Changes in wheat bulb fly (Delia coarctata) populations in East Anglia in relation to crop rotations, climatic data and damage forecasting

Records of wheat bulb fly egg (Delia coarctata) population densities in fields sampled throughout East Anglia in the autumns of 1953–1990 are presented. In descending order of risk, fallow, potato, pea (mainly vining), sugar beet and oilseed rape are the main crops preceding wheat or barley which attract oviposition. A declining trend of egg populations observed over the study period may be associated with climatic changes as well as with the elimination of fallow in the rotation and the dramatic increase in the use of insecticides against the pest. Negative correlations (P < 0.05) in mean annual egg numbers were found with departures from average of July temperature and January air or soil temperature; positive correlations (P<0.05) with departure from average of August raindays. Stepwise regression analysis was used to identify the most important relationships of meteorological variables with mean annual egg numbers, or the proportion of fields sampled with egg numbers in excess of the action threshold of 2.5 million eggs/ha. Up to 59% of the variation in the annual proportion of fields above threshold was accounted for in a regression equation using departures from average of July temperature, August raindays and the percentage of average of October (preceding year) rainfall. Estimated mean annual egg populations and the proportion of fields above threshold showed a good fit with the observed values. The findings are discussed and compared with previous work. The forecasting model may be readily incorporated as a regional risk-prediction component of a knowledge-based system for the management of wheat bulb fly control. Regional forecasts of wheat bulb fly oviposition from this work should be tested and modified as necessary according to experience or changing climatic or agricultural factors.     

Do wild dogs exclude foxes? Evidence for competition from dietary and spatial overlaps

Abstract The management of wild canids (wild dogs/dingoes and foxes) presents a conservation dilemma for land managers across Australia. These canids are predators of wildlife and domestic stock but dingoes are considered native and anecdotal reports suggest that they may suppress foxes such that dingo/dog conservation may have a net benefit to wildlife. This study examines dietary and spatial interactions between wild dogs and foxes in the Greater Blue Mountains region of NSW to address the possibility of suppression through competitive exclusion by dogs on foxes. Predator diets were compared using faecal analysis as well as an analysis of 19 dietary studies from similar forest habitats in eastern Australia. Spatial relationships were examined using data from an extensive canid control programme. Diets of wild dogs and foxes showed a high degree of overlap in species taken, indicating potential for competition. But there was also evidence of resource partitioning with the size and arboreality of mammalian prey differing between the two predators. Wild dogs and foxes responded to different landscape‐scale variation in the physical environment, but there was no clear evidence of large‐scale differences in their distribution. At the fine scale there was a negative association between these predators that indicated possible temporal avoidance or localized habitat shifts. Therefore, there is evidence for dietary competition and fine‐scale exclusion, but no support for landscape‐scale exclusion of foxes by wild dogs in the Blue Mountains.     

Distribution of Oriental and German cockroaches, Blatta orientalis and Blattella germanica (Dictyoptera), in the United Kingdom

Results are presented of a survey carried out by Rentokil Ltd on the distribution of the Oriental cockroach Blatta orientalis L. and the German cockroach Blattella germanica L. in the United Kingdom. The known ranges of both species are increased considerably by the findings of the survey, with several new vice-county records for Scotland (including the Western Isles), England and Wales. The frequency at which Blatta orientalis was observed in outdoor habitats may indicate that this species sometimes spreads to new areas without human assistance.     

Filamentous organisms in benign and malignant gastric cytology brushings

Review of 143 gastric brushing specimens from two centres in patients with a subsequent histological diagnosis on biopsy or gastrectomy specimens revealed filamentous organisms (FOs) in a large number of benign and malignant gastric brushings. The presence of FOs in significant numbers of brushings of benign gastric lesions contradicts the previously reported strong association of FOs with only gastric carcinoma, and questions the importance of finding these organisms in gastric brushing and biopsy material.     

Fiber Ultrastructure and Contraction Kinetics in Insect Fast Muscles

SYNOPSIS. Isometric contraction kinetics were measured and fiberstructure was quantified in tymbal muscles from different cicadaspecies. Twitch duration is directly correlated with the sizeof the myofibrils and with the ratio of the fraction of fibervolume which is myofibril to that which is sarcoplasmic reticulum(SR) and T-tubules (fast muscles have small myofibrils and arelatively large volume of SR and T-tubules). Twitch durationis not significantly correlated with fiber size, with sarcomerelength, nor with the fractional volume of the fibers which ismitochondria, indicating that these structural features arenot strongly involved in the determination of isometric contractionkinetics. In the tettigoniid Neoconocephalus robustus, twitchesfrom forewing muscles of male animals become progressively shorterover the first five days following the adult molt. This changein contraction kinetics is associated with an increase in therelative volume of SR and T-tubules. Denervation blocks theacquisition of rapid kinetics, indicating that neural inputis necessary for this transformation.