Loading...
Resurgens of brown planthopper Nilaparvata Lugens (stal) on rice treated with various insectisides
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 dose...
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Ph.D Thesis |
| Language: | Undetermined |
| Published: |
Vellayani
Department of Agricultural Entomology, College of Agriculture
1989
|
| LEADER | 06889nam a2200181Ia 4500 | ||
|---|---|---|---|
| 003 | OSt | ||
| 005 | 20160217142217.0 | ||
| 008 | 140128s9999 xx 000 0 und d | ||
| 082 | |a 632.6 |b THO/RE | ||
| 100 | |a Thomas biju Mathew | ||
| 245 | |a Resurgens of brown planthopper Nilaparvata Lugens (stal) on rice treated with various insectisides | ||
| 260 | |a Vellayani |b Department of Agricultural Entomology, College of Agriculture |c 1989 | ||
| 502 | |b PhD | ||
| 520 | 3 | |a 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. | |
| 700 | |a Mohan das N (Guide) | ||
| 942 | |2 ddc |c TH | ||
| 999 | |c 25125 |d 25125 | ||
| 952 | |0 0 |1 0 |2 ddc |4 0 |6 632_600000000000000_THORE |7 0 |9 33129 |a KAUCLV |b KAUCLV |c THESES |d 2014-03-18 |o 632.6 THO/RE |p 170169 |r 2014-03-18 |w 2014-03-18 |y TH | ||