In agriculture, chemical insecticides are widely used to protect crops from insect pests. Over a period of years, some insects such as Colorado potato beetle （CPB） succeed in developing resistance to most of the reg...In agriculture, chemical insecticides are widely used to protect crops from insect pests. Over a period of years, some insects such as Colorado potato beetle （CPB） succeed in developing resistance to most of the registered chemical insecticides. Consequently, heavy applications of chemical insecticides to control this pest become ineffective on a long-term basis and can lead to serious health and environmental problems. The use of natural enemies to control CPB is an interesting alternative to chemical means However, hand release of predators is not feasible on a large scale in the field. The main objective of this research study was to design and build a test bench to investigate the technical feasibility of mechanically releasing predators. The test bench consisted of a vertical chain conveyor mounted on two vertical shafts driven by an electric motor. Since the predators are small and fragile, they were placed in a specially designed container to preserve their physical integrity. Trials using this test bench showed that a carrier material was required, because most of the predators remained inside the container. The success of this mass predator release system will be highly valuable for the biological control of insect pests in many crops.展开更多
Shoaling behavior provides numerous fitness benefits for fish, including enhanced access to mates, increased success in foraging and protection from predators. We were interested in determining whether shoaling intens...Shoaling behavior provides numerous fitness benefits for fish, including enhanced access to mates, increased success in foraging and protection from predators. We were interested in determining whether shoaling intensity differed throughout the day. To do this we kept adult zebrafish Danio rerio in different lighting conditions for 10 days： ＂Normal＂ （12：12LD, lights on at 0800 hrs）, ＂Reverse＂ （12：12LD, lights on at 2000 hrs）, DD, or LL, and then observed the shoaling behavior at different times during the day. Our findings suggest that daily variations exist in shoaling behavior, with mean shoaling times for fish from the ＇normal＇ group being the lowest at the mid-point of the dark phase in the fish＇s subjective day （00：00 hrs）, then rising signifi- cantly throughout the day, reaching their highest intensity at 20：00 hrs （lights out）. Fish from the ＂reverse＂ LD cycle （lights on at 20：00 hrs） showed differences in the mean shoaling times at different times of day, but did not show a gradual increase in shoaling throughout their subjective day. Fish from the DD and LL groups did not show significant differences in the mean shoaling values at different times of day, suggesting that the differences observed in LD fish may not represent circadian rhythms. Therefore, these results demonstrate the existence of daily variations in the shoaling behavior of fish and suggest that environmental cues in the form of light/dark cycles play an important role in regulating these variations [Current Zoology 58 （1）： 129-137, 2012].展开更多
文摘In agriculture, chemical insecticides are widely used to protect crops from insect pests. Over a period of years, some insects such as Colorado potato beetle （CPB） succeed in developing resistance to most of the registered chemical insecticides. Consequently, heavy applications of chemical insecticides to control this pest become ineffective on a long-term basis and can lead to serious health and environmental problems. The use of natural enemies to control CPB is an interesting alternative to chemical means However, hand release of predators is not feasible on a large scale in the field. The main objective of this research study was to design and build a test bench to investigate the technical feasibility of mechanically releasing predators. The test bench consisted of a vertical chain conveyor mounted on two vertical shafts driven by an electric motor. Since the predators are small and fragile, they were placed in a specially designed container to preserve their physical integrity. Trials using this test bench showed that a carrier material was required, because most of the predators remained inside the container. The success of this mass predator release system will be highly valuable for the biological control of insect pests in many crops.
文摘Shoaling behavior provides numerous fitness benefits for fish, including enhanced access to mates, increased success in foraging and protection from predators. We were interested in determining whether shoaling intensity differed throughout the day. To do this we kept adult zebrafish Danio rerio in different lighting conditions for 10 days： ＂Normal＂ （12：12LD, lights on at 0800 hrs）, ＂Reverse＂ （12：12LD, lights on at 2000 hrs）, DD, or LL, and then observed the shoaling behavior at different times during the day. Our findings suggest that daily variations exist in shoaling behavior, with mean shoaling times for fish from the ＇normal＇ group being the lowest at the mid-point of the dark phase in the fish＇s subjective day （00：00 hrs）, then rising signifi- cantly throughout the day, reaching their highest intensity at 20：00 hrs （lights out）. Fish from the ＂reverse＂ LD cycle （lights on at 20：00 hrs） showed differences in the mean shoaling times at different times of day, but did not show a gradual increase in shoaling throughout their subjective day. Fish from the DD and LL groups did not show significant differences in the mean shoaling values at different times of day, suggesting that the differences observed in LD fish may not represent circadian rhythms. Therefore, these results demonstrate the existence of daily variations in the shoaling behavior of fish and suggest that environmental cues in the form of light/dark cycles play an important role in regulating these variations [Current Zoology 58 （1）： 129-137, 2012].
