Environmental & Physical Sciences

Research Papers/Topics Environmental & Physical Sciences

Old and new host-parasitoid associations: parasitism of the invasive fruit fly Bactrocera invadens (Diptera: Tephritidae) and five African fruit fly species by Fopius arisanus, an Asian opiin

Abstract: Fopius arisanus (Sonan), a solitary koinobiont endoparasitoid of fruit flies, was introduced for testing and final release against the recently discovered species Bactrocera invadens Drew, Tsuruta and White in Africa. Laboratory experiments were conducted to assess host preference, host acceptability for oviposition, and physiological suitability of B. invadens and five other indigenous tephritid fruit fly species, namely, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), C. c...

Insects for sustainable animal feed: inclusive business models involving smallholder farmers

Abstract: Global population growth, an increasing demand for animalproducts and scarcity of conventional feed ingredients drivethe search for alternative protein sources for animal feed.Extensive research indicates that insects provide goodopportunities as a sustainable, high quality and low-costcomponent of animal feed. Here, we discuss how insectfarming can promote inclusive business for smallholder farmersin the agribusiness value chain. Inclusive business modelsinvolving insects as ingre...

Lepidopteran stem borer species abundance and associated damages on irrigated Kilombero low land rice ecosystem in Tanzania

Abstract: Background: Rice stem borers are among the most biotic stresses of economic importance in agriculture. Little was known about stem borer problem in Tanzania prior to this study. Understanding stem borer abundance and damages would help to design appropriate stem borer integrated pest management strategy in rice. This study was aimed at investigating rice stem borerʼs species abundance and their associated damages in irrigated lowland rice ecosystem in Kilombero Tanzania. Materials...

Distribution of rice stem borers and their parasitoid in irrigated low land rice ecosystem in Kilombero valley, Morogoro, Tanzania

Abstract: Distribution of rice stem borers and their parasitoid, in irrigated low land rice ecosystem in Kilombero district, Morogoro, Tanzania was studied from March – July 2017 in randomly sampled thirty rice fields. Rice stem borer larvae was sampled at two growth stages of rice, the vegetative stage and reproductive stage using 1m2 quadrat. The study revealed the presence of one species of parasitoid from family braconidae (Cotesia flavipes) which was found parasitizing the stem borer ...

Importance of Remotely-Sensed Vegetation Variables for Predicting the Spatial Distribution of African Citrus Triozid (Trioza erytreae) in Kenya

Abstract: Citrus is considered one of the most important fruit crops globally due to its contribution to food and nutritional security. However, the production of citrus has recently been in decline due to many biological, environmental, and socio-economic constraints. Amongst the biological ones,pests and diseases play a major role in threatening citrus quantity and quality. The most damaging disease in Kenya, is the African citrus greening disease (ACGD) or Huanglongbing (HLB) which is tra...

Transcriptional responses of Anopheles gambiae s.s mosquitolarvae to chronic exposure of cadmium heavy metal [version 1;referees: 2 approved with reservations]

Abstract: Background: Anopheles gambiae larvae traditionally thrive in non-polluted environments. We previously documented the presence of the larvae in heavy metal polluted urban aquatic environments and the associated biological cost. The goal of this study was to unravel the molecular dynamics involved in the adaptation of the mosquitoes to the heavy metals. Methods: Total RNA was extracted from third instar larvae of both cadmium treated populations and untreated control populations. The...

Relative influence of host, Wolbachia, geography and climate on the genetic structure of the subSaharan parasitic wasp Cotesia sesamiae

Abstract: The parasitoid lifestyle represents one of the most diversified life history strategies on earth. There are however very few studies on the variables associated with intraspecific diversity of parasitoid insects, especially regarding the relationship with spatial, biotic and abiotic ecological factors. Cotesia sesamiae is a Sub-Saharan stenophagous parasitic wasp that parasitizes several African stemborer species with variable developmental success. The different host-specialized p...

Role of egg-laying behavior, virulence and local adaptation in a parasitoid’s chances of reproducing in a new host

Abstract: Understanding the ability of parasitoid insects to succeed in new host populations is a relevant question forbiological control and adaptive mechanisms.Cotesia typhaeis an African parasitoid specialized on the mothSesamiae nonagrioides, also called the Mediterranean corn borer. Two Kenyan strains ofC. typhaediffer in theirvirulence against a new host population from France. We explored behavioral and physiological hypothesesabout this differentiation.Cotesiagenus belongs to a group...

Economic impacts of fall armyworm and its management strategies: evidence from southern Ethiopia

Abstract: This paper explores the economic implications of fall armyworm (FAW) and its management strategies by exploiting exogenous variation in FAW exposure amongst households in southern Ethiopia. We find that FAW exposure affects maize yield and sales negatively, but not consumption. Furthermore, we find evidence of crowding in and intensification of insecticide use in response to FAW exposure. We also find suggestive evidence that existing extension service arrangements lack the capacit...

Temperature-dependent development and survival of immature stages of the coffee berry borer Hypothenemus hampei (Coleoptera: Curculionidae).

Abstract: Although the coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae) is the most destructive insect pest of coffee worldwide, there is much to learn about its thermal biology. This study aimed to develop temperature-based models for H. hampei development and to provide the thermal requirements of immature stages in the laboratory. Using a new observation method, larval development and survival were monitored daily on fresh Arabica coffee seeds, und...

Low-cost technology for recycling agro-industrial waste into nutrient-rich organic fertilizer using black soldier fly

Abstract: Efforts to recycle organic waste using black soldier fly (BSF) larvae into high-quality alternative proteinbingredients in animal feeds and organic fertilizers have gained momentum worldwide. However, there is limited information on waste manipulation to increase nutrient retention for enhanced larval perfor mance and frass fertilizer quality. In the present study, brewer’s spent grain with a carbon to nitrogen (C/ N) ratio of 11 (control) was amended with sawdust to obtain subst...

Evaluation of The Magnitude of Citus Yield Losses Due to African Citrus Triozid, False Codling Moth, the Greening Disease and Other Pests of Economic Importance in Kenya

Abstract: Pests and diseases have continued to hamper productivity of the horticultural inductry round the globe. The Kenyan citrus industry is no exemption with a huge decline on its perfomance over the last decade. Although faced with numerous challenges including low productivity, inadequate capacity to buy farm inputs, lack of improved crop varieties, insect pests and diseases are cited to be the most appalling attribute to the decline in citrus productivity. Key among them are the Afric...

The invasion of the dwarf honeybee, Apis florea, along the river Nile in Sudan

Abstract: The spread of the dwarf honeybee, Apis florea, in Sudan along the river Nile in a linear fashion provides a good model for studying the population dynamics and genetic effects of an invasion by a honeybee species. We use microsatellite DNA analyses to assess the population structure of both invasive A. florea and native Apis mellifera along the river Nile. The invasive A. florea had significantly higher population densities than the wild, native A. mellifera. Nevertheless, we found...

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...


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