Environmental & Physical Sciences

Research Papers/Topics in Environmental & Physical Sciences

Distribution of Candidatus Liberibacter species in eastern Africa, and the first Report of Candidatus Liberibacter asiaticus in Kenya

Abstract: Huanglongbing (HLB) is a serious disease of Citrus sp. worldwide. in Africa and the Mascarene islands, a similar disease is known as African citrus greening (AcG) and is associated with the bacterium Candidatus Liberibacter africanus (Laf). in recent years, Candidatus Liberibacter asiaticus (Las) associated with the severe HLB has been reported in ethiopia. thus, we aimed to identify the Liberibacter species affecting citrus, the associated vectors in Eastern Africa and their ecolo...

Stable flies, Stomoxys calcitrans L. (Diptera: Muscidae), improve offspring fitness by avoiding oviposition substrates with competitors or parasites.

Abstract: Oviposition site selection by gravid female insects is an important determinant inspecies distribution, abundance, and population dynamics. Females may assess thesuitability of a potential oviposition substrate by using cues from conspecific orheterospecific individuals already present. Here, we assessed whether the presenceof conspecific or heterospecific larvae and parasites influenced oviposition decisionsby the stable fly,Stomoxys calcitrans(Linneaus). Using dual and multiple-c...

Exploring Black Soldier Fly Frass asNovel Fertilizer for Improved Growth,Yield, and Nitrogen Use Efficiency ofMaize Under Field Conditions

Abstract: Black soldierfly frass fertilizer (BSFFF) is increasingly gaining momentum worldwide asorganic fertilizer. However, research on its performance on crop production remains largelyunknown. Here, we evaluate the comparative performance of BSFFF and commercialorganic fertilizer (SAFI) on maize (H513) production. Both fertilizers were applied at the ratesof 0, 2.5, 5, and 7.5 t ha-1, and 0, 30, 60, and 100 kg nitrogen (N) ha-1. Mineral fertilizer (urea)was also applied at 0, 30, 60 and ...

Entomopathogenic fungi as endophytes for biological control of subterranean termite pests attacking cocoa seedlings.

Abstract: Abstract:This study was conducted in the scope of developing a sustainable effective approach againstsubterranean termite pests using entomopathogenic and endophytic fungus-based biopesticides.Termites,Odontotermesspp. workers, were tested for their susceptibility to 15 entomopathogenicfungal isolates through the direct spraying of conidia suspensions at 1×108conidia/mL. In general,all the isolates screened were pathogenic, with 100% mortality 4–7 days post-inoculation. However,...

Assortments of digestive enzymes induced in first instar larvae of Busseola fusca feeding on different plants

Abstract: The stem borer Busseola fusca (Fuller) (Lepidoptera: Noctuidae) is an important pest of maize and sorghum in sub-Saharan Africa. This insect has oligophagous feeding habits, feeding mostly on maize and sorghum with a narrow range of wild Poaceous plant species. We hypothesised that first instar B. fusca larvae, the critical stage for successful establishment on a host plant, can establish and then grow on a particular plant as a result of induction of a complement of digestive enzy...

Experimental feeding studies with crickets and locusts on the use of feed mixtures composed of storable feed materials commonly used in livestock production.

Abstract: Insects such as the Mediterranean field cricket, Gryllus bimaculatus and the Desert locust, Schistocerca gregaria, are emerging as potential sources of human food and feed for livestock. High nutritive value and efficient feed conversion make them attractive for commercial production as novel livestock, but these properties strongly vary with the insects´ diet. Current mass-rearing protocols are based on fresh, non-storable feed materials. This requires constant supply and makes t...

Characterization of Male-Produced Aggregation Pheromone of the Bean Flower Thrips Megalurothrips sjostedti (Thysanoptera: Thripidae)

Abstract: Aggregation of the bean flower thrips, Megalurothrips sjostedti (Trybom) (Thysanoptera: Thripidae), has been observed on cowpea, Vigna unguiculata (L.) Walp. To understand the mechanism underpinning this behavior, we studied the responses of M. sjostedti to headspace volatiles from conspecifics in a four-arm olfactometer. Both male and female M. sjostedti were attracted to male, but not to female odor. Gas chromatography/mass spectrometry (GC/MS) analyses revealed the presence of t...

Spread and impact of fall armyworm (Spodoptera frugiperda J.E. Smith) in maize production areas of Kenya

Abstract: Fall armyworm (FAW), one of the most important pests of maize in Latin America, suddenly appeared in Africa in 2016 and spread rapidly. Estimates of crop losses due to FAW are essential in order to compare the impact of these losses with the cost of controlling FAW and advise appropriate technology dissemination and policy. In this study, therefore, crop losses due to FAW in 2017 and 2018 were estimated in all the maize production areas of Kenya. Data were collected during June and...

Unexpected diversity of Wolbachia associated with Bactrocera dorsalis (Diptera: Tephritidae) in Africa.

Abstract: Bactrocera dorsalis (Hendel) is an important pest of fruit-bearing plants in many countries worldwide. In Africa, this pest has spread rapidly and has become widely established since the first invasion report in 2003. Wolbachia is a vertically transmitted endosymbiont that can significantly influence aspects of the biology and, in particular, the reproduction of its host. In this study, we screened B. dorsalis specimens collected from several locations in Africa between 2005 and 20...

Antifeedant and ovicidal activities of a new cassane and other compounds from Caesalpinia welwitschiana Oliv. and Caesalpinia bonduc L. against Tuta absoluta (Lepidoptera: Gelechiidae).

Abstract: Methanolic extracts of liana of Caesalpinia welwitschiana and leaves of C. bonduc were found to possess moderate antifeedant and ovicidal activities against Tuta absoluta. Bioassay-guided isolation of constituents from the most active fraction of C. welwitschiana led to the identification of four known compounds [isobonducellin 1a and bonducellin 1 b, intricatinol 2, (-)-epigallocatechin-3-O-gallate 4] and one new constituent [welwitschianic acid 3]. The most active fraction of C...

Smallholder farmers’ knowledge and willingness to pay for insect-based feeds in Kenya

Abstract: Edible insects are increasingly being considered as sustainable alternatives to fish and soybean meals in animal feed because of their high nutritional quality and environmental benefits. However, successful introduction of a new product to the market depends on the target user’s acceptance. Thus, evaluating the potential demand of insect-based feeds would provide relevant information for policy development. The present study assessed farmers’knowledge on edible insects as feed...

Effect of Azadirachta indica and Milletia ferruginea extracts for Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) infestation management in chickpea.

Abstract: Nowadays, Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) is becoming a serious insect pest of chickpea in Ethiopia and its management has faced considerable challenges, to improve yields in many crops, in most parts of the world. This experiment was initiated with the objective to evaluate the effectiveness of Azadirachta indica and Milletia ferruginea extracts for the management of H. armigera in chickpea from July to December during 2017 and 2018 cropping season under fie...

Nitrogen fertilizer equivalence of black soldier fly frass fertilizer and synchrony of nitrogen mineralization for maize production

Abstract: The use of black soldier fly frass fertilizer (BSFFF) is being promoted globally. However,information on nitrogen (N) fertilizer equivalence (NFE) value and synchrony of N mineralization forcrop production remains largely unknown. Comparative studies between BSFFF and commercialorganic fertilizer (SAFI) were undertaken under field conditions to determine synchrony of N releasefor maize uptake. The BSFFF, SAFI, and urea fertilizers were applied at the rates of 0, 30, 60,and 100 kg N...

Chemistry and Sensory Characterization of a BakeryProduct Prepared with Oils from AfricanEdible Insects

Abstract: Globally, there is growing interest to integrate insect-derived ingredients into food products.Knowledge of consumer perception to these food products is growing rapidly in the literature,but similar knowledge on the use of oils from African edible insects remains to be established. In thisstudy, we (1) compared the chemistry of the oils from two commonly consumed grasshoppers,the desert locustSchistocerca gregariaand the African bush-cricketRuspolia differenswith those ofolive and...

Cannibalism, oviposition and egg development in the edible long-horned grasshopper, Ruspolia differens (Orthoptera Tettigoniidae) under laboratory conditions

Abstract: Reliance on seasonal wild harvests of the edible long-horned grasshopper Ruspolia differens (Serville) (Orthoptera: Tettigoniidae) needs to be broken through developing efficient mass rearing protocols. This study aimed at boosting productivity of laboratory colonies of R. differens through understanding ways of minimising cannibalism, selecting suitable oviposition substrates and enhancing egg development and hatchability. Firstly, we investigated the extent of cannibalism in a co...


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