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Theses

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1982 - 19848
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Subject: Agricultural Entomology × Author: KAU × End date: 1984 × Start date: 1982 ×
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    ThesisItemOpen Access
    Pest complex associated with mango inflorescence and their control
    (Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1984) Satheesan, N V; KAU; Abraham, C C
    In a survey conducted during 1982-83 in the State of Kerala to study the incidence of various insect pests associated with mango inflorescence with reference to their seasonal history, a total of ten insect pests were recorded. The hoppers idioscopus niveosparaus Leth. and I. clypealis Leth. were found to be widely distributed in the State. Significant variability was not detected among the population loads of I. niveosparsus in different districts, while in the case of I. clypealis such variations were significant. The heaviest populations of the latter was recorded from the Calicut District. The seasonal changes in I. clypealis populations were recorded only in the two Districts of Calicut and Trivandrum. I. niveosparsus showed a well defined peaks in the Palghat and Wynad districts. The fluctuations I. niveosparsus and I. clypealis populations have been discussed with reference environmental conditions. Procystiphora mangiferae Felt. is reported for the first time from the State from the Wynad and Cannanore Districts. Infestations by the pest led to transformation of the floral buds to conical galls. In the Wynad District, there was a well defind population peak in March, while in the Cannanore District a district crest waslacking. The mango blister midge, Erosomyia indica grover and Prasad was recorded to occur in association with P. mangiferae in these two districts. The larvae of E. indica tunnel into inflorescence axis and cause ovate galls thereby causing losses. Bombotelia jocosatrix Gn. was recorded from the Cannanore, Palghat, Trichur and Alleppey Districts throughout the flowering season. Eublemma anguilifera Moore as well as another unidentified spp. of Eublemma were recorded to occur throughout the State, except in the wynad District. The seasonal fluctuations of this pest were significant only in the Palghat District. An unidentified species of Cacoecia was recorded for the first time as a minor pest of mango inflorescence. The larvae fed on flowers and floral buds. The other pests observed during the course of the survey were Rapala manea Hewitson, Haplothrips ganglbaueri Schmutz, Dichocrosis punctiferalis Guenee and an unidentified Geometrid. The bio-efficiency of monocrotophos applied by two methods, namely, stem injection and stem banding, against the Idiocerine hoppers infesting mango inflorescence was evaluated in a separate experiment. The relative toxicity of the insecticide was determined from the time- mortality relationship between the insecticide reaching the inflorescence of treated trees and the mortality of the fourth instar nymphs of I. niveosparsus. The LT -50 values of the nymphs following application of the insecticides by the stem injection method was found to be substantially lower than the corresponding values for the stem banding method of application. It was thus evident that the toxicant moved at a faster pace when administered by the stem injection method. The variations in the pattern of translocation of the toxicant under the two methods of administration have been discussed. The residues of monocrotophos on freshly formed mango fruit at five weeks after application by the stem injection method at 4 ml and 2 ml ai/tree were 0.3600 ppm and o.3750 ppm respectively. The corresponding residues in the mango fruit consequent on stem banding method of administration were 0.0550 ppm. The implications of the above results in formulating control methods against Idiocerine hoppers infesting mango inflorescence have been discussed.
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    ThesisItemOpen Access
    Taxonomic studies of leaf and plant hoppers associated with paddy in Kerala
    (Department of Entomology, College of Horticulture, Vellanikkara, 1984) Abdulla, K; KAU; Mammen, K V
    Taxonomic study on the leaf and plant hoppers of paddy was conducted to find out the various specious of leaf and plant hoppers associated with paddy in Kerala. Paddy fields from two important paddy growing tracts of Kerala viz., Trichur and Palghat were selected and weekly collections of hoppers were made. Collections were made with a fine mesh hand net for the entire cropping season from transplanting upto harvest. Fixed numbers of sweeps were taken from the same field in order to get an idea about the population fluctuations. Collections from each field for each week were separately preserved in homeopathic vials with collection data. Later insects in all vials were sorted out, number of specimens collected in each week were noted, sexes separated, and each species were preserved in separate vials. Vials were serially numbered and collection data were noted under each serially numbered species. Genitalia of males as well as general form and colouration of all species were stidied. However genitalic studies of Exitianus indicus (Dist.) and Nisia nervosa (Motsch.) could not be conducted for want of male specimens. Altogether nine species were collected viz., Nephotettix Virescens (Dist.), N. nigropictus (Stal), Recilia dorsalis (Motsch.) and Exitianus indicus (Dist.) coming under Cicadellidae, Nilaparvata lugens (Stal), Sogatella furcifera (Horv.),Matutinus pusanus (Dist.) belonging to Delphacidas and Nisia nervosa (Leth) under Meenoplidas. Among these species all but M. pusanus were reported to be occurring on paddy in India and other East Asian countries, while E. indicus and N. nervosa were not observed by earlier workers from Kerala. Apart from these, two male and two female specimens of Nephotettix showing variations in characters from N. nigropictus and N. virescens were also obtained. These may be natural hybrids between N. virescens and N. nigropictus. Certain morphometric studies were conducted using head measurements viz., eye diameter to interocular distance and /or vertical distance next to eye to median length of Vertex. It was found that there is difference between male specimens of N. virescens and N. nigropictus with regards to the ratio of vertical distance next to eye to median length of vertex; and in females of these species there is difference between the ratios of eye diameter to interocular distance. Similarly there is difference between male specimens of N. lugens and S. furcifera with regards to the ratio of eye diametor to interocular distance. Studies on the seasonal abundance of leaf and plant hoppers revealed that there is variation in the predominant species present in each area.
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    ThesisItemOpen Access
    Studies on the pests of chromolaena in Kerala
    (Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1983) Lyla, K R; KAU; Joy, P J
    A detailed survey was conducted in Trichur District and an objective survey in five other selected districts of the Kerala State during November 1980 to October 1981 to study the pests of choromolaena odorata Linn. Observations on the nature of damage and population density have been made during the survey. Details of the insects recorded on the weed are given below. 1. Hemipteran pests 1.1 Aphis spiraecola patch These aphids were recorded in all the areas surveyed and alate and apterous forms were available. There are four instars each occupying one to two days and the adult six to ten days. The alate forms occurred at relatively lower levels compared to apterous form. In both cases, maximum population was in July irrespective of the topographic conditions. Both the nymphs and adults such sap from the tender shoots thereby reducing the vigour of the plant. 1.2 Aphis fabae scopoli Both apterous and alate forms were observed. Here also the aphid population attained peak level in July both in medium hilly areas and plains. The aphid infested leaves presented a crinkled appearance. 1.3 Braschycaudus helichrysi kitb These were noted in higher elevations like Idukki and Wynad areas and were absent in Trichur District. The aphid attacked leaves become folded and rolled longitudinally. 1.4 Coptosoma sp. These bugs were observed throughout the growth phase of the weed. Adults suck sap from tender parts of the plant without causing any serious damage. 1.5 Sepontia nigrofusea Dist. These bugs suck sap from the weed causing negligible damage and were present in very few number at Pananchery Village. 1.6 Tettigella ceylonica melich. These appeared only as casual feeders of C.odorata and their populations were extremely low for affecting any appreciable damage. 1.7 Bemisia tabaci. Gen. The adult suck sap from tender parts of the weed and the population level was very low. 1.8 Leptocorisa acuta thumb. These were found in the Puzhakkal Village and the bugs suck sap from the weed. 1.9 Riptortus pedestris Fb. The adults suck sap from tender shoots and were found in few number. 1.10 Dysdercus koenigii Fb. The adults suck sap from the weed without causing any appreciable damage. 1.11 Leptocentrus sp. These bugs suck sap from the plant throughout the growth phase of the weed, but the population count was very low. 1.12. Cocosterphus minutes Fabricius These insects were present in few numbers and suck sap from the weed. 2. Coleopteran pests 2.1 Apion sp. As a result of feeding of the weevil irregular holes are formed on leaf surface. These feed on the flowers during the flowering season. 2.2 Unidentified curculionid They eat away portions of the leaf creating holes on the surface. 2.3 Astycus aurovittatus Heller The weevil was found feeding the foliage of the weed during December. 2.4 Amblyrrhinus sp. They feed on the leaves and flowers by cutting small holes on them. 2.5 Mylabris sp. These feed on the weed flowers occasionally. 2.6 Corynodes sp. These beetles feed on the leaves making irregular holes here and there. 2.7 Carvedon sp. These insects were found feeding on the flowers occasionally. 3. Lepidopteran pests 3.1Pericallis ricini Fb. The young larvae feed on the surface tissue of young leaves and in the later instars they feed both by scrapping and by eating the whole leaf lamina. 3.2 Discrisia oblicua wlk. Larvae found defoliating the weed 4. Dipteran pest 4.1 Unidentified agromyzid The larvae mine into the leaves and eat through the mesophyll leaving the two epidermal layers intact. 5. Thysanopteran pest 5.1 Haplothrips gowdeyi franklin Both nymphs and adults feed by lacerating the tissues of the inflorescence and found in numbers. Out of 23 species of insects recorded to occur on c. odorate coptosoma sp.(plataspididae:Hemiptera),Sepontia nigrofusca (Plataspididae: Hemiptera),Tettigella ceylonica (Cicadelliade: Hemiptera)Leptocorisaacuta (Coreidae: Hemiptera)Riptortus pedestris(Coreidae: Hemiptera)Coccosterphus minuts(Membracidae: Hemiptera)Astycus aurovittatus (Curculionidae:Coleoptera) Amblyrinus sp.(Curculionides sp. Coleoptera)Mylabris sp.(Meloidae:Coleoptera)Corynodes sp.(chrysomelidae: Coleoptera) Caryedon sp.(Bruchidae: Coleoptera),pericallia ricini (Arctide:Lepidoptera) and Haplothrips gowdeyi(phloethripidae:Thysanoptera) are reported for the first time. Among the insects, the most widespread and numerous were A.spiraecola and A.fabae in that order.
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    ThesisItemOpen Access
    Joint action of nuclear polyhedrosis virus of Spodoptera (Fabricius) with insecticides and its applicability in pest control
    (Department of Agricultural Entomology, College of Agriculture, Vellayani, 1984) John, V Cherian; KAU; Vasudevan Nair, K P
    Experiments were conducted to study the joint action of nuclearpolyhedrosis virus (NPV) of Spodoptera litura (Fabricius) and five insecticides viz., quinalphos, carbaryl, BHC, monocrotophos and permethrin. The investigation carried out included bioassay of the virus and insecticideson third instar larvae of S.litura, effect of different combinations of the virus and insecticides on larval mortality and the effect of simultaneous and sequential application of virus and insecticides for the control of pest.
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    ThesisItemOpen Access
    Biology, Bionomics and control of coconut cockchafer Leucopholis coneophora Burm.
    (Division of Agricultural Entomology, College of Agriculture, Vellayani, 1983) Abraham, V A; KAU; Mohan Das, M
    The biology of the coconut cockchafer Leucopholic coneophora Burm. was studied in detail for the first time. Techniques for rearing the pests from egg to adult in potted palnts kept in field were standardized. The egg laying behaviour of adults was observed. The morphological changes off eggs, different instars of grubs and pupae during development were studied in detail. The changes in immature stages of male and female insects were traced separately. The general morphology of different instars of the grubs was studied in full with a view to finding distinct identifying characters for each.
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    ThesisItemOpen Access
    Pathogenicity of burrowing nematode, Radopholus similis (Cobb 1893) Thorne 1949 on banana
    (Department of Entomology,College of Agriculture, Vellayani, 1982) Satyanarayana, P; KAU; John Kuriyan, K
    Pathogenicity of the burrowing nematode,Radopholus similis on banana was studied at the College of Agriculture, Vellayani with three levels of population viz. 1000', 10,000 and 1,00,000 nematodes at five different growth stages of the crop starting from 45 days after planting and with 45 days interval. I t was observed that the general growth of the plant was retarded. The reduction was directly proportional to the initial inoculum used and the period of infestation. A reduction of 36*84 per cent was seen in the yield of plants inoculated earlier with 1,00,000 nematodes and as high as 60.52 per cent reduction in weight of the roots in the plants treated with 10,000 nematodes. Nematode population was found to reach its peak during the flowering season of the plant and decreasing thereafter. The multiplication of the nematode was observed to be inversely proportional to the Initial inoculum level. Population of even 1000 nematodes at active growth stage was enough to cause severe reduction in the plants growth. It was seen that plants could withstand the damage caused by the nematode feeding at later stages Le. after 180 days after planting. So the plants should be protected from the nematodes at earlier stages. The histological changes in the roots infested by nematodes revealed that the nematodes feed on the cortical tissue causing reddish brown lesions on the roots and nematodes could not enter the stelar region of the root even under severely infested conditions
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    ThesisItemOpen Access
    Effect of synthetic pyrethroids on the pests of paddy
    (Department of Agricultural Entomology, College of Agriculture, Vellayani, 1982) Balaji, T S B; KAU; Mohan Das, N
    The relative efficacy of four synthetic pyrethroide against the important rice pests was assessed through a field experiment laid out at the Model Agronomic Research Station karamana, during 1981, taking carbaryl as standard. Against the rice gall midge Pachydiplosis oryzae cypermethrin (50 and 25 g ai/ha) and permethrin (50 g ai/ha) were found superior, The low variation in tho percentage incidence of silver shoots in plots treated with pyrothroids and carbaryl showed that the use of the former category of pesticides is not justified due to the high, cost involved.
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    ThesisItemOpen Access
    Protection of stored cowpea seeds (Vigna unguiculata (L) (Walp) from infestation by the pulse beetle Callosobruchus maculatus F. (Bruchidae : Coleoptera)
    (Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1982) Purnamma, B; KAU; Mammen, K V
    Studies were conducted to assess the effect of different materials in protecting cowpea seeds against attack of pulse beetle, Callosobruchus maculatus in storage for a period of six months. Rhizome bits of sweet flag, neem kernal powder, activated charcoal powder, carbaryl 5% dust, etrimphos 2% dust were directly mixed with seeds