Thumbnail Image

Theses

Browse

1987 - 19895
Reset filters
Subject: Entomology × End date: 1989 × Start date: 1987 × Thesis Type: M.Sc ×
Reset filters

Search Results

Now showing 1 - 5 of 5
  • Thumbnail Image
    ThesisItemOpen Access
    Integrated control of fruit fly Dacus cucurbitae Coq: Trypetidae: Diptera on bitter gourd
    (Department of Entomology, College of Agriculture, Vellayani, 1989) Jalaja, P N; KAU; Remamony, K S
    Bittergourd is very popular among the vegetable growers in Kerala. Fruit flies take a heavy toll of this crop and intense use of pesticides is a common practice of cultivators often leading to serious residue hazards in the marketed fruits. In the present investigation an attempt was made to standardise non-insecticidal methods of control for tackling this pest problem. Laboratory evaluation of potential attractants of fruit flies viz. eugenol, eucalyptus oil, citronella oil, borar, ammonium phosphate, vanilla essence, jaggery, sugar, vinegar, honey, toddy and bittergourd fruits were screened for baiting the adults of D. cucurbitae. Eugenol, eucalyptus oil, citronella oil, borax, ammonium phosphate and vanilla essence did not show any attractiveness to the flies. Three graded concentrationsof honey, sugar, jaggery, toddy and vinegar were tested for their attractiveness to the files in the laboratory. The result showed that (1) honey at the highest concentration of 1% attracted the maximum number of flies (2) toddy was not effective for attracting D. cucurbitae. (3) immature stages of bittergourd fruits showed poor aatraction and (4) ripe bittergourd fruits showed poor attraction and (4) ripe bittergourd fruits showed maximum attraction to the files up to 12 h of exposure.
  • Thumbnail Image
    ThesisItemOpen Access
    Studies on insect pests and diseases of rice earhead and their control
    (Department of Entomology, College of Agriculture, Vellayani, 1987) Annie Thomas; KAU; Rajan Asari, P A
    A random sample survey on insect pests and diseases infesting rice during, flowering stage was conducted to collect information on the occurence of pests and diseases on rice earhead of different localities in Trivandrum district. Itcould be observed that L.acuta was the most important pest occurring throughout the area surveyed . The importance of rice bug was further proved by the mean number of insect present in different localities. The mean number of rice bug varied from 0.25 to 2.45 which showed the existence of considerable variation according to localities and varieties. The high yielding varieties invariably were seen more susceptible to the pest infestation than the local cultivars.
  • Thumbnail Image
    ThesisItemOpen Access
    Studies on the nature and extent of damage caused by insect pests to stored tapioca chips
    (Department of Agricultural Entomology, College of Agriculture, Vellayani, 1988) Ramla Beevi, S; KAU; Mammen, K V
    A survey on tho population of different stages of insect pests and the extent of damage caused by these insect to stored tapioca chips were conducted at monthly intervals for a period of four months from August 1984 to November 1934 in ten centres of Trivandrum District via. Palode, Parasala, Nedumangad, Venjaramood, Pothencode, Chirayinkil, Vembayon, Chalai, Sreekaryam and Mangalapuran, where tapioca chips wore stored. Among the various posts recorded three species viz. tapioca weevil
  • Thumbnail Image
    ThesisItemOpen Access
    Crop loss caused by root-knot nematode (Meloidogyne incognita Kofoid) infesting Coleus parviflorus and its control
    (Department of Entomology, College of Agriculture, Vellayani, 1988) Sosamma, P; KAU; Ravindran, Nair K K
    Crop loss caused by the root-knot nematode Infesting Coleus parvlflorus and its control was studied in a pot culture experiment and a field experiment in the Department of Entomology, College of Agriculture, Vellayani, Trivandrum, during August to December, 1986. The number of leaves, shoot length, fresh shoot weight and weight of tubers obtained were less in inoculated plants than in control. The yield and growth parameters showed a negative correlation with the population of nematodes. A high positive correlation was noticed between tho tuber weight and the number of leaves and shoot weight of coleus. The shoot length did not influence the tuber yield significantly
  • Thumbnail Image
    ThesisItemOpen Access
    Major pests of ginger in Kerala and their control
    (Department of Entomology, College of Agriculture, Vellayani, 1989) Rajan, Mathew; KAU; George, Kosy
    A survey conducted in Kottayam and Idukki Districts (ginger tracts) of Kerala, adopting multistage random sampling technique, revealed that D. punctiferalis is the major pest infesting the crop in both the Districts. The first instar larvae bored in at the fourth or fifth leaf axil of the psuedostem and caused the drying up of the distal part. Then the larvae emerged out and tunneled in at the base of the psuedostem. The lower part of the stem did not dry up. The pest had a uniform distribution in the two Districts. The extent of shoot damage ranged between 23.59 and 24.92 per cent. The incidence of the pest was not significantly associated with the soil type in which the crop was grown or with the age of the crop. The damage observed was higher during August, September and October and started declining from November. The possible yield loss for the mean damage of 23 to 24 per cent of the psuedostem could be estimated as 25 per cent based on the observations of CPCRI (1981 a). A field experiment conducted in the two Districts showed that the avoidable yield loss caused by D. punctiferalis was around 40 per cent. Application of granules (carbofuran and phorate) caused initial reduction in the damage done by D. punctiferalis but it did not persist to reduce the final yield loss caused by the pest. Need based spraying of dimethoate or quinalphos 0.05 per cent emulsion controlled the pest effectively. Spraying of quinalphos was more economical. Studies on the nature of damage done by the rhizome maggot M. coeruleifrons revealed that the entry of the maggot in to the rhizome occurred only when there were mechanical injury at the collar region or the tissues at the point was softened by prior infection of bacteria or fungi. A pot culture study showed that the fly maggots invaded the rhizome infected by fungus and not vice versa. The fly was seen distributed in both the Districts, but the distribution was discontinuous. The incidence in the high ranges was very low. The incidence of the pest was positively correlated with the rhizome rot disease incidence. The biology of the pest was studied in detail and the life stages of the pest have been described in detail. The leaf roller U. folus was observed as a minor pest of ginger and it was distributed in a few locations covered in the survey. The leaf spot disease was prevalent in Idukki and Kottayam Districts the mean indices of the disease being 1.627 and 1.043 respectively. The disease commenced in July, reached the peak in September and continued up to November. Soft rot disease was prevalent in Idukki and Kottayam Districts; but the distribution was discontinuous. It was less in higher elevations of Idukki District. The peak incidence of the disease was in September. It was less common in forest lands. the relative humidity was positively correlated with disease incidence while the age of the crop had a negative influence. Meloidogyne sp and Radopholus sp were obtained from the root and soil samples collected from the different locations covered in the survey. But population was too low to cause significant crop loss. Low population of Helicotylenchus sp. in root and soil samples and Criconema sp, Xiphinema sp and Mononchus sp in soil samples were also recorded.