Long-term impacts of an organophosphate-based regime of pesticides on field and field-edge Collembola communities

During a 6-year study, effects of two contrasting regimes of pesticide use on pitfall and suction catches of Collembola were monitored in an arable field under a rotation of grass and winter wheat. Current farm practice (CFP) represented conventional fungicide and herbicide use plus applications of organophosphorus (OP) insecticides, whereas reduced input approach (RIA) utilised minimum inputs of fungicides and herbicides and excluded any use of insecticides. Compared with RIA, the CFP regime caused a substantial decline in the abundance and diversity of Collembola in the field, including the local disappearance of one species, without recovery during the study. At the field edge, which was protected during OP applications by a 6-m unsprayed buffer zone, effects of the CFP regime were less severe, and were not persistent in the long term. Some Collembola species occurred only in field-edge samples. Pitfall and suction sampling yielded remarkably similar patterns of catches, indicating that pitfall trapping may be appropriate for detecting long-term changes in collembolan abundance caused by intensive agricultural management practices.     

Spatial and temporal characteristics of dicarboximide-resistant strains of Monilinia fructicola and brown rot incidence in stone fruit

The spatial and temporal distribution of dicarboximide-resistant strains of Monilinia fructicola were investigated in six peach and nectarine orchard blocks in 1987–89 using a dispersion index (Lloyd's Patchiness Index, LPI), and spatial, temporal and spatio-temporal autocorrelation analyses (Moran's Coefficient, I ). The LPI values indicated that resistant strains were aggregated in all blocks in all years. Spatial correlations were not significant beyond one quadrat for any spatial proximity pattern in five of six blocks. Thus the spread of resistant strains was mostly restricted to the vicinity of the original focus. An absence of significant temporal correlation between years in five of the six blocks indicated poor persistence of resistant strains at specific locations. Only one significant temporal correlation was detected at one block and this could have arisen by chance. Significant spatio-temporal correlation was not detected, suggesting that there was no focus expansion or carry-over of resistant strain inoculum from the previous sampling date. Spatial, temporal and spatio-temporal autocorrelation analyses were consistent with previously reported laboratory results that resistant strains had not acquired all the necessary characteristics to remain in, or dominate, field populations. The spatial pattern of brown rot incidence was investigated at one block in a separate study in 1988 and 1989. There were no significant spatial correlations for brown rot incidence in 1988 for any of the spatial proximity patterns analysed. In 1989, however, significant correlations indicated ellipsoid aggregates of brown rot orientated along the orchard rows.     

Assessment of Different Functional Parameters of Frozen–Thawed Buffalo Spermatozoa by Using Cytofluorimetric Determinations

Flow cytometry is a useful tool that provides an accurate, objective and rapid evaluation of semen quality. The use of this technique could significantly improve the quality of buffalo semen samples used in artificial insemination. This study was carried out to evaluate, by flow cytometry, frozen–thawed buffalo spermatozoa quality parameters such as sperm viability by SYBR‐14/propidium iodide staining; mitochondrial function by JC‐1 potentiometric probe; sperm chromatin stability (SCSA) by acridine orange; and acrosome reaction (AR) by FITC‐PNA staining. Semen samples from five Italian Mediterranean buffalo bulls were used. Sperm viability was not different between bulls and ranged from 33.4% to 43.6%. A consistent rate (55.1 ± 10.8%) of sperm cells showed high mitochondrial membrane potential (Δψ^high), with no significant differences between subjects. Sperm chromatin structure assay differed significantly between the five buffalo bulls; moreover, data showed high stability within each buffalo. DNA fragmentation indexes (DFI), such as %‐DFI, ‐DFI, SD‐DFI, were 11.2 ± 8.6, 153.3 ± 24.6 and 81.6 ± 21.2, respectively. Regarding AR, the percentage of acrosome‐reacted live (ARL) and acrosome‐reacted dead (ARD) spermatozoa was 0.3 ± 0.2 and 15.3 ± 5.5, respectively. This functional parameter differed significantly between buffalo bulls and showed high stability. Following to Ca²⁺ ionophore A23187 for 3 h, AR significantly differed between subjects and was characterized by an increase in both ARL (10.8%) and ARD population (22.0%). This study indicates that flow cytometry could be a useful tool for a quick multiparametric evaluation of sperm quality in buffalo. In particular, SCSA and AR resulted in sperm functional parameters sensitive enough for the diagnosis of frozen‐thawed semen fertilizing potential.