摘要:

Every year, between March and August, the Onchocerciasis Control Programme (OCP) is invaded by large numbers of the onchocerciasis vector,Simulium damnosums.l., from breeding sites outside and to the south‐west of the programme area. One suspected source of this annual reinvasion lies in the mountainous area of South‐eastern Guinea along the headwaters of the Sassandra River. After a feasibility study, these watercourses were treated by helicopter with the organophosphate larvicide, temephos, from March to August 1985. It was shown that aerial treatments in this region of high mountains and forests were feasible and the operation produced over 90% reductions in biting and transmission in the reinvasion zones of Northern Ivory Coast and South‐western Burkina Faso. It was concluded that the Upper Sassandra tributaries in Southeastern Guinea were the principal source of vectors invading this region of the OCP and that these breeding sites must be treated annually to maintain biting and transmission in Ivory Coast and Burkina Faso at a tolerable level.

ISSN:0143-6147    

DOI:10.1080/09670878509370997

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Toxicities o1 12 chemical insecticides to wild‐caught tsetse flies,Glossina palpalis palpalisin Nigeria were measured by topical application. Median lethal doses (as ng per fly) at 48 h after application for older flies, males (females), were: DDT 331 (700), dieldrin 14 (46), endosulfan 8 (15), malathion 193 (273), fenitrothion 47, pirimiphos methyl 31 (45), tetrachlorvinphos 14 (33), sumicidin 28 (58), neopynamin 12 (15), sumithrin 10 (8), permethrin 4.4 (5.9), deltamethrin 0.45 (0.94). Lethality expressed as dose per whole fly can be termed effective toxicity/tolerance and those expressed as dose per weight unit of fly can be termed intrinsic (or true) toxicity/tolerance. Generally, effective tolerance was greater for females than males, especially for older flies. However, intrinsic tolerance was often about equal for the sexes or greater for males. Regardless of sex, effective tolerance increased with increasing fly age and intrinsic tolerance increased during later ageing but not during early ageing. This suggested that protecting mechanisms developed during ageing. Flies fed a few hours before treatment in 1979–1982 were more tolerant of three organochlorines and three organophosphates than flies fed the day before treatment in 1974–1975, probably due to diversion of poisons from sites of action into inert undigested blood. However, results and statistical analysis suggested a slight increase in true tolerance of males to DDT during the intervening years. Continued monitoring of tolerance in the fly populations is recommended.

ISSN:0143-6147    

DOI:10.1080/09670878509370998

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Studies of population fluctuations of the oriental fruit fly,Dacus dorsalisHendel, were conducted in two guava orchards from January 1980 to December 1981 using methyl eugenol traps. Three distinct population peaks were recorded in March/April, May/June and September/October during both years. These peaks coincided with the ripening of guava and mango fruits which are the major hosts ofD. dorsalis.Abiotic factors also played an important role in regulating the fly population. Trap catches were significantly and positively correlated with maximum and minimum temperatures, day degrees (or thermal units) and maximum relative humidity. Trap catches were significantly and negatively correlated with minimum relative humidity. The placement of fruit fly traps in different directions and positions in orchards had no apparent effect on the catches of flies. However, traps placed in the edges of the orchards caught significantly higher numbers of flies than traps placed in the centre.

ISSN:0143-6147    

DOI:10.1080/09670878509370999

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Biology, ecology and damage potential of the sorghum midge,Contarinia sorghicolaCoquillet, were studied at Coimbatore, India. The life cycle of the midge was shorter in summer than winter: Johnson grass,Sorghum halepenseand pearl millet,Pennisetum americanumserved as alternate hosts for the sorghum midge. Seasonal incidence studies revealed that four peak infestations occurred in crops sown in April, June, August and October. Midge developmental stages were quite active all through the year with no diapause, Peak adult midge attraction to the light trap was recorded at 21.00 hours. However, adult midges were found to be quite active only in the daytime in the field. There was no relationship between adult midge catches from the light trap and the population recorded in the field. Morning relative humidity and wind velocity were negatively associated with the population of midge attracted to the light trap. An increased percentage of midge population was recorded in the light trap during the new moon and second quarter phases of moon. Sticky traps were not efficient in trapping adult midges. One pair of adult midge per earhead caused 16–9% grain damage.

ISSN:0143-6147    

DOI:10.1080/09670878509371000

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Notes given on taxonomic characters, and feeding injury symptoms of the four common thrips pestsFrankliniella schultzei(Trybom),Scirtothrips dorsalisHood,Megalurothrips usitatus(Bagnall) andCaliothrips indicus(Bagnall) can help in correct identification of groundnut Thysanoptera. A description ofThrips tabaciLind. is also included, this species being an important vector of tomato spotted wilt virus the world over, although not in India. Identification under field conditions can be made from specific injury symptoms;F. schultzeifeeding results in scars on young foliage, S.dorsalisinjury appears as light green patches on the upper surface of young foliage and brown necrotic areas on the lower surface of older leaves; andC. indicuscauses stippling on older leaves. Duration of egg incubation period forF. schultzei and S. dorsaliswas 6–8 days, of larval instars 6–7 days and prepupal and pupal stages 2–4 days. ForC. indicusthe duration of egg instar was slightly longer, 7–10 days, and was similar toF. schultzeiand S.dorsalisfor other development stages.C. indicusproduced many more progeny than the other two species.

ISSN:0143-6147    

DOI:10.1080/09670878509371001

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Treating rice seedlings with chemicals shortly before or after infestation controlled stem borer activity in the stems. The liquid formations were more effective for near immediate protection. There was a lag in the effectivity of the granular formulations shortly after application. The trial showed that two (Triazophos and Mocap applied at 0.75 and 1.00 kg a.i./ha, respectively) of the chemicals tested were effective after 7 days.

ISSN:0143-6147    

DOI:10.1080/09670878509371002

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The resistance ofAbelmoschus esculentus(L.) Moench to the leafhopper,Amrasca devastans(Dist.), was studied with reference to the hairiness of leaves. Resistant varieties had more and longer hairs on the midrib and lamina than the susceptible varieties. The number and length of hairs rather than the density influences plant resistance.

ISSN:0143-6147    

DOI:10.1080/09670878509371003

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A study of simulated rat damage was done to determine the loss of wheat yield when O (control). 10, 30 and 50% ot the wheat stems were cut at tillering, booting, dough and mature crop stages. The yields at harvest from each of 128 1‐m2plots were compared by analysis of variance and least significant difference tests. Yield at the tillering stages was not significantly different from the controls but yields at all other stages differed significantly. Yield losses in tillering and booting stages were not significant for the different damage levels except for 50% stem cutting at the booting stage. The yields from dough and mature crop stages at all damage levels were significantly lower than yields from controls. No significant differences in yield at all growth stages were observed between control plots and those receiving 10% damage, but 30 and 50% damage gave significant losses.

ISSN:0143-6147    

DOI:10.1080/09670878509371004

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The anticoagulant rodenticides bromadiolone (0.005%), brodifacoum (0.005%) and warfarin (0.025%) were tried for their efficacy against rodent pests in paddy fields around Tirupati, Andhra Pradesh, South India. Baiting with bromadiolone and brodifacoum for 3 days and warfarin for 10 days continuously gave 70, 74 and 66% control, respectively. Fumigation of the residual population using aluminium phosphide further enhanced the percentage control in warfarin‐treated units. It is suggested that both bromadiolone and brodifacoum, second generation anticoagulants, are more effective and economical for the control of field rodents than warfarin, a multiple dose anticoagulant rodenticide.

ISSN:0143-6147    

DOI:10.1080/09670878509371005

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

In India the area of land given to maize ranks fifth after rice, wheat, sorghum and pearl millet. In grain production maize holds fourth position over pearl millet. Of the 61 diseases of maize recorded so far, 15 and one nematode problem, are considered to constitute the major constraints limiting production. The major diseases are: four foliar diseases, two pre‐flowering and three post‐flowering stalk rots, four downy mildews and two sheath diseases. Information on ear, cob and kernel rots, smut and virus diseases is presented. An account of post‐harvest microbial problems is given. Four major approaches of disease management in the Indian context are outlined and the most appropriate one is considered to be host resistance. Adoption of this approach has yielded promising results for five major disease groups. It is pointed out that, so far, among the materials released which are resistant to one disease, or one set of diseases, most turn out to be susceptible to another set of diseases. The development of multiple resistance to the major diseases prevalent in the diverse agro‐ecosystems of India seems more appropriate. The population improvement approach through a recurrent selection scheme was adopted and since 1973, a high level of resistance to as many as 12 diseases has been developed. Although seven disease groups are amenable to chemical control, a very favourable cost: benefit ratio (1 : 14) is obtained only for seed and seedling groups of disease. Certain agronomic practices also help in reducing incidence of certain disease groups. The total estimate of loss in economic product per annum due to all diseases taken together has been estimated to be 13.2%.

ISSN:0143-6147    

DOI:10.1080/09670878509371006

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor