Mitigating epidemics caused by non-persistently transmitted aphid-borne viruses: the role of the pliant environment.

Using Soybean mosaic virus as a model system, the rate, magnitude and timing of epidemics caused by non-persistently transmitted, aphid-borne viruses are examined under various field conditions. Emphasis is placed on the behavioural responses of vectors to environmental cues, although all three biotic components (host plant, vector and virus) are considered. Both single and double manipulations of the cropping system environment are explored using a computer model developed earlier by Ruesink and Irwin (Plant Virus Epidemics: Monitoring, Modelling and Predicting Outbreaks.

High carbon dioxide tension (PCO2) and the incidence of cardiac arrhythmias in rapidly growing broiler chickens.

The purpose of this investigation was to determine whether two-week-old rapidly growing broiler chickens with high metabolic activity have an increased risk of the development of heart failure three to five weeks later. The incidence of cardiac arrhythmias was assessed in broiler chickens with either a relatively high carbon dioxide tension (PCO2) or a low PCO2 in their venous blood. Their electrocardiograms (ECGS) were measured when the birds were between five and seven weeks old by means of a biotransplant which allowed them to move freely.

Heart rate variability during manual restraint in chicks from high- and low-feather pecking lines of laying hens.

The purpose of this investigation was to determine whether there is a difference in coping style in chicks from a high (HFP)- and low-feather pecking (HFP) line of laying hens. Active and passive coping styles can be distinguished by differences in sympathetic and parasympathetic activities on the heart. We studied heart rate during baseline conditions and during manual restraint in HFP and LFP hens.

Plasma catecholamine and corticosterone levels during manual restraint in chicks from a high and low feather pecking line of laying hens.

Neurosympathetic and adrenal responsivity to manual restraint was studied in two White Leghorn chicken lines which differ in their tendency to feather peck. Blood samples were taken from freely moving cannulated birds during resting conditions and during manual restraint (placing the bird on its side for 8 min) to determine plasma noradrenaline. adrenaline and corticosterone.

Estimating maximum horizontal area of pheromone plumes.

Graphs and simple Gaussian plume equations are presented for estimating the maximum horizontal area within a pheromone plume. In its simplest form the area,A R , for a given scaling factor,R = Q/(Ku), isA R = AI R (β), whereQ is the release rate,K is a specified concentration threshold,u is the wind velocity, and β is an atmospheric stability index. Estimates ofA I and β are given for several atmospheric stability typing schemes applicable to field and forest habitats.