Evaluation of indigenous fungal isolates and Metarhizium anisopliae var. acriidum against adult lesser wax moth, Achroia grisella (l) (Pyralidae: Lepidoptera)

 The lesser wax moth (LWM) is a widely distributed and devastating insect pest to the honey production sector in Ethiopia. The present study aimed at investigating the potential of native fungal isolates against the lesser wax moth and assessing non target effect of one isolate of Beauveria (IITA 18) and five isolates of Metarhizium (IMI 330189, DLCO-AA83, DLCO-AA 109, DLCO-AA5, DLCO-AA14) via inoculating Ethiopian honeybee race, Apis mellifera bandasii. The effects of these six fungal isolates were evaluated in the laboratory for their pathogenicity to adult lesser wax moths. Spore dilutions were prepared in 0.5% Tween 80. Adults were treated by spraying 2 ml of conidial suspensions ranging from 2x104 to 2x107 conidia/ml. Adult lesser wax moths were found to be susceptible to all isolates and concentrations used. Comparison of post-treatment mortality of adult, lesser wax moth (LWM) at the lowest concentration (2x104 conidia/ml) revealed that infection of > 90% could be achieved by day 8 post inoculation. Investigation into effects of mycosis on percentage emergence of adults from fungal treated last instar larvae of the lwm showed no significant difference (P>0.05) between the treated and untreated controls. Laboratory based experiments on the host specificity of the six fugal isolates had no effect in which only 1 individual honeybee (0.5%) was infected with isolate IITA 18 (Beauveria spp.) while isolate DLCO-AA83 (Metarhizium spp.), caused infection in 2 individual honeybees

Studies on the pathogenicity of an oil-based formulation of metarhizium flavoviride for the desert locust, Schistocerca gregaria

SIGLEAvailable from British Library Document Supply Centre- DSC:DX180580 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Population dynamics and distribution of the coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae) on Coffea arabica L. in Southwestern Ethiopia

Population dynamics and distribution of coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae) were studied on Coffea arabica L. in southwestern region of Ethiopia. Thirty coffee trees were sampled at weekly intervals from 2000 to 2001. Findings of this study showed that coffee berry borer population had a marked seasonal variation both on dry leftover and fallen coffee berries. Number of adult borers on dry leftover berries was significantly higher than on fallen berries (&#967;2= 3.89, P < 0.05). All the developmental stages of the borer were more abundant during January to August. There were seasonal differences in the relative abundance of pre-brood, brood and post-brood female borers. Weather factors showed a marked influence on the population dynamics of the borer. Distribution of the borer covered a wide range of altitudes ranging from 1200–1770 m.a.s.l.Key words/phrases: Coffee berry borer, Coffea arabica, Ethiopia, Hypothenemus hampei, population dynamicsSINET: Ethiopian Journal of Science Vol. 27 (2) 2004: 127–13

Short Communication: Occurrence of the pea aphid, Acyrthosiphon pisum (Harris) (Homoptera: Aphididae) on wild leguminous plants in West Gojam, Ethiopia

The occurrence of pea aphid, Acyrthosiphon pisum (Harris) (Homoptera: Aphididae), on wild annual and perennial leguminous plants was studied at two locations (Adet and Wondata) in West Gojam, Ethiopia in 1999/2000 seasons. Annual and perennial leguminous wild or volunteer plants encountered in the study areas were closely monitored for the presence of pea aphid. The results showed that pea aphids infested annual legumes such as clover (Trifolium ruepellainum) (wild) and vetch (Vicia spp) carried more aphid load than clover. The aphid attacked more vetch in September and clover in October. From perennial legumes, pigeon pea (Cajanus cajan) was the most susceptible to attack by pea aphids and it was heavily infested and damaged in September and October. High plant density of vetch carried more aphid load than low plant density; sole stand of vetch plants suffered more damage than when grown mixed up with other crops or weeds suggesting the advantage of intercropping to reduce pea aphids. Key words/phrases: Acyrthosiphon pisum, Ethiopia, leguminous plants, pea aphid, wild hosts SINET: Ethiop. J. Sci Vol.26(1) 2003: 83-8

Studies on the reproductive status, catch and age compositions of the tsetse fly, Glossina pallidipes populations in the Nechisar National Park in southern Ethiopia

Studies were conducted during the dry hot period of December 1999 to April 2000 in the Nechisar National Park, Southern Ethiopia, to obtain base line data on catch, age compositions, and reproductive status of samples of Glossina pallidipes, trapped in NGU-2G traps. The objective was to assess tsetse population dynamics and to provide data on the temporal and spatial variations of the structure of the fly population at five localities (habitats). The data were to be used for the suppression phase of a Sterile Insect Technique (SIT) project in the study area. Population study in space was conducted at randomly selected five sites in and out of the park. In each vegetation type, a set of 2 NGU-2G traps baited with urine and acetone were deployed for five days during the same week of the study time. Female flies were dissected to assess ovarian age structure of populations. To determine the age of male flies wing-fray analysis was carried out using wing-fray categories (1-6). Trapped tsetse included significantly higher proportions of teneral and non-teneral females, and a lower male: female ratio. Insemination rates of the sampled flies were over 95% at all habitats. In any one habitat, the frequency of pregnancy (egg stage) predominated, followed by the first, second, and lastly, by the third instar larva. Abortion was the predominant reproductive abnormality at all habitats of the natural population of G. pallidipes. Age compositions of females (ovarian aging) showed greater proportions of females with 1–3 ovarian age categories and a physiological age between 8–40 days at all habitats. Age compositions of males (wing-fray) were significantly greater for young males (1–3 wfc) compared with old males (4–6 wfc). The studies of this base line data collection with other operational studies will be a prerequisite to assess the feasibility of the proposed area wide eradication project and to develop appropriate strategies to suppress and finally to eradicate the fly by situational releases of sterilized male flies.Key words/phrases: Abortion, age reproductive status, Glossina pallidipes, NGU-2G traps, pregnancy SINET: Ethiopian Journal of Science Vol. 28 (1) 2005: 51-6

Field Attractants for Pachnoda interrupta Selected by Means of GC-EAD and Single Sensillum Screening

The sorghum chafer, Pachnoda interrupta Olivier (Coleoptera: Scarabaeidae: Cetoniinae), is a key pest on sorghum, Sorghum bicolor (L.) Moench (Poaceae), in Ethiopia. At present there is a lack of efficient control methods. Trapping shows promise for reduction of the pest population, but would benefit from the development of attractive lures. To find attractants that could be used for control of P. interrupta, either by mass trapping or by monitoring as part of integrated pest management, we screened headspace collections of sorghum and the highly attractive weed Abutilon figarianum Webb (Malvaceae) for antennal activity using gas chromatograph-coupled electroantennographic detection (GC-EAD). Compounds active in GC-EAD were identified by combined gas chromatography and mass spectrometry (GC-MS). Field trapping suggested that attraction is governed by a few influential compounds, rather than specific odor blends. Synthetic sorghum and abutilon odor blends were attractive, but neither blend outperformed the previously tested attractants eugenol and methyl salicylate, of which the latter also was part of the abutilon blend. The strong influence of single compounds led us to search for novel attractive compounds, and to investigate the role of individual olfactory receptor neurons (ORNs) in the perception of kairomones. We screened the response characteristics of ORNs to 82 putative kairomones in single sensillum recordings (SSR), and found a number of key ligand candidates for specific classes of ORNs. Out of these key ligand candidates, six previously untested compounds were selected for field trapping trials: anethole, benzaldehyde, racemic 2,3-butanediol, isoamyl alcohol, methyl benzoate and methyl octanoate. The compounds were selected on the basis that they activated different classes of ORNs, thus allowing us to test potential kairomones that activate large non-overlapping populations of the peripheral olfactory system, while avoiding redundant multiple activations of the same ORN type. Field trapping results revealed that racemic 2,3-butanediol is a powerful novel attractant for P. interrupta

The synergistic effects of Metarhizium anisopliae (Metschikoff) with the acyl urea insecticides teflubenzuron and diflubenzuron for Schistocerca gregaria (Orthoptera: Acrididae)

The acyl urea insecticide teflubenzuron (=Nomolt -) caused loss of appetite, ecdysial failure and eventual death in 4th instar Schistocerca gregaria. The entomopathogenic fungus Metarhizium anisopliae also caused mortality due to mycosis among nymphs of the locust. Enhanced mortality occurred following dual application of the growth regulator and the fungus, which at one combination was synergistic. In another experiment, the fungus was exposed to cuticle treated with acetone (the carrier for the insecticide). This reduced the effectiveness of the fungus. An ultrastructural study showed the effect of the joint application of another acyl urea diflubenzuron (= Dimlin-) and Metarhizium anisopliae on locust cuticle. Disruption of the lamellae pattern was observed in some areas of cuticle. This is consistent with localised disruption of chitin synthesized during treatment with Dimlin. This compound, that has a short half-life in the locust, was applied to the food at 5 day interval over a 15 day period. Clearing zones in the cuticle around penetrant hyphae suggested action of cuticle degrading fungal enzymes. These zones were more extensive around gyphae in Dimlin-affected cuticle suggesting possible enhanced hydrolysis of cuticle protein by fungal proteases in the absence of chitin. SINET: Ethiopian Journal of Science Vol. 24, No. 1 (June 2001), pp. 113-125 Key words/phrases: Diflubenzuron, Metarhizium anisopliae, Schistocerca gregaria, teflubenzuro

Effective utilization period of long-lasting insecticide treated nets against Malaria vector mosquitoes and the species composition in North West Ethiopia

The study was conducted to evaluate the bioefficacy of long-lasting insecticide treated nets (LLITNs) (PermaNet®2.0) over time and the species composition of Anopheles mosquitoes around Bahir Dar. The space spray collection method was used to determine the species composition of indoor resting Anopheles mosquitoes in the study area. Field collected samples of household used PermaNet® 2.0 were tested for their bioefficacy against laboratory reared An. arabiensis following the World Health Organisation standard cone test protocol. The study revealed that 75% of Anopheles mosquitoes collected from indoor location in the study area was An. arabiensis indicating that this species was the primary potential vector of malaria in the study area. The mean percentage knockdown effect of PermaNet® 2.0 up to two years of household usage against females An. arabiensis was 100%. However, this effect decreased to 44.5% after three and half years of household use. There was no significant difference (P &gt; 0.5) in the mean percent mortality caused by PermaNet® 2.0 after six months and two years household usage (92.5% and 84%, respectively). However, under laboratory conditions there was recorded a markedly significant reduction (P &lt; 0.01) in the mean percent mortality of females An. arabiensis exposed to PermaNet® 2.0 that has been used for three and half years (27%). Close monitoring on the feeding and resting behavior of malaria vector mosquitoes and awareness creation on the proper utilization of the bed net need to be conducted to check and maintain its feasibility as part of integrated malaria vector management. Keywords/phrases: Anopheles arabiensis, Bioefficacy, Long-lasting insecticide treated nets, PermaNetEthiop. J. Biol. Sci., 10(1): 103-110, 201