Browsing by Author "Lyla, K R"

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Biology and management of orchid pests
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1998) Sajitha Kumari; Lyla, K R
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, 1993) Lyla, K R; 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.
Comparative performance of blackgram varieties in Chalakudy command area
(Kerala Agricultural University, 1984) Reena Grittle Pinhero; Baby Latha, A K; Lyla, K R; Thomas, A I
Comparative performance of cowpea varieties in rice fallows
(Kerala Agricultural University, 1984) Babylatha, A K; Reena Grittle Pinhero; Lyla, K R; Thomas, A I
The performance of eight varieties of cowpea under irrigated conditions in the Malampuzha Command area was studied in the summer season of three consecutive years. Ptb 1, HG 22, Pusa 2 and C 152 were found to be superior varieties for cultivation under irrigated conditions during summer season in rice fallows.
Establishment of cyrtobagous salviniae sands (Curculionidae:Coleopjera) on salvinia molesta mitcheil in Kerala
(Kerala Agricultural University, 1984) Joy, P J; Satheesan, N V; Lyla, K R; Joseph, D
Establishment of Pareuchaetes Pseudoinsulata Rego barros (Ammalo insulata walk.), an arctiid caterpillar, for the biological control of chromolaena odorata
(Kerala Agricultural University, 1987) Satheesan, N V; Lyla, K R; Joy, P J; Joseph, D
Hairy caterpillar euchromia polymena Linn.- A serious pest of Tylophora Indica (Burm.F.) Merr. and Ipomoea Mauritiana Jacq.
(Kerala Agricultural University, 1992) Lyla, K R; Reghunath, B R; Joy, P J
Hirsutella Thompson II var. Synnematosa Samson, Mccoy & O'donnell on coconut mite aceria (Eriophyes) guerreronis (Keifer) - a new report from India
(Kerala Agricultural University, 1999) Pathummal Beevi, S; Beena, S; Sukumara Varma, A; Lyla, K R; Maicykutty P Mathew; Nadarajan, L
Insect pests of Chromolaena odorata (Eupatorium odoratum)
(Kerala Agricultural University, 1987) Lyla, K R; Joy, P J; Abraham, C C
Lily caterpillar polytela gloriosae fab.(Noctuidae : Lepidoptera), a serious pest of gloriosa superba L.
(Kerala Agricultural University, 1992) Lyla, K R; Reghunath, B R; Viswanathan, T V
Management of Limax sp. (Limacidae: Stylommatophora) - a pest of orchids in Kerala
(Kerala Agricultural University, Vellanikara, 2001) Sajitha, Kumari; Lyla, K R
Metabolic changes in siamweed, Chromolaena odorata induced by feeding of weed killer, Pareuchaetes pseudoinsulata (Arctiidae: Lepidoptera)
(Kerala Agricultural University, Vellanikara, 2001) Lyla, K R; Abraham, C C; Joy, P J
The arctiid caterpillar, Pareuchaetes pseudoinsulata Rego Barros, has been identified as a potential bio-control agent of the Siam weed, Chromolaena odorata King and Robinson. The present studies were to assess the metabolic changes in the plants induced by larval feeding. The total nitrogen content in leaf samples showed significant variations on 4th, 6th, 8th, 10th, 12th, and 15th days after releasing variable number of Pareuchaetes larvae. Total nitrogen was maximum in the leaves, on the sixth day of release of four larvae per plant. Leaf nitrogen showed a declining trend when the larval load per plant was increased from the eighth day of release onwards. The nitrogen content was the least on 15th day after release of twelve larvae. Nitrate nitrogen content showed an increasing trend with increasing number of larvae and days after release. Chlorophyll content in the leaves got reduced significantly with increased larval population load in plants and with the passage of time of confinement of larvae.
New record of Leptoglossus Australis (Fabr) as a pest of Bittergourd in Kerala
(Kerala Agricultural University, 1986) Lyla, K R; Joy, P J; Peter, K V
Population fluctuations of aphid pests of Chromolaena Odorata (Eupatorium Odoratum) in Kerala
(Kerala Agricultural University, 1985) Lyla, K R; Joy, P J; Abraham, C C
In studies on the population fluctuations of the aphidpesfsof Chromolaena odorata Linn, in the plains and medium hilly localities of Trichur district (Kerala State), it was found that Aphis spiraecola Patch and Aphis fabae Scopoli occurred at peak levels in July in both situations, the diversity of occurrence per unit area being also higher in July. Brachycaudus helichrysi KItb. occurred at higher elevations of the Idukki, Wynad districts causing complete damage to the plants. Nymphs and adults of A. spiraecola and A. fabae fed on tender leaves and shoots causing severe leaf crinkling. Consequent on feeding by B. helichrysi the leaves became rolled and the entire plants showed wilting symptoms. As candidates for the bio-control of C. odorata in Kerala, these aphids do not appear to be quite promising.
Studies on the pests of chromolaena in Kerala
(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1983) Lyla, K R; 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.
Survey of the pests of orchids
(Kerala Agricultural University, Vellanikara, 2001) Sajitha, Kumari; Lyla, K R
A survey was conducted on the pests of orchids in Trichur, Ernakulam, Alappuzha and Kottayam districts of Kerala. The grass hopper Oxya chinensis, spiralling white fly Aleurodicus dispersus, flower thrip Megalurothrips distalis, Bihar hairy caterpillar Diacrisia obliqua, tobacco caterpillar Spodoptera litura, red ant Monomorium indicum, beetle pest Lema sp. and banded blister beetle Mylabris pustulata were the different insect pests collected and studied. Non-insect pests studied were sow bug Oniscus aseltus, land snail Arioplianta sp., black slug Anon sp. and grey slug Umax sp.