Abstract
The role of carabid beetles in reducing populations of phytophagous insects has been an elusive subject. A field experiment was established on a commercial wheat crop (cv. Otto) with an area of 4.5 ha in Valdivia, Chile, during the spring and summer of 1996-1997. The field had been under a prairie system for two years, before wheat sowing (fertilization and a pesticide had been applied during crop development). Samples were taken at approximately monthly intervals. Carabid beetles were sampled with a grid of pitfall traps and other insects were sampled with a vacuum insect net and soil cores. The genera of the carabids found are of neotropical origin. Exclusion by polythene barriers, together with removal of carabid beetles using traps, was an effective technique for controlling carabid populations in a commercial wheat crop. A reduction in the number of carabid beetles was associated with an increase in the number of springtails and arachnids, and a decrease of agromyzid adults. Phytophagous insects, such as homopterans and lepidopterous larvae, were not affected by carabid exclusion and removal. The action of carabid beetles on the arthropod fauna can be extremely complex, due to its predatory activity at multitrophic levels.
Highlights
The role of carabid beetles in reducing populations of phytophagous insects has been an elusive subject
The main aim of the present study is to evaluate the effect of carabid beetles on the wheat arthropod fauna by manipulating beetle abundance
Total number of carabid beetles caught in each pitfall traps in each of the tion was obtained by digging treatments; Exclusion y-y exclusion and removal ∆-∆ and control Ο-Ο
Summary
The role of carabid beetles in reducing populations of phytophagous insects has been an elusive subject. A field experiment was established on a commercial wheat crop Together with removal of carabid beetles using traps, was an effective technique for controlling carabid populations in a commercial wheat crop. A reduction in the number of carabid beetles was associated with an increase in the number of springtails and arachnids, and a decrease of agromyzid adults. Phytophagous insects, such as homopterans and lepidopterous larvae, were not affected by carabid exclusion and removal. The role of carabid beetles in reducing populations of phytophagous insects has been a very elusive subject. Lövei and Sunderland (1996), the effectiveness of a natural enemy can be established following four sequential steps: (1) evaluating dynamics and correlating predator and prey density, (2) obtaining evidence of a trophic link between the prey and the predator, (3) manipulating predator numbers and the effect on prey density, and (4) integrating the above information to quantify the effect of predator on prey
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