摘要:

Infection and yield loss induced by groundnut leaf spots were determined with benomyl during the 1989 and 1990 crop seasons under natural disease pressure in the field in Sierra Leone. Weather conditions in both years were highly favourable to leaf spot infection and development. In 1989 benomyl, applied at weekly intervals and at the rate of 0.15 kg a.i. ha−1for a total of 10 applications, effectively controlled leaf spots and increased both pod and haulm yields by 85%. An estimated potential pod yield loss of 46% was recorded, indicating the importance of the diseases as major constraints to groundnut production in Sierra Leone. In 1990, however, a higher level of leaf spots severity was observed causing extensive damage of the foliage. Benomyl, applied at bi‐weekly intervals and at the rate of 0.225 kg a.i. ha−1for a total of five applications failed to effectively control the diseases, increasing pod yield by only 27%.

ISSN:0143-6147    

DOI:10.1080/09670879209371645

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The insecticidal activity of neem,Azadirachta indicaA. Juss., was tested on two major cowpea pests using different concentrations of aqueous extracts, and powders of both neem seed and kernel. The pests were larvae ofMaruca testulalisGeyer (Lepidoptera: Pyralidae), the legume pod borer andClavigralla tomentosicollisStäl (Hemiptera: Coreidae), the cowpea coreid bug. Ife Brown, an improved local cowpea variety, and IT84S‐2246, a breeding line from IITA grain legume programme, were used in the study. Neem proved effective in acting as an insecticide and affected the rates of development of both pests at concentration as low asca.9% solution (wt/vol.). Imaginal survival was found to decrease with increasing neem concentration, but a point was reached where further increase in the amount of neem produced no significant changes in survival rates. Most bug nymphs died within 9 days of infestation but those which survived to adult in the 5% solution (wt/vol.) of the seed extract took almost twice the normal developmental time, and the emerging adults appeared weakened. While both the neem extracts and powder proved effective in suppressing development the former were more effective. This is the first report on the potential use of neem in the protection of cowpeas againstC. tomentosicollisandM. testulalis.

ISSN:0143-6147    

DOI:10.1080/09670879209371646

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Monitoring procedures with different trap designs and their proper location within the tree canopy were standardized forArchips pomivoraMeyrick, a predominant tortricid infesting apple in Himachal Pradesh. Two synthetic pheromonal lures OBLR and FTLR were used over three seasons (1982–1984). Trap design had no significant influence on moth catch. Trap placement in the tree canopy was an important factor influencing the magnitude of moth catch. Traps positioned in the upper half of the canopy and near the periphery attracted significantly more moths. This pattern remained consistent in both smaller (<4.0m) and taller (>7.0m) trees. Almost all the moths were captured within the canopy, and traps placed outside attracted very few moths.

ISSN:0143-6147    

DOI:10.1080/09670879209371647

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The pepper weevil,Anthonomus eugenii Canowas found to feed, oviposit, and complete its larval development in the fruit and/or flowers of a number ofCapsicumandSolanumspecies. Several of these plants, including S.americanum(American black nightshade), S.pseudogracile, S. eleagnifolium(silverleaf nightshade) and S.carolinense(horse‐nettle) are found in Florida and other pepper‐growing regions of the US and possibly can serve as alternative hosts for the pepper weevil. The pepper weevil was found to complete its development in pepper flowers in addition to the fruits, although more eggs were deposited in pepper fruit than in flowers. Oviposition in American black nightshade flowers was not observed. The development time of the pepper weevil from egg to adult in bell pepper and American black nightshade fruit kept at 25.7–27.7°C was about 14 days.

ISSN:0143-6147    

DOI:10.1080/09670879209371648

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

An experiment was conducted in Kitale, Kenya in 1987 to obtain information on pheromone traps and lures for a monitoring system for the maize stalk borer,Busseola fusca(Fuller). Several factors potentially affecting the catch of maleB. fuscaadults were evaluated. A trap's location in the field had the greatest impact on moth catch, with traps located near field edges catching more maleB. fuscathan traps located further within the field. Of the two trap types evaluated, net traps caught significantly (P < 0.01) more maleB. fuscamoths than water traps. The most moths were captured with lures containing the highest loading rate. In addition, the overall trend of our results suggests that loading rates greater than 9 mg, the highest rate tested in this study might result in even larger moth catches. The effect of the amount of time a lure remained in the field on the number of maleB. fuscamoths captured was examined using simple linear regression and a significant relationship was observed (y = 0.380–0.0023x; r2= 0.76). Although moth capture declined slightly, the female sex pheromone ofB. fuscawas quite stable under Kitale field conditions. Lures continued to attract male moths for at least a 9‐week period and remained effective for over a year when stored in a refrigerator.

ISSN:0143-6147    

DOI:10.1080/09670879209371649

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Daily rhythms of feeding, attraction to light and female calling ofAgrotis segetum, Mentaxia ignicollis, Heliothis armigera, Mythimna loreyiandPlusua orichalceaare described. The periods of feeding activity and female calling are typical for all the species. The male/female ratio during the copulation period is shifted in favour of males, and the biological significance of this is discussed.

ISSN:0143-6147    

DOI:10.1080/09670879209371650

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Seventy‐one identified, exotic,B. thuringiensisstrains, representing 31 H‐serotypes and 150 locally isolatedB. thuringiensisstrains, were screened for activity against second‐instarC. partelluslarvae. Differences in the toxicity of different subspecies toC. partelluslarvae were revealed in the screening tests. Bio‐assays were performed on selected, toxicB.thuringiensisstrains, and varietiesentomocidus, kenyaeandkurstaki(obtained from the USDA collection) were found to be the most potent strains tested, having calculated LC50values of 2.00 x 105, 5.10 x 105and 6.30 x 105colony‐forming units per gram (c.f.u./g) of artificial diet respectively. The results further highlighted the differences in the activity of differentB. thuringiensissubspecies, and showed that there was variation in the potency of strains within the same subspecies. Thus the origin of the strain appears to affect its toxicity to a particular target species. A number of highly toxicB. thuringiensisisolates were recovered from soils, insect frass and dead insect material collected in Kenya. Isolates A‐3, B1–1, A‐C‐2 and L1–6, recovered from deadHeliothis armigeralarvae and insect frass, were the most potent strains recovered, with respective LC50values of 7.00 x 104, 1.70 x 105, 2.30 x 105and 2.60 x 105c.f.u./g of artificial diet. These strains are therefore excellent candidates for use in a control programme againstC. partellus.

ISSN:0143-6147    

DOI:10.1080/09670879209371651

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The granular insecticides were evaluated for their efficacy against groundnut leaf miner,Aproaerema modicellaDeventer, under rainfed conditions by applying them to the soil along with fertilizers at the time of sowing. Among eight insecticidal treatments, four treatments, namely, isofenphos 5 G (2 kg a.i./ha), carbosulfan 10 G (4 kg a.i./ha), isofenphos 5 G (5 kg a.i./ha) and phorate 10 G (4 kg a.i./ha) were found significantly more effective in suppressing the leafminer infestation. These treatments also gave increased pod yields compared with other treatments including check. The activity of natural enemies such as insect parasites and pathogens was not affected by these insecticidal treatments.

ISSN:0143-6147    

DOI:10.1080/09670879209371652

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Modifications were made in a diet reported in the literature for rearing the spiny bollworm,Earias insulana(Boisduval), a major pest of cotton and okra, in India, with an objective of obtaining reproductively competent adults. Out of the six diets evaluated, two modified diets were found to be nutritionally adequate to produce adults with a satisfactory reproductive performance (about 165 eggs per female with more than 90% viability). These two diets contained maize semolina, wheat bran, wheat germ oil, brewer's yeast, salt mixture, ascorbic acid, agar and distilled water in prescribed proportions. In addition to these ingredients one diet contained soybean powder and vitamin mixture, whereas the other contained decorticated glandless‐cotton seed powder. Data are presented on the development and reproductive performance of the insects reared on these two diets for three successive generations.

ISSN:0143-6147    

DOI:10.1080/09670879209371653

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The population growth pattern of the cassava mealybugPhenacoccus manihotiMat‐Ferr was studied over two population cycles of the pest in Freetown, Sierra Leone. The numbers and rate of dispersal of the insect were higher and the damage it produced more severe in the dry season than in the rainy season. During the rainy season the mealybug population consisted mainly of adults. Even though rain is an important known abiotic natural control factor for the pest the decline in the insect's numbers started before the rainy season. This was attributed to reduction in the carrying capacity of the habitat. The indigenous natural enemies adopted the pest as a food source but did not control its population growth. The other mealybugs observed on the crop,P. madeirensis(Green) andFerrisia virgata(Cockerell) were economically insignificant.

ISSN:0143-6147    

DOI:10.1080/09670879209371654

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor