Browsing by Author "Wilson, D.D."
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Item Agronomic Performance and Susceptibility of Seven Ghanaian Improved Sweet Potato Varieties to the Sweet Potato Weevil, Cylas spp. (Coleoptera: Brentidae) in Coastal Savanna Zone of Ghana(African Entomology, 2019-10-04) Adom, M.; Fening, K.O.; Wilson, D.D.; Adofo, K.; Bruce, A.Y.Sweet potato (Ipomoea batatas (L.) Lam. is an important food crop adaptable to a broad range of agro-ecological conditions. The knowledge of the performance of the available varieties under a specific ecological condition is important to improve the production. A field experiment was carried out at the University of Ghana farm during the major and minor rainy seasons of 2015 to determine the yield performance of seven improved Ghanaian sweet potato varieties (CRI-Apomuden, CRI-Ligri, Faara, CRI-Bohye, CRI-Dadanyuie, Okumkom, Sauti) and their susceptibility to the sweet potato weevil, Cylas spp. (Coleoptera: Brentidae). Significant difference was found in the storage root yield among the varieties, with CRI-Ligri having the highest in both major (23.11 t/ha) and minor (22.49 t/ha) rainy seasons. CRI-Apomuden and CRI-Ligri scored the highest levels of infestation by sweet potato weevil in the major and minor seasons (1.94 and 2.00, 1.84 and 1.96, respectively) and yield loss (44.44 % and 42.80 %, 23.84 % and 23.87 %, respectively). While the lowest infestation levels in the major rainy season were recorded on Faara and Okumkom (1.18 and 1.31, respectively) with yield losses of 10.32 % and 9.09 %, respectively. However, in the minor rainy season, there was no significant difference among Faraa, Okumkom, CRI-Bohye and CRI-Dadanyuie in terms of infestation level and yield losses. Significant difference was found in all measured root characteristics including the shortest weevil distance, root neck length, root length, root girth and root size index. The storage root infestation had a strong negative correlation with the shortest weevil distance, a strong positive correlation with the root size index and a weak negative correlation with root neck length. In this study, Okumkom appeared to be less susceptible to sweet potato weevil infestation with relatively acceptable yield performance and therefore can be recommended for use by farmers to improve sweet potato production.Item Behavioral Repertory of Adult Cylas formicarius (Fabricius) (Coleoptera: Brentidae)(Coleopterists Bulletin, 2018-03) Starr, C.K.; Wilson, D.D.; Kays, S.J.Adult female and male sweetpotato weevils, Cylas formicarius (Fabricius), have repertories of at least 19 and 21 behavior patterns, respectively. These are described and named, including eight self-grooming patterns. Consistent with the species' slight sexual dimorphism, few behavior patterns are peculiar to one sex. The sequence of self-grooming movements is analyzed for each sex. Comparative assays of vagility and overall activity do not show any difference between the sexes.Item Bionomics of the sweet potato weevil, Cylas puncticollis (Coleoptera: Brentidae) on four different sweet potato varieties in sub-Saharan Africa(Journal of Agriculture and Rural Development in the Tropics and Subtropics, 2018) Adom, M.; Wilson, D.D.; Fening, K.O.; Bruce, A.Y.; Adofo, K.Sweet potato (Ipomoea batatas (L.) Lam.) is an important staple food crop in sub-Saharan Africa. A limiting production factor is infestation by the sweet potato weevil Cylas puncticollis (Boheman) (Coleoptera: Brentidae). The use of host plant resistance is an essential component of Integrated Pest Management (IPM). Therefore, the bionomic parameters of C. puncticollis were studied under laboratory conditions (30 ± 1 °C and 75 ± 5 % RH) on four sweet potato varieties commonly grown in Ghana (Apumoden, Ligri, Bohye, and Okumkom) to determine their susceptibility to the pest. There were significant varietal differences between some of the parameters. Egg to adult development time was highest on Okumkom while larval survival, emergence rate, intrinsic rate of increase, and the net reproductive rate were lowest on Bohye. The results of this study indicate that Bohye was the least susceptible variety compared to the other varieties tested and can be used in host plant resistance as part of an IPM programme against C. puncticollis in Ghana.Item Cross mating studies among five fruit fly parasitoid populations: Potential biological control implications for tephritid pests(BioControl, 2008-10) Billah, M.K.; Kimani-Njogu, S.W.; Wharton, R.A.; Overholt, W.A.; Wilson, D.D.; Cobblah, M.A.The reproductive compatibility between four different species/populations of the tephritid parasitoid Psyttalia (Walker) species from Kenya and individuals of the morphologically identical Psyttalia concolor (Szépligeti) (Hymenoptera: Braconidae) from a laboratory culture in Italy used in augmentative biological control of olive fly, Bactrocera oleae (Gmelin) (Diptera: Tephritidae) was assessed through cross mating tests using single-pair and group mating methods. Reciprocal crosses among the species resulted in the production of viable offsprings up to the second generation. In spite of the successful production of viable offspring in the laboratory, Psyttalia species are known to have specific host fruit and/or host fly preferences and populations/species may be isolated in one way or the other. However, it is not known whether these populations/species interbreed in the field. We discuss the ability of these parasitoids to interbreed and the potential effects of that on their use as biological control agents, especially in environments where other closely related species are present or in situations where multiple parasitoid introductions are intended. © 2007 International Organization for Biological Control (IOBC).Item Cross mating studies of Psyttalia species (Hymenoptera: Braconidae): Potential implications for biological control of tephritid pests(BioControl 53 (5): 709-724, 2008) Billah, M.K.; Kimani-Njogu, S.W.; Overholt, W.A.; Wharton, R. A.; Wilson, D.D.; Cobblah, M.A.The reproductive compatibility between four different species/populations of the tephritid parasitoid Psyttalia (Walker) species from Kenya and individuals of the morphologically identical Psyttalia concolor (Szépligeti) (Hymenoptera: Braconidae) from a laboratory culture in Italy used in augmentative biological control of olive fly, Bactrocera oleae (Gmelin) (Diptera: Tephritidae) was assessed through cross mating tests using single-pair and group mating methods. Reciprocal crosses among the species resulted in the production of viable offsprings up to the second generation. In spite of the successful production of viable offspring in the laboratory, Psyttalia species are known to have specific host fruit and/or host fly preferences and populations/species may be isolated in one way or the other. However, it is not known whether these populations/species interbreed in the field. We discuss the ability of these parasitoids to interbreed and the potential effects of that on their use as biological control agents, especially in environments where other closely related species are present or in situations where multiple parasitoid introductions are intended.Item The Distribution and Abundance of the Stem-Galling Fly, Cecidochares connexa (Macquart) (Diptera: Tephritidae), a Biological Control Agent of Chromolaena odorata (L.) (Asteraceae), in Ghana(African Entomology, 2018-10) Aigbedion-Atalor, P.O.; Wilson, D.D.; Eziah, V.Y.; Day, M.D.; Paterson, I.D.Chromolaena odorata (L.) R.M. King and H. Robinson (Asteraceae: Eupatorieae) is one of the worst invasive weeds in West Africa, and a serious biotic threat to food security. The stem-galling fly, Cecidochares connexa (Macquart) (Diptera: Tephritidae), a biological control agent for C. odorata, was released in the Ivory Coast in 2003 and first detected in Ghana in 2014. The spatiotemporal distribution and abundance of C. connexa in Ghana was determined by country-wide surveys from 2015 to 2016. Galls were found in varying densities across Ghana but gall densities were consistently low east of Lake Volta. A limited survey conducted in the extreme west of Togo in 2016, found the gall fly also in low numbers. There was a significant correlation between C. connexa gall densities and the distance from the release sites in the Ivory Coast. The distribution and abundance of the gall fly in Ghana could be explained by its spread from the original release sites over time and/or the much drier conditions east of Lake Volta. Cecidochares connexa has dispersed a distance of about 1000 km over a 10-year period and, while there is some evidence that the gall fly is still dispersing towards the east, its range and population size could be limited by the dry climatic conditions in the east of Ghana and in Togo. Actively redistributing the agent over this dry corridor to the more humid and higher rainfall areas of Nigeria, may result in the spread of this agent through the rest of West and Central Africa, thereby aiding the control of C. odorata in the region.Item The effect of host larvae on three Psyttalia species (Hymenoptera: Braconidae), parasitoids of fruit-infesting flies (Diptera: Tephritidae)(International Journal of Tropical Insect Science, 2005-09) Billah, M.K.; Kimani-Njogu, S.; Overholt, W.A.; Wharton, R.A.; Wilson, D.D.; Cobblah, M.A.Three species of fruit fly parasitoids, Psyttalia concolor (Szépligeti), Psyttalia cosyrae (Wilkinson) and Psyttalia lounsburyi (Silvestri) (Hymenoptera: Braconidae) were reared on different host larvae to determine the effects of host species, size and colour on parasitoid development. Ovipositor, ovipositor sheath and hind tibia lengths were found to be different for progenies from preferred and non-preferred host larvae. Ratios of ovipositor-tibia and ovipositor sheath-tibia showed no difference when P. concolor was reared on a bigger host (Ceratitis cosyra (Walker) (Diptera: Tephritidae), whereas rearing P. cosyrae on a smaller host (C. capitata (Wiedemann) showed significant differences. Comparison of the linear measurements, ratios and number of flagellomeres of parasitoids reared on preferred hosts, separated the species into their natural groupings. When reared on a different-coloured host, P. lounsburyi lost its dark markings but other characters remained unchanged. Morphometric analysis also indicated differences between parasitoids reared on preferred host larvae and those reared on non-preferred host larvae. Rearing parasitoids on larvae other than their preferred hosts resulted in colour and size changes, and thus, these characters alone were not reliable for the identification of parasitoids. This is especially important in post-release sampling surveys to ascertain establishment of the parasitoids in new environments where they may adapt to new host species. © ICIPE 2005.Item Effects of irradiation on physical and sensory characteristics of cowpea seed cultivars (Vigna unguiculata L. Walp)(Radiation Physics and Chemistry, 2012-01) Ocloo, F.C.K.; Darfour, B.; Ofosu, D.O.; Wilson, D.D.Cowpeas (Vigna unguiculata L. Walp) are leguminous seeds widely produced and consumed in most developing countries of sub-Saharan Africa where they are a good source of affordable proteins, minerals and vitamins to the mainly carbohydrate-based diet of sub-Saharan Africa. At storage cowpea may be attacked by insects that cause severe damage to the seeds. The objective of this study was to investigate the effects of gamma irradiation on some physical and sensory characteristics of cowpea seed cultivars. Four cowpea cultivars were irradiated with gamma radiation at dose levels of 0.25, 0.50, 0.75, 1.0 and 1.5 kGy. Moisture content, thousand grain weight and bulk densities were determined as well as the amount of water absorbed during soaking and some sensory characteristics were equally determined. All the physical parameters studied were not significantly (p>0.05) affected by the radiation. There was no significant (p>0.05) effect of the radiation on the sensory attributes like flavour, taste, texture, softness and colour of the cowpea seeds. Similarly, the radiation did not affect significantly (p>0.05) the acceptability of the treated cowpea cultivars. © 2011 Elsevier Ltd.Item Eight decades of invasion by Chromolaena odorata (Asteraceae) and its biological control in West Africa: the story so far(Biocontrol Science and Technology, 2019-09-24) Adom, M.; Aigbedion-Atalor, P.O.; Day, M.D.; Uyi, O.; Egbon, I.N.; Idemudia, I.; Igbinosa, I.B.; Paterson, I.D.; Braimah, H.; Wilson, D.D.; Zachariades, C.Chromolaena odorata (L.) R.M. King and H. Robinson (Asteraceae) is a perennial weedy shrub of neotropical origin and a serious biotic threat in its invasive range. The Asian-West Africa (AWA) biotype of C. odorata present in West Africa is both morphologically and genetically different from the southern African (SA) biotype. The AWA biotype was first introduced into Nigeria in the late 1930s and rapidly spread across West Africa. Currently, 12 of the 16 countries in West Africa have been invaded, with significant negative effects on indigenous flora and fauna. However, locals in West Africa have found several uses for the weed. As chemical, physical and other conventional methods were unsustainable, costly and largely ineffective, three biological control agents, Apion brunneonigrum (Coleoptera: Brentidae), Pareuchaetes pseudoinsulata (Lepidoptera: Erebidae) and Cecidochares connexa (Diptera: Tephritidae), have been released in West Africa between the 1970s and the early 2000s. However, only C. connexa and P. pseudoinsulata established, contributing to the control of the weed, in six and four countries in West Africa respectively. Limited research funding, the absence of post-release evaluations of the established agents, and the ‘conflict of interest’ status of C. odorata (i.e. being beneficial for local use but damaging to ecosystem services and agriculture), are serious factors deterring the overall biological control effort. Here, using historical records and field surveys, we examine the invasion history, spread, impacts, and management of C. odorata in West Africa and make recommendations for the sustainable management of C. odorata in the region.Item An Environmentally-Friendly and Participatory Approach to the Management of an Invasive Aquatic Weed(University of Ghana, 2010-06) Awuni, S.; Wilson, D.D.; DeGraft-Johnson, K.A.A.; Akpabey, F.J.K.; University of Ghana, College of Basic and Applied Sciences, Institute for Environment and Sanitation StudiesBiological control of water fern, Salvinia molesta was studied in concrete tanks of area 4 m2 each at the insectary of the Department of Animal Biology and Conservation Science (DABCS), University of Ghana, Legon and Jewi Wharf in the Western Region. The impact of Cyrtobagous salviniae on S. molesta was studied in Legon and Jewi Wharf. Results show that there was damage inflicted on S. molesta by the C. salviniae which manifested with increase in percentage and area damage of S. molesta with time in both locations (correlation coefficient = 0.99 in both cases). The damage became evident when leaves turned brown due to infestation, with the leaves being more likely to fall off during handling The rate of multiplication of C. salviniae was also studied through the numbers recovered per quadrat Population estimation using a 0.25 m * 0.25 m quadrat during sampling yielded up to 525 adult weevils in the tank at Legon in two months, giving a 6.4 fold increase in population and a density of 131 adult weevils per square metre, that of Jewi Wharf yielded 608 adult weevils in the tank by the third month giving a 16.4 fold increase in population and a density of 152 adult weevils per square metre. The results indicated that C. salviniae was able to survive and reproduce on S. molesta. The results also indicated that S. molesta reduced in area coverage due to damage and the population of C. salviniae also reduced in a predator-prey relationship pattern. Assessment of biological control potential of a closely related species, Salvinia nymphellula in a large plastic pool at DABCS and on the lower Volta (Big Ada) in the Greater Accra Region was also carried out. The impact of C. salviniae released was monitored over a five month period in Legon and in the lower Volta. Sampling was done to determine the percentage damage of S. nymphellula by C. salviniae. The results indicated that C. salviniae could not survive and reproduce on S. nymphellula. As a result, there was no damage characterized by C. salviniae. The results confirm the fact that C. salviniae is host-specific to S. molesta and will not even feed on a closely related species, 5. nymphellula. The results of the community perceptions on invasive weeds and their control indicated that the communities prefer manual control of weeds to any other method. The Jewi Wharf community was aware of biological control of weeds but not that of the lower Volta. Jewi Wharf community however had mixed perceptions of biological control and did not prefer the method. It was again indicated that perceptions on the invasive water weeds were based on the socioeconomic effects which they encounter from the spread of the weeds, as it has always been the case in other parts of the world where the weeds are prevalent.Item Evaluation of the efficacy of a commercial formulation of beauveria bassiana for the control of the invasive fruit fly bactrocera dorsalis (Diptera: Tephritidae)(Koul Research Foundation, 2016) Marri, D.; Gomez, D.A.M.A.; Wilson, D.D.; Billah, M.; Yeboah, S.; Osae, M.Evaluation of the efficacy of a commercial formulation of Beauveria bassiana (Botanigard® ES) for the control of the oriental fruit fly, Bactrocera dorsalis (Diptera: Tephritidae) was carried out on three developmental stages. Botanigard® ES containing 11.3% Beauveria bassiana GHA strain was applied to larvae, pupae and adults at concentrations of 106, 53.0, 26.5, 13.3 and 6.65 (× 106 spores/mL). The effect of B. bassiana on B. dorsalis was dose dependent, increasing with fungal spore concentration. The results showed that an optimum dose of 26.5 × 106 spores/mL killed 50% of adult flies within 4-5 days and 99% within 8-9 days. The same dose reduced adult emergence from infected pupae from 97% in the control to 46% in the treated groups. Fungal treatment at 26.5 × 106 spores/mL also killed almost all adults emerging from pupae and adults treated directly. Comparing methods of fungal application in the field, the result indicated that applying the fungus in fruit fly traps in mango canopies is a better method for fruit fly control in the field as compared to soil surface spray method. However, both methods could be used simultaneously for better results. © 2016 (KRF).Item Marching across and beyond West Africa: First record of the stem-galling fly Cecidochares connexa (Diptera: Tephritidae) in Central Africa and the implications for biological control of Chromolaena odorata (Asteraceae)(PLOS, 2021) Aigbedion-Atalor, P.O.; Idemudia, I.; Adom, M.; Forchibe, E.E.; Tossou, H.; Wilson, D.D.; Day, M.D.The Neotropical invasive plant Chromolaena odorata R.M. King and H. Robinson (Astera ceae) is a serious weed in West and Central Africa and two biological control agents that have been introduced into West Africa to help reduce its impacts on agriculture and biodiver sity, have established. The stem-galling fly, Cecidochares connexa (Macquart) (Diptera: Tephritidae), has spread widely across West Africa since its release in only Coˆte d’Ivoire, occurring in six countries. This study aimed to investigate whether the gall fly had spread fur ther across West Africa and into Central Africa. Here, we surveyed C. odorata for C. con nexa galls in Cameroon between October 2018 and October 2020, along roadsides, on farms, residential areas, and abandoned plots, encompassing various vegetation types. Additional surveys were conducted across four countries (Ghana, Togo, Benin Republic and Nigeria) in West Africa that we considered the probable pathway for the spread of the gall fly into Central Africa. Cecidochares connexa was present at five of the six locations sur veyed in Cameroon, albeit in varying abundance. In Africa, these findings represent the first ever report of C. connexa outside of West Africa. In West Africa, we recorded significant expansion in the geographic range of C. connexa, as reflected in the absent-present record of C. connexa in two locations in Nigeria and one in Ghana, as well as its occurrence in all locations surveyed in Benin Republic and Togo. Clearly, Ghana, Togo, Benin Republic and Nigeria served as the dispersal pathway of C. connexa from the release sites in Coˆte d’Ivoire into Cameroon, covering over 2,300 km. Following the spread and establishment of C. con nexa into Cameroon, we anticipate that it will continue to spread further into other parts of Central Africa which are climatically suitable. Cecidochares connexa is currently the only biological control agent for C. odorata in Central Africa. Given that it has significantly reduced populations of C. odorata in other countries where it has established, it is expected to have a similar impact in Central Africa.Item Morphometric Studies of the Sweet Potato Weevil, Cylas Species- Complex in Southern Ghana(Science and Development (A Journal of the College of Basic and Applied Sciences (CBAS), University of Ghana), 2017-12) Billah, M.K.; Agbessenou, A.; Wilson, D.D.; Dekoninck, W.; Vangestel, C.The Sweet potato weevil, Cylas species, is a key pest of sweet potato, and widely distributed on the African continent. The management of the pest is limited because its taxonomic status is not clear. Populations of the same species occupying distinct localities experience different ecological and climatic pressures that might result in differentiation in traits. This study sought to identify and compare body sizes of Cylas species from four regions in southern Ghana – Central, Eastern, Greater Accra and Volta. Of the 6,686 samples collected from the four regions, two species were identified: Cylas brunneus Fabricius, and Cylas puncticollis Boheman. Twelve morphometric characters were examined and measured, of which four traits - elytra and rostrum lengths, pronotum and head widths contributed most to the variations observed. In C. puncticollis, individuals with the longest body were recorded in Greater Accra Region (7.084 ± 0.089 mm), while those in the Central Region had the smallest body size (6.786 ± 0.086 mm). Our findings suggest that distinct localities may influence changes in body size.Item Physical, proximate, functional and pasting properties of flour produced from gamma irradiated cowpea (Vigna unguiculata, L. Walp)(Radiation Physics and Chemistry, 2012-04) Darfour, B.; Wilson, D.D.; Ofosu, D.O.; Ocloo, F.C.K.Cowpeas are leguminous seeds widely produced and consumed in most developing countries of sub Saharan Africa. The aim of this study was to determine the physical, proximate, functional and pasting properties of flour obtained from gamma irradiated cowpea. Four cowpea cultivars were irradiated with gamma radiation at dose levels of 0.25, 0.5, 0.75, 1.0 and 1.5. kGy with the unirradiated cultivars serving as controls. The samples were hammer milled, sieved and stored at 4. °C for analysis. Physical, proximate, functional, pasting properties were determined using appropriate methods. In general, the irradiation dose applied to cowpea for insect control did not significantly affect the physical and proximate properties of the flour. However, significant increase (p<0.05) was achieved in paste bulk density, water and oil absorption capacities, foam capacities and least gelation concentrations of flour in general, which may be attributed to the irradiation. The radiation reduced the swelling power and water solubility index significantly. The peak temperature, peak viscosity and setback viscosity of the pastes were significantly (p<0.05) reduced while breakdown viscosity was significantly (p<0.05) increased by the radiation. It was established that the doses used on cowpea affected both the functional and pasting properties of the flour. © 2011 Elsevier Ltd.Item Resting Behaviour of Endophilic Anopheline Vectors in Three Ecological Zones of Southern Ghana and its Implications for the use of Entomopathogenic Fungi(University of Ghana, 2014-09) Osae, M.Y.; Wilson, D.D.; Wilson, M.D.; Koekemoer, L.L.; University of Ghana, College of Basic and Applied Sciences Department of Nuclear Agriculture and Radiation ProcessingThe aim of this study was to determine the resting behaviour and factors that influence the choice of resting sites by endophilic anopheline mosquitoes in southern Ghana. The study was carried out in six villages across three ecological zones of southern Ghana, including: the forest ecological zone (FEZ), the coastal savannah ecological zone (CSEZ) and the forest-transition ecological zone (FTEZ). For every mosquito collected, the indoor resting sites was characterised and microclimate at the actual resting site recorded using a data logger. In the laboratory, full diagnostics was carried out on a sub-sample. Resting devices constructed from different materials were tested in a screen house and in village rooms. The dominant anopheline vectors include Anopheles gambiae s.s., An. coluzzii and An. funestus. An gambiae s.s. was the most dominant species in the villages from the FEZ and FTEZ, whereas An. coluzzii was most dominant in the CSEZ. An. funestus was present in the FEZ and CSEZ but almost absent from the FTEZ. The two kdr mutations (L1014F and L1014S) were present in all the ecological zones and in both An. gambiae s.s. and An. coluzzii. This is the first report of the L1014S mutation from Ghana. The populations were highly anthropophagic and Plasmodium falciparum was present in populations from all the villages studied. Woody materials appeared to be the most preferred resting materials for An. gambiae, accounting for 47 % of all the resting sites for that species. They were also found on fabrics (26 %), wall materials (12 %), and roof materials (10 %). Similarly, An. funestus preferred to rest on woody materials (58 %), followed by wall materials (21 %), fabrics (11 %) and roofing materials (7 %). For An. coluzzii, fabrics were the most preferred resting materials (38 %) followed by roof materials (21 %), wooden materials (19 %) and wall materials (9 %). All the three vector species preferred to rest higher up the room and closer to the walls, with large proportions of An. gambiae s.s. (75.94 %), An. funestus (73.60 %) and An. coluzzii (58.19 %) found resting at heights above 200 cm from the floor. With reference to the nearest wall, high proportions of An. gambiae s.s. (68.38 %), An. coluzzii (80.98 %) and An. funestus (68.29 %) were collected within 50 cm from the closest wall. Although microclimatic conditions varied widely in the indoor environment and even at the specific resting sites, higher proportions of the endophilic anophelines were collected within narrow ranges of temperature (27-30 oC), relative humidity (65-75 %) and light intensity (0-20 Lux). Black felt and black cotton cloth were the most preferred resting devices for blood-fed females in both screen house trials and field. In general, the presence of the three most efficient vectors of malaria from indoor collections in southern Ghana and the fact that they were highly anthropophagic and effectively transmitting malaria is a high call for intensifying vector control efforts. Knowledge of the indoor resting behaviour of the major endophilic Anopheles vectors of southern Ghana paves the way for developing fungal spore deployment strategies for field implementation. This study has established that all the three endophilic Anopheles species in southern Ghana rest higher up in village rooms, prefer to rest on darker coloured materials in cool humid areas. It has further demonstrated that black felt and black cotton cloth are attractive to blood-fed females seeking resting sites to digest blood meal and develop their eggs. Guided by this knowledge, future research should focus on designing these preferred materials into resting devices that create suitable microhabitats to which endophilic anopheline mosquitoes can be attracted and contaminated with fungal spores. Further research is also needed to determine the efficacy and persistence of fungal spores on these preferred resting materials so as to determine application rates and frequency.Item Species Composition, Biology and Management of Sweet Potato Weevils (Cylas Species) In Southern Ghana.(University of Ghana, 2000-09) Darko, S.Y.; Cobblah, M.A.; Wilson, D.D.; University of Ghana, College of Basic and Applied Sciences, School of Agriculture, Department of Crop ScienceSpecies composition of sweet potato weevils (Cylas spp) on two sweet potato varieties was determined in the southern parts of the country. One species, Cylas puncticollis Boh. was found to be present in the southern part of Ghana. Studies on the biology of Cylas puncticollis were evaluated on two varieties, red and white varieties, under laboratory conditions at 27.0°C and 70% RH The incubation period of the eggs were 4 days on the red variety and 5 days on the white variety. Larval stages ranged from 10-11 days on the red and 10-12 days on the white. The pupal stage lasted 6-8 days on the red and 7-8 days on the white. Three larval instars were identified. Total developmental period from the egg stage to the adult stage ranged from 19-23 days on the red variety and 19-25 days on the white variety. Limited copulation significantly (P<0.05, t-test) increased oviposition and longevity periods of female weevils on both varieties. However, there was no significant difference in the number of eggs laid by females with limited copulation and those with unlimited copulation. Average percentage hatchability of eggs laid by females with limited copulation was 79.5 % and that of females with unlimited copulation was 85.7%. Cores from sweet potato [Ipomoea batatas (L.) Lam] root tubers (red and white varieties) were presented to Cylas puncticollis in choice- and no- choice bioassays. The red variety was significantly (P<0.05) preferred for oviposition in the choice bioassay. The effect of treatments (fertilizer, furadan, a combination of fertilizer and furadan) on sweet potato weevil populations was evaluated on two varieties in two separate fields. In both fields analysis showed that there was no significant difference (P>0.05, AOV) between the treatments on the weevils’ population. Treatment effect on weevils’ infestation (damage) of tubers on the two varieties was assessed during harvesting. The effects of the treatments did not differ significantly (P>0.05) from each other and from the control. However, furadan moderately reduced tuber infestation (damage) during the two planting seasons.Item With or without you: stem-galling of a tephritid fly reduces the vegetative and reproductive performance of the invasive plant Chromolaena odorata (Asteraceae) both alone and in combination with another agent(BioControl, 2019-02) igbedion-Atalor, P.O.; Day, M.D.; Idemudia, I.; Wilson, D.D.; Paterson, I.D.With or without another biological control agent, the specialist folivore Pareuchaetes pseudoinsulata, the stem-galling fly Cecidochares connexa reduced the performance of the invasive alien plant, Chromolaena odorata in Ghana. There was a strong significant negative relationship between gall densities of the gall fly and stem height, and the number of stems and flower heads of C. odorata. Pareuchaetes pseudoinsulata had very little impact on any C. odorata parameters. However, at sites where both C. connexa and P. pseudoinsulata occurred simultaneously, the performance of C. odorata was significantly reduced when compared with control plants. Increasing densities of both agents had a strong significant negative correlative effect on C. odorata plant parameters. Cecidochares connexa was recorded in all five regions of the country sampled, while P. pseudoinsulata was recorded in four regions. Densities of both agents declined in the dry season, but galls were persistent throughout the study period. This is the first report of the impact of C. connexa on C. odorata in the West African sub-region since its introduction to Cote d’Ivoire in 2003 and it is clear that the agent has a significant impact on C. odorata in Ghana. Further surveys are required to determine the impact of both biological control agents in other parts of the sub-region where they have established. © 2018, International Organization for Biological Control (IOBC).