Bio-activities of Powders four plants against Prostephanus truncatus Horn. (Coleoptera: Bostrichidae) and Tribolium Castaneum Herbst (Coleoptera: Tenebrionidae)

The effect of the dry powders of the roots and leaves of Ocimum canum, Zanthoxylum xanthoxyloides, Moringa oleifera and Securidaca  longipedunculata on the survival of Prostephanus truncatus (Horn)  (Coleoptera: Bostrichidae) and Tribolium castaneum Herbst (Coleoptera:  Tenebrionidae) was determined in the laboratory. Generally, all the plant  materials exhibited various levels of bio efficacies, with Z. xanthoxyloides and S. longipedunculata exhibiting the highest potency. Percentage survivorship of 35% and 40% were recorded for the roots and leaves, respectively, of Z.  xanthoxyloides against T. casteeneum while 20% and 30% were recorded for roots and leaves of S. longipedunculata, respectively, against P.tuncatus

Indigenous fungal entomopathogens associated with the oil palm leaf miner Coelaenomenodera lameensis Berti and Mariau in Ghana

Background and Objective: The oil palm leaf miner Coelaenomenodera lameensis (Coleoptera: Chrysomelidae) is the most devastating insect pest of the African oil palm Elaeis guineensis Jacquin. Like most insect control programmes, control in Ghana has been through the use synthetic insecticides. The over-dependence on chemical control has brought in its wake adverse effects such as toxicity to the user and non-targeted organism. Entomopathogens have proven to be effective in the management of many insect species and these are environmentally-friendly. In this study we investigated reports by field workers of Council of Scientific and Industrial Research (CSIR)-Oil Palm Research Institute of Ghana who observed the presence of mycelia on the cuticle of cadavers of C. lameensis in their daily phytosanitary surveillance.Methodology and Results: Field surveys were conducted in three oil palm plantations viz: CSIR-Oil Palm Research Institute and a commercial oil palm farm, both at Kusi in the Eastern Region, and Twifo Oil Palm Plantation of Unilever Ghana Limited at Twifo Praso in the Central Region of Ghana to collect cadaver of C. lameensis infected with fungi. The cadavers were aseptically cultured in the laboratory on Potato Dextrose Agar and fungi isolated and identified. A total of 17 fungal species were isolated from cadavers of the leaf miner. These include Aspergillus sp, Metarhizium sp, Paecilomyces sp, Penicillium sp, Pestalotia sp, Rhizoctonia sp, and three unidentified species. Bioassays conducted to ascertain the pathogenicity of the fungi against C. lameensis adult showed an overall mortality ranging between 12.5% - 77.5% within 7 days. Growth of mycelia on treated dead insects ranged from 0% - 47.5%. The unidentified fungus coded BKFF was found to be the most lethal inducing about 77% mortality in the insect and thus more entomopathogenic, followed by Paecilomyces sp. (Ioprik31 and Pestalotia sp. (CKFF) (both 65%) whilst Rhizoctonia sp was found to be the least lethal.Conclusion and application of findings: This study presents important naturally occurring fungal species associated with the oil palm leaf miner C. lameensis in the field which famers can utilize as a control option upon further field studies.Key words: Coelaenomenodera lameensis, entomopathogenic fungi, isolate, pathogenicity, myceli

Population dynamics of the diamondback moth Plutella xylostella L. (Lepidoptera: Yponomeutidae) in the Sydney Region of Australia

The population dynamics of the diamondback moth (DBM), Plutella xylostella L. (Lepidoptera: Yponomeutidae) was investigated at three farms on the Western side of the Sydney Basin, Australia, from November 2003 to October 2004. Adult populations were monitored fortnightly by counting the number that was trapped on yellow sticky traps, which peaked around November to December (summer) in all three farms, with virtually no trap catches in the winter months (June-August). The seasonal trend of adult DBM showed a higher number per trap in summer, ranging from 34.5-41.7 compared with the other seasons. Larval and pupal densities were highest in summer (2.0-4.0 and 3.3-5.1 per plant, respectively), while the lowest numbers were recorded in winter. Rainfall had a significant impact on the DBM populations. The activity (numbers and parasitism) of the DBM parasitoid Diadegma semiclausum Héllen (Hymenoptera: Ichneumonidae) was recorded in all three farms, with the population showing a synchrony with that of the DBM. The highest number of parasitoids per trap (36.8-53.8) was recorded in summer compared with the other seasons. Parasitism was highest in the non-sprayed farm (56.3%) in summer compared with 16.4% and 31.5% in the other farms which have been sprayed with insecnticides. Canonical correspondence analysis showed environmental variables accounting for 11.2% of the variability in the insect data, out of which 83.9% was explained along the first canonical axis.© 2010 International Formulae Group. All rights reserved.Keywords: Diamondback moth, Plutella xylostella, Diadegma semiclausum, parasitism, brassic

Effects of distance from semi-natural habitat on fall armyworm (Spodoptera frugiperda, J. E. Smith) and its potential natural enemies in Ghana

Insect crop pests are a major threat to food security in sub-Saharan Africa. Configuration of semi-natural habitat within agricultural landscapes has the potential to enhance biological pest control, helping to maintain yields whilst minimising the negative effects of pesticide use. Fall armyworm (Spodoptera frugiperda, J. E. Smith) is an increasingly important pest of maize in sub-Saharan Africa, with reports of yield loss between 12 and 45%. We investigated the patterns of fall armyworm leaf damage in maize crops in Ghana, and used pitfall traps and dummy caterpillars to assess the spatial distribution of potential fall armyworm predators. Crop damage from fall armyworm at our study sites increased significantly with distance from the field edge, by up to 4% per m. We found evidence that Araneae activity, richness and diversity correspondingly decreased with distance from semi-natural habitat, although Hymenoptera richness and diversity increased. Our preliminary findings suggest that modifying field configuration to increase the proximity of maize to semi-natural habitat may reduce fall armyworm damage and increase natural enemy activity within crops. Further research is required to determine the level of fall armyworm suppression achievable through natural enemies, and how effectively this could safeguard yields