags. High populations of N. rufipes and O. surinamensis were recorded from heap and reused gunny bags respectively. Low populations of insects were recorded in copra stocked in polythene/alkathene lined gunny bags and netted polythene bags. But the oil extracted from copra stored in these types of bags gave significantly higher acid values. In the trials done to find out a safe prophylactic method of control against pests of copra, malathion and phoxim proved more toxic to N. rufipes and malathion and fenitrothion to O. surinamensis. When these insecticides were evaluated for their persistence on gunny bags, malathion 0.4 per cent gave protection up to five months and fenitrothion 0.8 per cent up to six months. The residues of malathion and fenitrothion came below tolerance limits, 15 and 60 days after treatment respectively . For complete control of the major pests of copra 4.5 g/m (2.5 g ai/m ) of aluminium phosphate with one day exposure period was found adequate. The residue of phosphine in the copra fumigated as above was below tolerance limit.
Open Access
Resurgens of brown planthopper Nilaparvata Lugens (stal) on rice treated with various insectisides
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 1989) Thomas biju, Mathew; KAU; Mohan das, N
A series of green house experiments were carried out for screening the insecticides, fungicides and herbicides recommended for the control of pests, diseases and weeds infesting rice in Kerala, for their resurgence inducement in N. lugens. Among the thirteen insecticides screened, each at three doses and applied at three critical growth stages of the crop as well as at their possible combinations, methyl parathion, deltamethrin, fenitrothion, fenthion, quinalphos and carbaryl were identified as resurgence inducing insecticides with no apparent differences among themselves in the intensity of resurgence caused, HCH, dimethoate, monocrotophos, phosphamidon, phorate, BPMC and carbofuran were found to be free from resurgence inducement and some of them even exerted a significant suppressing effect on the progeny production of N. lugens. There was no carry over of resurgence effect over generations. The results of the experiments also revealed that: 1. The manifestation of resurgence inducing property of insecticides was more at the higher doses than at the field doses or lower doses. 2. The frequency of occurrence of resurgence among the different treatments with resurgence inducing insecticides showed that a single application at any of the three critical growth stages of rice and two applications combining any two of the three growth stages were on par while three consecutive treatments covering all the three growth stages was more favourable for manifestation of resurgence. 3. The growth stages of the host plant had significant influence on the manifestation of resurgence inducement of insecticides. It varied with the properties of insecticides used. Some manifested resurgence at tillering, some at panicle initiation and none at booting stage. 4. The resurgence effect induced by the insecticides was found to last in the treated plants for a period of 15 to 20 days after treatment and the results indicated, that there was no cumulative effect by repeated treatments on insect populations. In the light of the above findings the method of screening resurgence inducing insecticides in the green house was standardized as the application of the insecticide at doses higher than the field doses thrice covering the tillering, panicle initiation and booting stages preceeding the exposure of insects for assessment of progeny production which may be done at 15 days after the third application. In further screening adopting the procedure standardized above malathion, methyl demeton, FMC 35001, fenvalerate, permethrin and cypermethrin were found inducing resurgence in N. lugens. The granular insecticides were screened giving two treatments (tillering + panicle initiation) and exposing insects at 30 DAT for egg laying. Results revealed that diazinon, phorate, cartap and carbofuran caused resurgence of N. lugens. Endosulfan, formothion, phosalone, methamidophos, chlorophyriphos, DDVP and their combinations with HCH or carbaryl (liquid formulations), aldicarb, quinalphos and sevidol (granular) were free of resurgence hazard. At the recommended doses and methods of application of fungicides zineb, mancozb, captafol, ediphenphos, kitazin, carbendazim and carboxin and the herbicides 2, 4-D (sodium salt and ester), pendimethalin, fluchloralin, butachlor, propanil and thiobencarb did not post any resurgence problem. The inducement of resurgence by insecticide was seen significantly influenced by the variety of host plants of the insects involved. The levels of plant mediated resurgence inducement and resistance of the plants to insect attack were not mutually related. In screening insecticides for the control of a pest in an agroecosystem, the interaction of the popular varieties of the crop available in the area with resurgence inducement also should be studied. The resurgence inducing mechanism of six identified insecticides was studied in detail. The results of a series of green house and laboratory experiments revealed that : 1. Resurgence inducing insecticides brought about some morphological changes in the crop causing some improvements in the stand but the magnitude of the changes were not adequate to influence the attraction of the insects or build up of the pest population. 2. The application of the insecticides caused significant variations in the nutrient content and biochemical constituents of treated plants causing consistent changes in the total nitrogen, free sugars and free amino acid contents. 3. The feeding of N. lugens on treated plants was significantly higher as indicated by the feeding indices. 4. The correlation studies and path coefficient analysis of the data relating to the magnitude of changes in the above factors caused by the application of insecticides could be attributed as the major cause of plant-mediated resurgence inducement. The direct application of resurgence inducing insecticides revealed that some of the insecticides which showed plant mediated resurgence (methyl parathion, deltamethrin and carbaryl) had direct stimulating effect also on the progeny production of N. lugens at sublethal doses while some (fenthion and fenitrothion) did not show any increase in progeny production and some (quinalphos) showed only marginal effect. While carbaryl and methyl parathion were more stimulatory at lower levels, deltamethrin stimulated reproduction at both the lower and higher levels. The field experiment revealed that the resurgence observed in the field was the added effect of plant-mediated resurgence observed in green house experiments and the direct effect of the pesticides caused by their sublethal doses. In general the conclusions from the green house experiments were in agreement with the results obtained from the field. It was seen that the changes in predatory population in field caused by the application of pesticides did not contribute significantly to the inducement of resurgence in N. lugens. It was also observed that the assessment of plant induced resurgence of insecticides in green house experiments and the direct effects of the toxicants on the insects will serve as an effective alternative elaborate field experiments for evaluating the resurgence effect of insecticides.

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