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Lady beetles (Coccinella septempunctata) are one of the most effective predators of aphids (Sitobion avenue). Therefore, the development of plant protection technologies that do not lead to their eradication within the field is necessary. With a sensorcontrolled field sprayer, which determined in real-time the plant biomass of a heterogeneous winter wheat field and, based on these measurements, also controlled the amount of applied insecticide, a variable rate spraying program was implemented. The insecticide savings totaled 13.4% when compared to that of uniform spraying. An application of a high dosage led to a rapid die-off of aphids. However, this same scenario did not occur in the areas that received a low dosage of insecticide. There, the aphids remained alive. It was observed that lady beetles colonized at first in these low dosage areas, where aphids were still present. Eventually 3 wk after insecticide application, aphids and lady beetles did not exist in the areas that received low insecticide dosages in the field. There, at this latter time the crop was mature. Now the aphids occurred in the high biomass areas, which were still green and not fully mature. The same scenario occurred for the lady beetles; as presence-absence sampling indicated that they followed their prey. The time-dependent spatial variability of aphid and lady beetle occurrence were confirmed by GLIMMIX analysis which indicated a significant effect of the space-time interaction on their joint occurrence. [ABSTRACT FROM AUTHOR]

Laser rangefinders and laser scanners are widely used for industrial purposes and for remote sensing. In agriculture information about crop parameters like volume, height, and density can support the optimisation of production processes. In scientific papers the measurement of these parameters by low cost laser rangefinders with one echo has been presented for short ranges. Because the cross section area of the beam increases with the measuring range, it can be expected that laser rangefinders will have a reduced measuring accuracy in small sized crops and when measuring far distances. These problems are caused by target areas smaller than the beam and by the beam striking the edges of crop objects. Lab tests under defined conditions and a real field test were performed to assess the measuring properties under such difficult conditions of a chosen low cost sensor. Based on lab tests it was shown that the accuracy was reduced, but the successful use of the sensor under field conditions demonstrated the potential to meet the demands for agricultural applications. Insights resulting from investigations made in the paper contribute to facilitating the choice or the development of laser rangefinder sensors for vehicle based measurement of crop parameters for optimisation of production processes. [ABSTRACT FROM AUTHOR]