Mark A. Curtis

Effects of Eubothrium salvelini (Cestoda) on the behaviour of Cyclops vernalis (Copepoda) and its susceptibility to fish predators

To facilitate the completion of their life-cycle, many helminth parasites have evolved the ability to manipulate the behaviour of their intermediate host in order to make it more likely to be eaten by the parasites definitive host. Here, we determined whether the cestode Eubothrium salvelini modifies the behaviour of its intermediate host, the copepod Cyclops vernalis , and makes it more susceptible to predation by brook trout, Salvelinus fontinalis , the parasites final host. Following the experimental infection of copepods, the spontaneous activity of infected and control subjects was quantified weekly. In addition, we regularly quantified predation by individual brook trout fry on known numbers of infected and control copepods. At approximately the time when the cestode larvae became infective to fish (2–3 weeks following infection), the infected copepods started to swim more actively than uninfected controls. Also at that time, infected individuals became more likely to be captured by fish than uninfected ones. Copepod size and intensity of infection had no significant effect on their behaviour or their risk of being eaten by fish. Thus cestode- induced changes in copepod swimming activity can lead to infected copepods becoming highly vulnerable to fish predators, and may have resulted from selection on the parasite to increase its transmission success

Parasite-induced susceptibility to predation in diplostomiasis

Guppies ( Lebistes reticulatis ) exposed to doses as low as 25 cercariae of Diplostomum spathaceum for 30 min were consistently and significantly more susceptible to predation by brook trout ( Salvelinus fontinalis ) than uninfected controls. The increase in susceptibility to predation was correlated with a marked decrease in the activity of infected fish.

Infection of brook trout fry, Salvelinus fontinalis, by ectoparasitic copepods: the role of host behaviour and initial parasite load

Abstract Ectoparasitic copepods tend to aggregate on their fish hosts, with few fish harbouring many parasites and most fish harbouring few or none. In laboratory experiments, it was determined whether individual differences in behaviour among uninfected hosts, and parasite-induced behavioural changes in infected hosts, act to generate aggregated distributions of the copepod Salmincola edwardsii on brook trout fry. Fish were individually exposed to parasites twice, first to numbers ranging from 0 to 80 copepods, to produce variability in initial parasite load, and then to 40 copepods. Fish behaviour was significantly affected by the presence of copepods in the surrounding water in both exposures. However, there was no clear relationship between copepod density and host behaviour. Among uninfected fish exposed to copepods for the first time, the number of copepods acquired by a fish was inversely related to the time it spent motionless. Prior infection increased the probability that a fish would acquire further copepods during a subsequent exposure. This may be due to copepod-induced behavioural changes, since the time spent motionless by fish decreased as the number of copepods harboured increased. This suggests that behavioural differences among uninfected hosts, and greater risks of acquiring further parasites through behavioural changes in infected hosts, could lead to few fish harbouring most parasites in natural populations.

Size, behaviour, and acquisition of ectoparasitic copepods by brook trout, Salvelinus fontinalis

In natural fish populations, most hosts harbour few or no ectoparasitic copepods, while most copepods are concentrated on a few hosts. In laboratory experiments, we determined whether such aggregated distributions of the copepod Salmincola edwardsii could result from variability on the behaviour and/or size of their host, the brook trout Salvelinus fontinalis. Using trout varying widely in size, we exposed small groups of individually marked fish to copepods for 2-5 wk in a tank were the parasites were released upstream in a weak current

Knowledge integration and the adoption of new agricultural technologies: Kenyan perspectives

Despite gains in agricultural yields, access to food remains a serious challenge in many parts of the world. It is now recognized that improving food security requires a more integrated understanding of food systems and that key under-explored areas of these systems are likely to be crucial in developing effective policy change. In Kenya, institutional changes have occurred to facilitate knowledge integration within the agricultural sector. Drawing on the experiences and understandings of key stakeholders in Kenya, this paper aims to identify and better understand the barriers to knowledge integration for improved agricultural technologies and their adoption. A number of barriers to the flow of knowledge to and from those working to develop new agricultural technologies and farmers are identified. The results of this study suggest a potential link between farmers’ levels of community organization and levels of trust with levels of knowledge integration surrounding agricultural technologies and their adoption. The findings suggest that increasing the planning and follow-up of newly introduced agricultural technologies has the potential to encourage interdisciplinary approaches and improve food security outcomes.

ENVIRONMENTAL ASSESSMENT IN MULTILATERAL DEVELOPMENT BANK INTERMEDIARY LENDING

A substantial portion of private sector investments in emerging market economies internationally is routed through the use of Financial Intermediaries (FIs). FIs act as important gateways for channeling the resources from large Multilateral Development Banks (MDBs), to micro, small and medium-sized (SME) projects and enterprises whose comparatively limited business portfolios would otherwise make them ineligible for funding. During a MDBs scoping, FI clients are classified into a unique Category FI, whereby the onus for Environmental Assessment (EA) is transferred from the MDB to the FI. Although EA guidelines exist, FI institutions often fail to adequately incorporate them in their sub-project review. This increases the potential for environmentally and socially harmful development decisions being made by the FI with financial resources originating from MDBs. This paper identifies the factors limiting the successful incorporation of EA in FI subproject financing, in an attempt to develop tools to assist MDBs and their FIs to attain compliance with local, national and international EA laws and regulations.