Long‐term Effects of Pyrethrin and Cyfluthrin,a Type II Synthetic Pyrethroid,Insecticide Applications on Bull Reproductive Parameters

The objectives of this study were to determine effects of cyfluthrin and pyrethrin spray products, used in combination with cyfluthrin topical and ear tag applications, on bull reproductive parameters over 18 weeks. Angus or Angus x Simmental bulls were randomly assigned to one of three treatment groups: (i) no exposure to pyrethrins/cyfluthrin (CONT; n = 10), (ii) cyfluthrin ear tag and topical applications (ET; n = 10), or (iii) cyfluthrin ear tag, topical, premise spray and pyrethrin fog spray applications (ET+S; n = 8). Bull body weight was measured every 3 week, and body condition score and scrotal circumference were recorded on weeks 0, 9 and 18. Semen and serum were collected every 3 weeks for sperm evaluation and testosterone measurement, respectively. There was a treatment × week interaction (p < 0.01) for sperm with primary defects; bulls in CONT group had a greater (p = 0.01) percentage of sperm with primary defects than bulls treated with insecticides at week 18. Overall and progressive sperm motility, normal sperm morphology, secondary sperm defects and serum testosterone concentrations changed (p < 0.01) over time in all bulls; however, treatment did not affect (p ≥ 0.13) any of these parameters. There were also no treatment effects (p ≥ 0.08) on bull body weight, body condition score or scrotal circumference. The use of pyrethrin‐ and cyfluthrin‐based insecticides, regardless of application, did not negatively affect reproductive parameters in beef bulls when administered over 18 weeks.     

THE EFFECT OF POST-EMERGENCE HERBICIDES ON THE VEGETATIVE AND REPRODUCTIVE GROWTH OF CENTROSEMA FUBESCENS BENTH. IN QUEENSLAND

Summary. 2,4-D-amine, 2,4-D ethyl ester, 2.4-DB-potassium. MCPA-sodium, diquat and a 1:1 mixture of 2,4,5-T butyl ester and 2,4-D ethyl ester were applied to the tropical pasture legume Centrosema pubescens Benth. (centro) grown either alone or with Panicum maximum Jacq. (guinea grass). Even at 0.5 Ib/ac (total) the 2,4,5-T/2,4-D mixture caused severe damage to seedling and mature centro. 2,4-D-amine, 2,4-D ethyl ester and 2,4-DB-potassium were less damaging and there were only slight differences in response to these. Diquat at 0.25 Ib/ac desiccated centro seedlings, but most plants survived and grew satisfactorily. There was some evidence that the growth of mature centro was depressed least when the herbicides were applied during vegetative quiescence.
Application just after the start of flowering altered the flowering pattern but did not reduce seed yields significantly. 2,4-D-amine at 0.75 and 1–5 lb/ac and 2,4-D ethyl ester at 1.5 Ib/ac decreased the percentage germination of abraded seed. Diquat 0.25 Ib/ac applied at the start of flowering caused significant increases in top growth and seed pod numbers, possibly the result of modification of the normal flowering pattern.     

Seasonal and between-year variations of fish populations in the middle Thames estuary: 1980–1989

Fish samples collected at the cooling water intake screens of West Thurrock power station located 35.5 km downstream of London Bridge on the Thames estuary during the decade 1980–1989 were analysed. Seasonal and long-term changes in the abundance of the 15 most numerous fish species and in several fish community parameters were analysed. The majority of species were highly seasonal in their distribution and abundance. Species diversity was lower in the summer (May–August) compared with spring/winter (October–February). Evidence of long-term changes in species diversity and community structure over the decade is presented. The changes were consistent with a period of relative stability (1980–1984) followed by a period of change (1985–1989) and may reflect a deterioration in water quality in the second quinquennium. It is argued that the monitoring of fish communities in estuaries should be based on a multi-metric approach as no single indicator alone can describe the complex community structure.     

Differences in the extent of fungal development, host cell necrosis and symptom expression during race-cultivar interactions between Phaseolus vulgaris and Colletotrichum lindemuthianum

The cellular reactions of excised hypocotyl segments of 31 cultivars of Phaseolus vulgaris to infection by two races of Colletotrichum lindemuthianum were surveyed. Consistent differences in the extent of fungal development and host cell necrosis were used to establish six infection categories.
Extreme susceptibility (category 5) involved initial formation of infection vesicles in living epidermal cells and a prolonged period of intracellular biotrophic development prior to necrotrophic growth and production of spreading lesions. Extreme resistance (category 0) involved rapid death and browning of penetrated epidermal cells, without formation of infection vesicles or a detectable biotrophic phase. Fungal growth and host necrosis were limited to single epidermal cells. Intermediate reactions (categories 1 to 4) initially resembled category 5, but after a biotrophic phase of varying duration, infected cells and some adjacent uninfected cells died and became brown, and fungal growth ceased. Symptoms ranged from flecks (small groups of dead cells) to large areas of necrosis (limited lesions). Similar intermediate reactions also occurred in normally susceptible hypocotyls which were transferred from 17 to 25°C, or which retained cotyledons.
The finding that resistance is expressed at different stages of infection is discussed in relation to the regulation of cultivar specificity.     

FOCAL INCREASED RADIOPHARMACEUTICAL UPTAKE IN THE DORSOPROXIMAL DIAPHYSEAL REGION OF THE EQUINE PROXIMAL PHALANX

The aims of this study were to establish the frequency of occurrence, intensity and symmetry of focal increased radiopharmaceutical uptake in the dorsoproximal aspect of the diaphysis of the proximal phalanx; to determine if this focal increased radiopharmaceutical uptake was related to age, height, gender, breed, bodyweight, or discipline of the horse, and if there was any relationship with lameness. Scintigraphic images from 690 horses were analyzed subjectively and objectively. Age, breed, discipline, height, weight, gender, and lame limb(s) or reasons for presentation were recorded for all horses. Univariate and multivariable logistic regression was performed to identify associations between available variables and focal increased radiopharmaceutical uptake. Focal increased radiopharmaceutical uptake was present in 17% of forelimbs and 7% of hindlimbs. It occurred most frequently in the forelimbs of older, taller, and heavier warmblood and warmblood cross dressage horses, and the hindlimbs of older, taller, and heavier showjumpers and dressage horses. It was usually bilaterally symmetrical and was not associated with lameness.