Results from a field study to monitor effects of Spinosad on the natural community in an apple orchard

Spinosad (NAF-85) (SC, 480g/l) is an insecticide derived naturally from a bacteria through fermentation. It is active against a variety of insect pests, especially caterpillars, and is an interesting candidate to be used in orchards to control e.g. leafrollers and codling moth. Spinosad is known to be rather selective to many predators. According to own investigations and considering different exposure routes, Spinosad, has revealed to be harmless for Chrysoperla carnea and Coccinella septempunctata. There exist however data that it can harm parasitoids. The objective of our field study, carried out in 2000 and 2001, was to monitor potential effects of Spinosad on the natural community of arthropods on apple trees, when used as insecticide to control the leafroller Adoxophyes orana. According to the recommendations of the supplier (Dow AgroSciences) in 2000, the application against the first generation of A.orana was splitted and within one week at the end of June two treatments, each with 100 ml Spinosad/ha, took place. In 2001 two treatments per A. orana generation were made with 200 ml/ha in June/July and August. As reference product ME 605 Spritzpulver (WP, a.i. 405g methylparathion/kg ) was used (500 ml/ha), the control plot was sprayed with water. Plot size per treatment was 0.2 ha. The apple fauna was assessed with beating samples: five samples per treatment and 25 branches per sample at each sampling date. Beating samples were taken one day before and one day after each treatment, as well as two weeks and four weeks after the last treatment. Arthropods collected with the beating samples covered a wide range of taxa. However only few groups were present in constant higher abundances. These were especially Araneae, mites (Anystidae, Oribatei), Dermaptera (Forficula. auricularia), Formicidae (Lasius niger) and Cicadellidae. In comparison to the water treated control, the abundance of arthropods of most taxa was not or only slightly reduced in the Spinosad treatment. In contrast, the toxic compound resulted in clearly reduced numbers of some arthropod groups