Showing papers in "International Journal of Tropical Insect Science in 1988"
TL;DR: A distribution map, tables of alternate host plants, outbreaks, resistant rice varieties, resistant wild rices, natural enemies and developmental stages, and a brief description of current status of the leaffolders are provided.
Abstract: This bibliography on rice leaffolders contains 886 published and unpublished references for the period 1854 to June 1987. References are arranged alphabetically by the name of author and also classified by subjects. A distribution map, tables of alternate host plants, outbreaks, resistant rice varieties, resistant wild rices, natural enemies and developmental stages, and a brief description of current status of the leaffolders are also provided.
88 citations
TL;DR: During the two years research 1983–1985 on traditional maize granaries in Togo, three methods for loss assessment which are discussed by the FAO were studied: the count and weigh method, the standard volume/weight method and the thousand-grain mass method.
Abstract: During the two years research 1983–1985 on traditional maize granaries in Togo, we studied three methods for loss assessment which are discussed by the FAO: the count and weigh method, the standard volume/weight method and the thousand-grain mass method. In general, between 80 and 90% of the overall losses were caused by insect feedings. Besides Prostephanus truncatus (Horn), the most important storage pests were Sitophilus zeamais (Motsch.), Tribolium spp. and Cathartus quadricollis (Guer.). Best results were given by the count and weigh method. The significantly highest losses of dry weight (12–13%) were found after 6 months in stored hybrids. At the same time, local varieties appeared much more adapted to traditional storage methods, exhibiting losses of only 3% under the same conditions. Lowest level of losses (< 1%) were observed in regularly smoked granaries in the mountain regions. The mean losses of dry weight during primary season were found to be 6.4% after 6 months, while after a storage period of 4 months during the secondary season, losses were as high as 8%. In Togo, P. truncatus was observed for the first time in spring 1984. Because of the different damage P. truncatus causes on corn, a newly developed sample weight method was examined in an additional test. After 6 months of observation, this dangerous pest caused serious losses up to 30.2%.
68 citations
TL;DR: The results indicate that 4-cresol and 3-n-propylphenol are the most important components for the of the attractancy phenolic mixture.
Abstract: Seven phenolic compounds (phenol, 3- and 4-cresols, 3- and 4-ethylphenols, and 3- and 4-n-propylphenols) previously shown to be components of a fraction of an extract of buffalo urine which was active as a tsetse attractant, were evaluated in field experiments, individually at different concentrations, and in blends. The results indicate that 4-cresol and 3-n-propylphenol are the most important components for the of the attractancy phenolic mixture.
62 citations
TL;DR: Several important factors like Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus, have developed resistance for which agricultural treatments cannot be held responsible, and the rise in malaria in certain countries is only due to the increase of insecticide in agriculture after the “green revolution”.
Abstract: Agricultural treatments mainly against cotton and rice pests put a considerable insecticide pressure on larvae and sometimes adults of several vector species. Resistances to compounds which had never been used for public health, but were currently employed in agriculture were observed among vectors. It was also noticed that resistance level in some vector species was linked to the quantity of the compound used in the same area against crop pests. Resistance in Anopheles gambiae in Africa, in An. albimanus in Central America, in An. culicifacies and An. aconitus in South East Asia, in An. sacharovi in Turkey, in Culex tritaeniorhynchus in the Far East as well as the DDT resistance in Simulium damnosum in West Africa, seem to be associated with the agricultural practices. On the other hand, resistance did not develop in species which, due to their ecology, were not in contact with agricultural insecticide even in areas where DDT was applied for more than 20 years in house spraying. This is the case of An. dirus and An. minimus in Thailand and An. darlingi South America. However several important factors like Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus, have developed resistance for which agricultural treatments cannot be held responsible. It would be worth saying that the rise in malaria in certain countries, such as India, is only due to the increase of insecticide in agriculture after the “green revolution”.
45 citations
TL;DR: The work that has been done on the biology and control of this pest at the International Institute of Tropical Agriculture (IITA) is briefly discussed with emphasis on the development of a management strategy centred around host plant resistance.
Abstract: The legume pod-borer, Maruca testulalis, continues to be a major limitation to successful cowpea cultivation in many countries. During the past decade, research on this insect has increased in scope and intensity at international agricultural research centres and a number of universities. The work that has been done on the biology and control of this pest at the International Institute of Tropical Agriculture (IITA) is briefly discussed with emphasis on the development of a management strategy centred around host plant resistance, and some suggestions for future research direction are given.
43 citations
TL;DR: A multi-donor funded control and containment campaign, co-ordinated by FAO, has been in operation in Tanzania since 1984 and is comprised of a training element for agricultural staff and several field extension campaigns which assist with insecticide distribution and with dissemination of information to farmers.
Abstract: Since it was first reported in Tanzania in 1981 the Larger Grain Borer (LGB) has spread from a small area in the northwest of the country to 17 of the 20 regions. Only in the extreme south, along the Mozambique border, has the pest not been found. It has also become established in Kenya, Burundi, Togo and Benin. LGB can cause very high weight loss in farm stored maize and dried cassava, commodities on which it if able to breed. After 5 months storage during the dry season in western Tanzania, mean losses of 9% were found, a much higher level than losses of less than 1 % which would be expected in LGB-free areas in East/Central Africa. Application of 0.5% permethrin dust at 2.8 ppm provides excellent protection against LGB when applied to loose maize grain for 1 year. However, the storage of shelled maize predisposes towards the development of Sitophilus species which can result in high losses being sustained. A ”cocktail“ of permethrin and pirimiphos-methyl, applied at 3.3 and 17.7 ppm respectively, successfully controls all storage pests and is currently being used in an extensive control campaign in Tanzania. A multi-donor funded control and containment campaign, co-ordinated by FAO, has been in operation in Tanzania since 1984. The programme is comprised of a training element for agricultural staff and several field extension campaigns which assist with insecticide distribution and with dissemination of information to farmers. The primary objectives of the programme are to reduce farm storage losses and to contain LGB within the areas it is now found. In some regions, where LGB is relatively isolated, attempts are being made to eradicate it.
38 citations
TL;DR: Indirect estimates using pesticides are more common and indicate that an integrated pest management approach to soil pests is required, and methods are presented here for termites and maize which could be adapted for other pests and crops.
Abstract: Soil pests are defined as those in which the damaging stage of the life cycle lives in the soil. In Africa the most important soil insect pests are termites, followed by the larvae of various beetles (particularly scarabs), and by millipedes which are included here as they damage plants in a similar way to some insects. The most important cereals in Africa are maize, sorghum and millet, with wheat and rice increasing in importance. Attack by soil pests usually begins on the root system and yield losses result from plant mortality, lowered translocation of water and nutrients, increased susceptibility to pathogens, or lodging with subsequent damage to grain on the ground from various vertebrates, invertebrates and saprophytes. Data have often been presented as ”percentage of plants damaged“ or ”infested” and bear little relationship to yield loss, as this depends on the severity and timing of attack. A succession of soil pests can attack the plants from seedling to maturity. Early season attacks can result in compensatory growth by remaining plants leading to overestimation of yield loss by simple estimates of plants damaged. Direct estimation of yield loss is time-consuming and few such studies have been made. However, methods are presented here for termites and maize which could be adapted for other pests and crops. Indirect estimates using pesticides are more common and, in general, indicate that an integrated pest management approach to soil pests is required.
37 citations
TL;DR: Guava leaves were more toxic for both species than eucalyptus leaves, and both test materials at 15 g/100 g depressed the progeny development of the test insects.
Abstract: Sun-dried guava ( Psidium guajava L.) and eucalyptus ( Eucalyptus globulus L.) leaves were evaluated as repellent and toxic materials against the rice weevil, Sitophilus oryzae L., and the granary weevil, Sitophilus granarius L. under laboratory conditions. LC 50 values of sun-dried guava and eucalyptus leaves admixed with rice grains against S. oryzae were 2.251 and 4.140g leaves/100g rice grains, respectively, while they were 2.278 and 4.857 g leaves/100 g rice grains in the case of S. granarius , respectively. Guava leaves were more toxic for both species than eucalyptus leaves. Eucalyptus leaves were more repellent than guava leaves. Both test materials at 15 g/100 g depressed the progeny development of the test insects.
37 citations
TL;DR: Three neem products were applied on field cassava for protection against damage by the grasshopper, Zonocerus variegatus, andfficacies of NOEC and NKWE were superior to insecticides.
Abstract: Three neem products—an emulsifiable concentrate of neem oil (NOEC), neem kernel water extract (NKWE) and neem leaf water extract (NLWE)—were applied on field cassava for protection against damage by the grasshopper, Zonocerus variegatus (L.). Three conventional insecticides viz. lindane 0.3%, Cypermethrin 0.006% and monocrotophos 0.24% were also compared. All the neem products protected cassava for varying periods. Efficacies of NOEC and NKWE were superior to insecticides. From the results, neem products recommended to check the grasshopper damage were as follows: NOEC 0.5–2% to be applied every 8 days, NOEC 3–4% to be applied every 10 days, NKWE 7–10% to be applied every 12 days, NLWE 50% to be applied every 6 days.
35 citations
TL;DR: The number of prey consumed daily by each predator stage tested, increased more steeply at lower, than at higher prey densities, exhibiting thus the Type II functional response.
Abstract: The density responsiveness of larvae and adults of Cheilomenes lunata (Fabricius) preying on Aphis craccivora Koch was investigated under laboratory conditions where temperature and relative humidity were uncontrolled and fluctuated between 24-30°C and 43-90% respectively. The feeding rates of C. lunata were positively correlated with the population density of prey. The number of prey consumed daily by each predator stage tested, increased more steeply at lower, than at higher prey densities, exhibiting thus the Type II functional response. Fecundity of C. lunata females also increased to a plateau with increasing prey density.
34 citations
TL;DR: In southern India, the principal tea pests such as the mites, Acaphylla theae, Calacarus carinatus and Oligonychus coffeae; the thrips, Scirtothrips bispinosus; the aphid, Toxoptera aurantii; and the caterpillars, Caloptilia theivora, Homona coffearia and Cydia leucostoma are attacked by many natural enemies.
Abstract: In southern India, the principal tea pests such as the mites, Acaphylla theae, Calacarus carinatus and Oligonychus coffeae; the thrips, Scirtothrips bispinosus; the aphid, Toxoptera aurantii; and the caterpillars, Caloptilia theivora, Homona coffearia and Cydia leucostoma are attacked by many natural enemies. H. coffearia is efficiently controlled by the ichneumonid, Phytodietus sp., and the tachinid, Palexorisla solennis, whilst the eulophid, Sympiesis dolichogaster, affords excellent regulation of C. theivora. The braconid, Apanteles aristaeus, is the chief parasitoid of C. leucostoma, but the efficiency of this species is rather low. The aphiidids, Aphidius colemani, Lipolexis scuttellaris and Trioxys indicus, and several species of coccinellids and syrphids exert tremendous influence on the populations of T. aurantii. No natural enemies of the scolytid stem borer, Xyleborus fornicatus, could be recorded. For the management of mites, pesticides are applied regularly and the widespread usage of broad spectrum acaricides such as dicofol and sulphur is an important reason for the low incidence of predatory mites in tea fields.
TL;DR: This study describes the various methods of assessing and quantifying the on-farm (pre-harvest) yield losses caused by the above insect pests.
Abstract: In many parts of Africa, field sorghum is attacked by a number of insect pests, notable among them being the sorghum shootfly, a range of lepidopterous stem borers, midge and a complex of head bugs. Studies on yield losses caused by these insects are scanty, yet such information is essential in formulating an IPM strategy for the crop. This study, therefore, describes the various methods of assessing and quantifying the on-farm (pre-harvest) yield losses caused by the above insect pests.
TL;DR: All species were equally tuned to the four odour substances, which indicates that these odours do not determine host Specificity in Glossina palpalis gambiensis.
Abstract: A comparison was made of the EAG responses of repleted males and females of Glossina palpalis gambiensis Vanderplank, G. tachinoides Westwood, G. fuscipes fuscipes Newstead, G. morsitans morsitans West wood and G. austeni Newstead to the odour of various concentrations of acetone, 4-heptanone, 3-nonanone and l-octen-3-ol. The stimulatory effectiveness of these substances increased in the order: acetone < 4-heptanone < 3-nonanone < 1-octen-3-ol. Amounts of acetone 103–104 times greater and of 4-heptanone and 3-nonanone 10–100 times greater than those of l-octen-3-ol were required to obtain similar EAG responses. These results are discussed in relation to the behavioural effects of the odours of these substances on tsetse in wind tunnel experiments in the laboratory and catching experiments in the field. In G. m. morsitans and G. tachinoides, the EAG responses of males were somewhat higher than those of females. In G. austeni, G. f. fuscipes and G. palpalis gambiensis, however, the reverse occurred. All species were equally tuned to the four odour substances, which indicates that these odours do not determine host specificity.
TL;DR: The potential egg production and egg viability of the potato tuber moth, Phthorimaea operculella (Zell.) was significantly towered when moths of either sex were exposed in 250 ml glass jars to vapours of orange peel oil emanating from 160 μ oil.
Abstract: The potential egg production and egg viability of the potato tuber moth, Phthorimaea operculella (Zell.) was significantly lowered when moths of either sex were exposed in 250 ml glass jars to vapours of orange peel oil emanating from 160 μ oil. Oviposition and egg hatching was totally inhibited when female moths of both sexes were exposed to 220 μl of the oil.
TL;DR: The efficacy of the powder and volatile oil of Piper guineense Schum & Thonn at protecting cowpea against seed beetle, Callosobruchus maculatus was tested in the laboratory and at low concentrations the powder significantly reduced oviposition and adult emergence while Oviposition was completely suppressed at a higher concentration of 42%.
Abstract: The efficacy of the powder and volatile oil of Piper guineense Schum & Thonn at protecting cowpea against seed beetle, Callosobruchus maculatus (F.) was tested in the laboratory. At low concentrations the powder significantly reduced oviposition and adult emergence while oviposition was completely suppressed at a higher concentration of 42%. The same concentration provided adequate protection for the same amount of cowpea placed in containers of different volumes. The powder, however, did not show any fumigant effect. Volatile oil at 0.002 and 0.005% significantly reduced oviposition and adult emergence, while oviposition was completely suppressed at 0.02% and above. Weight loss of seeds at 90 days after treatment with volatile oil decreased as concentration of the oil increased. The practical significance of the results in small scale storage of cowpea is discussed.
TL;DR: Results revealed that if the NPV is used to control termites, periodic applications would be more efficacious than one treatment.
Abstract: A nuclear polyhedrosis virus isolated from the Egyptian cotton leafworm, Spodoptera littoralis, was found to infect termite castes of Kalotermes flavicollis. Laboratory studies indicated that no specific trend toward mortality responses among the different individuals of termites was noted. All test castes of termites, young, middle-sized, old and reproductive nymphs, and soldiers, were quite equal in their response to the virus infection, regardless of whether the virus concentration was high or low; a concentration of 6.4 × 108 polyhedra/ml, killed only 64% of the treated individuals, while the dosage of 6.4 × 107 polyhedra/ml produced over 90% mortality. Also, the same trend of response was recorded with the survivors which received challenge doses of NPV suspension each 9 or 10 days. On the other hand, these results revealed that if the NPV is used to control termites, periodic applications would be more efficacious than one treatment. Virus symptoms were recorded in all affected insects.
TL;DR: The susceptibility to poisoning of adult insects by these pyrethroids (except bioresmethrin) was increased by cotreatment with profenofos or with piperonyl butoxide (PBO).
Abstract: The insecticide activity of synthetic pyrethroids to Triatoma infestans was tested by topical application. Deltamethrin, fenpropathrin, bioresmethrin, permethrin, cypermethrin, d-phenothrin and cyphenothrin showed the highest activity.The susceptibility to poisoning of adult insects by these pyrethroids (except bioresmethrin) was increased by cotreatment with profenofos or with piperonyl butoxide (PBO). Assayed pyrethroids synergized by PBO showed similar general structure.The vinyl cyano pyrethroids showed a knockdown effect with a delayed recovery. During 15 days after intoxication with deltamethrin, insect recovery was observed. Recovery blockage by PBO was observed in cyphenothrin and deltamethrin poisoning at low doses.
TL;DR: Attacks are low during the early growth phase of the rice plants and increase gradually to reach spectacular levels between 70 and 90 days after transplantation, after which there is decreased attack.
Abstract: Des travaux ont ete conduits sur deux annees consecutives (1983 et 1984) en riziculture irriguee dans le Sud-Ouest du Burkina Faso, afin de suivre l’evolution saisonniere des infestations de la cecidomyie du riz, Orseolia oryzivora H. et G. sevissant particulierement dans cette zone du pays. L’evolution des attaques est semblable quelque soit la date de mise en place du riz au cours de la saison humide. Faibles en debut de cycle du riz (0 a 3% de “tubes d’oignon”), les infestations augmentent progressivement pour atteindre des taux spectaculaires (20 a 55% de “tubes d’oignon”) entre 70 et 90 jours apres le repiquage, puis baissent en intensite. L’importance du parasitisme affectant la population larvaire du ravageur a ete etablie; des taux de 77% de larves parasitees ont ete enregistres. Cependant ce parasitisme du essentiellement aux deux microhymenopteres, Platygaster diplosisae Risb. et Tetrastichus paehydiplosisae Risb., s’installe tardivement. Ces resultats marquent une etape dans la mise au point d’une strategie de lutte integree sur les perimetres rizicoles irrigues au Burkina Faso.
TL;DR: Damage caused by Sylepta derogata (F), defoliator of okra, was less in plots treated with 5, 10 and 20% aqueous-methanol extracts of defatted neem cake, and neem seed cake applied as dust enhanced cowpea yield.
Abstract: Field trials of various neem formulations were conducted to determine their effectiveness for the control of some major pests of eggplant, Solanum melogena (L), okra, Hibiscus esculentus (L) and cowpea, Vigna unguiculata (L), Walp. Various concentrations of neem emulsion reduced incidence of Selepa docilis (Butler), Urentius sp. and Zonocerus variegatus (L), on eggplant. Damage caused by Sylepta derogata (F), defoliator of okra, was less in plots treated with 5, 10 and 20% aqueous-methanol extracts of defatted neem cake. Moreover, neem seed cake applied as dust enhanced cowpea yield.
TL;DR: The results indicate that the practice of mixed cropping beans with cowpeas confers no advantage to either crop with respect to attack by M. sjostedti, and the inclusion of a non-host plant (maize) in the mixture, significantly reduces infestation.
Abstract: The effect of growing cowpeas mixed with either beans or maize on population densities of Megalurothrips sjostedti (Trybom) was investigated. Also investigated was the effect of varying the cropping densities of the host plants on the pest populations.There was a significantly lower population of M. sjostedti in cowpea/maize, bean/maize, and cowpea/bean/maize mixed stands as compared with that in either cowpea/bean stands or monoculture stands of cowpeas and beans. Increasing the cropping densities of the host crops increased the abundance of the pest in non-maize based mixed stands, but this effect was not observed in the maize-based mixed stands.The results indicate that with regard to infestation by M. sjostedti, the practice of mixed cropping beans with cowpeas confers no advantage to either crop with respect to attack by M. sjostedti. On the contrary, combining the two crops attracted infestation levels similar to those attracted by either crop grown in monoculture. But the inclusion of a non-host plant (maize) in the mixture, significantly reduces infestation.
TL;DR: Various storage techniques are described and discussed against the background of available information on storage losses and with regard to the common patterns and periods of storage in Africa at the farm level and in ”centralized“ storage.
Abstract: Storage method encompasses the patterns and periods of storage as well as particular storage techniques. Storage management is therefore a major determinant of post-harvest losses in stored cereals: affecting the magnitude of losses and their susceptibility to reduction. Key issues are the location and scale of grain storage which, in most developing countries, involves both rural domestic storage and larger scale ”buffer“ storage at district centres, commonly near towns.
TL;DR: Different concentrations of essential oil of lemon grass, Cymbopogen citratus, were tested for their ovipositional inhibition, antifeedant activity and insecticidal properties against the lesser cotton leafworm, Spodoptera exigua.
Abstract: Different concentrations of essential oil of lemon grass, Cymbopogen citratus, were tested for their ovipositional inhibition, antifeedant activity and insecticidal properties against the lesser cotton leafworm, Spodoptera exigua. The results obtained showed that 2% concentration of oil emulsion inhibited egg laying and 0.5% concentration more than reducted by 70% the number of eggs deposited on oviposition sites. 2% concentration acts as a protective concentration against the immature stage by hindering the third instar larvae to feed on treated leaf discs. In addition, the oil emulsion was insecticidal in that percentage mortality was directly proportional to the concentration applied and to the duration of exposure. Older egg masses were more affected by treatment than the newly laid eggs. 2% concentration inhibited hatchability when sprayed on egg masses before hatching. Lemon grass oil effectively controlled 5. exigua as an ovicidal and larvicidal agent.
TL;DR: Tests with Beauveria bassiana, isolated from lepidopteran pests, have shown that the mite is susceptible to this fungus, and laboratory bioassays have given mite mortality up to 60%, indicating the possibility of utilizing some of these pathogens in mite control.
Abstract: Preliminary investigations have shown the presence of pathogenic fungi in natural populations of the cassava green spider mites. Among others, Entomopthora sp and Hirsutella sp were isolated from dead mites sampled from the field. Laboratory bioassays have given mite mortality of up to 60%, indicating the possibility of utilizing some of these pathogens in mite control. Tests with Beauveria bassiana, isolated from lepidopteran pests, have also shown that the mite is susceptible to this fungus.
TL;DR: A higher proportion of adult emergence was usually associated with the group of mummies passed at 12–15°C before storage and practically good emergence was recorded even if the mummies were stored for a month at 4°C if kept at 12-15°Cs for 72 hr prior to storage.
Abstract: Trials for cold storage of the mummies of Aphis craccivora Koch parasitized by Trioxys indicus Subba Rao & Sharma were made. Newly formed mummies having fourth instar larvae of the parasitoid were put either at 20–25°C or at 12–15°C, 10 hr photoperiod for 24–72 hr before storage inside the refrigerators (4–8°C) for 10–40 days. A higher proportion of adult emergence was usually associated with the group of mummies passed at 12–15°C before storage and practically good emergence was recorded even if the mummies were stored for a month at 4°C if kept at 12–15°C for 72 hr prior to storage.
TL;DR: Results of these laboratory studies and those of field observations suggest that mature soybean seeds are the most important food source in the seasonal phenology of M. parvus.
Abstract: Laboratory studies with Megalotomus parvus (Hemiptera: Alydidae), feeding on seeds or pods of legumes, and on different parts of the soybean plant, Glycine max, demonstrated that nymphal survivorship, developmental time and body weight at adult emergence, and adult reproductive parameters, survivorship, longevity and body weight changes, exhibited differences depending on the food source utilized. In general, mature soybean seeds (R8 stage) were the most suitable food. The greatest nymph and adult survivorship and the greatest adult longevity were obtained from this food source. Body weight at certain ages and fecundity of females was also greater on mature soybean seeds than on the other foods. Immature soybean seeds for nymphs, and soybean pods for adults, were the second most suitable food, followed by green beans, Phaseolus vulgaris and immature lupin, Lupinus luteus seeds (for nymphs) and lupin pods (for adults); nymph and adult performance was drastically reduced on lupin seeds/pods and no nymphs survived to adult on soybean stems or leaves. On all foods tested, duration of the nymphal stages differed significantly, with the first stage being the shortest, and the fifth the longest. Females achieved significantly greater body weight than males on all foods, except on lupin pods. Results of these laboratory studies and those of field observations suggest that mature soybean seeds are the most important food source in the seasonal phenology of M. parvus
TL;DR: The results revealed that powders of pomegranate peel, guava leaves and lemon grass, greatly affected the insect development in terms of larval duration, larval and pupal weights, deformities in pupae and moths, percentage of emergence, egg production and hatching.
Abstract: Investigations have been made to evaluate the development of Spodoptera littoralis as affected by feeding on a standard artificial diet containing powder of some plant species known to be resistant to the infestation of this insect. Trials were also made to find out whether the effect of these plants facilitate the potency of Bacillus thuringiensis var enlomocidus HD-635 vs. the target insect. The results revealed that powders of pomegranate peel, guava leaves and lemon grass, greatly affected the insect development in terms of larval duration, larval and pupal weights, deformities in pupae and moths, percentage of emergence, egg production and hatching. This may be correlated to the chemical constituents of these plants. A marked increase was observed in the potency of B. thuringiensis endotoxin preparation vs. S. littoralis when combined with some of the tested powdered plants or its extracts but in varying degrees.
TL;DR: It was evident from day-to-day changes that protein, RNA and DNA in ovary followed a specific individual pattern of changes during the developmental period under study, and ovarian weight and egg number increased with different doses of the vitamin.
Abstract: The effects of cyanocobalamin on the protein, RNA and DNA contents of ovary of silkworms, Bombyx mori L., were investigated. Two sets of experiments were performed, one set dealing with the changes on some selected days in protein, RNA and DNA contents after a single injection of different doses of cyanocobalamin (0.25, 0.5, 1, 2 and 5 μg/g of body weight), given on 2nd day of fifth larval instar (day 0), and the other dealing with the day-to-day variations of these cellular constituents and the effect of a particular dose (2 μg/g) of cyanocobalamin on the daily changes of the substances. In the first set of experiments, the enhanced protein content of ovary over the control value was found on day 8 (2nd day of pupa) and day 13 (adult stage) with 1, 2 and 5 μg of cyanocobalamin/g. Cyanocobalamin at the dose of 0.25 and 0.5 μg was ineffective in causing any change in protein content. Increased RNA content was noted in comparison to the control on days 3 (5th day of fifth instar), 8 and 13. In case of DNA content of ovary, the enhancement was observed on days 8 and 13 with 1, 2 and 5μ/g doses. It was further evident from day-to-day changes that protein, RNA and DNA in ovary followed a specific individual pattern of changes during the developmental period under study. Cyanocobalamin at the dose of 2 μg/g increased protein content of ovary from day 5 to day 13, RNA content from day 3 to day 13 and DNA content from day 4 to day 13 without altering the specific pattern of variation of these cellular constituents. It was further observed that ovarian weight and egg number increased with different doses (0.5–5 μ/g) of the vitamin.
TL;DR: The termite Macrotermes herus builds domed earth mounds with no external openings and there is no specialized ventilation system in the mound, unlike those of other Macroterme species.
Abstract: The termite Macrotermes herus builds domed earth mounds with no external openings. The internal structure is described here. There is no specialized ventilation system in the mound, unlike those of other Macrotermes species.
TL;DR: The authors' findings suggest that in the cowpea cultivars studied, phenols in addition to the tough pod wall may be more important in conferring resistance to PSBs.
Abstract: Six cowpea cultivars, TVu 1890, TVu 1, TVx 3343-03E, IT82E-9, VITA-3 and Ife Brown, with different responses to infestation and damage by pod-sucking bugs (PSBs) were studied for the biophysical and biochemical characteristics of pod that may be involved in this differential response to feeding by PSBs. Tough pod wall, requiring a force of 25 newtons/mm2 to penetrate at pod maturity, is considered to be an important factor contributing to the lesser PSB feeding damage observed in the cultivar TVu 1890. The phenolic content of the pods of the studied cowpea cultivars was not correlated with their tannin content. Furthermore, no correlation could be established between the tannin content in the pod and the level of susceptibility of the cowpea cultivars to infestation and damage by PSBs. While tannins are considered to be important in conferring certain types of anti-herbivory properties to a number of plants and crop varieties, our findings suggest that in the cowpea cultivars studied, phenols in addition to the tough pod wall may be more important in conferring resistance to PSBs.
TL;DR: The effects of climate on the diurnal biting pattern of Simulium damnosum s.s. were measured at Jos Plateau, Nigeria, where rain in the hours prior to the catch inhibited morning activity by lowering the temperature and light intensity, and raising the humidity.
Abstract: The effects of climate on the diurnal biting pattern of Simulium damnosum s.s. were measured at Jos Plateau, Nigeria. Rain in the hours prior to the catch inhibited morning activity by lowering the temperature and light intensity, and raising the humidity. Under shade there were no remarkable fluctuations in the light intensity, and no obvious peaks in activity; in sunny places, activity was bimodal, with a small morning peak and a pronounced afternoon one. The fastest changing climatic factor relative to an increase in the biting activity of flies was light intensity; followed by temperature.