PURE – Deliverable D10.5 Funded by the European Union PURE Pesticide Use-and-risk Reduction in European farming systems with Integrated Pest Management Grant agreement number: FP7-265865 Collaborative Project SEVENTH FRAMEWORK PROGRAMME D10.5 Recommendation of manipulation of field margins Due date of deliverable: M 48 Actual submission date: M 48 Start date of the project: March 1st, 2011 Duration: 48 months Workpackage concerned: WP 10 Concerned workpackage leader: Graham Begg Organisation name of lead contractor: AU Project co-funded by the European Commission within the Seventh Framework Programme (2007 - 2013) Dissemination Level PU Public PU PP Restricted to other programme participants (including the Commission Services) RE Restricted to a group specified by the consortium (including the Commission Services) CO Confidential, only for members of the consortium (including the Commission Services) Page 1 of 33 PURE – Deliverable D10.5 Table of contents 1. Summary _____________________________________________________________ 3 2. Objectives _____________________________________________________________ 3 3. Deliverable procedure ___________________________________________________ 3 3.1 Experiments in Denmark ______________________________________________________ 3 3.1.1. Arthropod sampling methods ______________________________________________________ 4 3.1.2. Quantifying predation intensity ____________________________________________________ 4 3.2. Experiments in the U.K. ____________________________________________________ 5 3.2.1. Pitfall trapping – ground active arthropods ___________________________________________ 7 3.2.2. Vortis suction sampling- aerial arthropods ___________________________________________ 7 3.2.3. Aphid counts ___________________________________________________________________ 7 3.2.4. Exclusion cage experiment ________________________________________________________ 7 3.2.5. Assessment of parasitism activity in oilseed rape ______________________________________ 8 4. Results summary ________________________________________________________ 8 5. Conclusions ___________________________________________________________ 10 Appendix 1 Poster presented at the PURE conference IPM Innovation in Europe 2015 ___ 11 Appendix 2 Abstract of Poster presentation at the PURE conference2015 _____________ 12 Appendix 3 Abstract of the oral presentation at the PURE conference 2015 ___________ 13 Appendix 4 Report on work done at Rothamsted Research, UK for the PURE project (Draft paper)____________________________________________________________________14 Page 2 of 33 PURE – Deliverable D10.5 1. Summary We reported the results of two-years work aimed to evaluate the effectiveness of margin manipulation using flowering mixture to enhance biological control. The experiment included complementary sampling methods of the natural enemies and of the predation service provided by it. Results suggest that with differences related to the predatory guilds, margin manipulation may enhance predation rate, especially of specialist natural enemies. Although there are potential benefits of the inclusion of brassicas in field margins, the brassica species or varieties selected should be chosen carefully, and combinations with the longest possible flowering period should be used to maximise the availability of floral resources and extend the window over which specialist pest larvae are available as prey or hosts. 2. Objectives Manipulating field margins have been suggested as a method to increase the beneficial services, especially of natural enemies, to suppress pest populations in cultivated fields. Planting flowering crops and/or flowers is the most often recommended method to achieve this, especially due to the additional alternative food provide to natural enemies (nectar, pollen), and the shelter function. We tested the effect of plant cruciferous flowering crops on the natural enemies and on predation rate to make recommendations concerning this method. 3. Deliverable procedure The project was carried out over two years in Denmark and the UK using complementary (as far as possible) experimental arrangements. 3.1 Experiments in Denmark In Flakkebjerg (Zealand, Denmark), during the field season 2013, a flowering mixture composed of two cruciferous plants (Brassica rapa var. rapa and Raphanus sativus var. oleiformis) was planted along the edges of respectively two winter wheat (Triticum aestivum), and three oil seed rape (Brassica napus) fields. Natural enemies were collected, counted, and identified to the broad taxonomic level (order or family), using directional pitfall traps (30 July - 6 August, 14-21 August, 28 August- 4 September) and vacuum sampling (2nd, 15th, 28th August). Moreover, predation rate was measured using artificial sentinel prey (30th July, 15th August, 29th August) made of plasticine as for 2014 (see below for details). Sampling took place in flowering and grassy adjacent margins of fifteen meters long each. In 2014 the same flower mix was planted along the edges of five winter wheat fields (6.7 ±3.3 ha). Each field was bordered by a natural grass strip ca. 1m wide and in the opposite side by a 50m long and 2.5m wide flowering margin, excluding one field where only the grass margin was used for logistic reasons. Only the central 15m of the margin were used for the experiments. The grass strips were selected to ensure they were distant from other flowering areas and regularly cut, to avoid additional flower resources in the control margin. Associated with each margin (edge part), a strip of crop of equal size and located 10m away from the margin (inner part) was investigated in order to compare the effect of the margin on the arthropod composition and their activity. The flowering strip was established on 10 April 2014 and started to flower on the beginning of June 2014. When the wheat was harvested at the end of July 2014, the flowering was over. Page 3 of 33 PURE – Deliverable D10.5 3.1.1. Arthropod sampling methods The arthropod composition of the natural enemy guild was determined by using two complementary sampling methods. Epigeal predators were collected using directional pitfall traps (two single pitfall traps, 500ml volume and 10cm diameter, filled with 100ml ethylene glycol 70%, connected asymmetrically by 1m long plastic barriers). This arrangement formed two funnels, causing one of the pitfalls to catch mostly arthropods moving into the field, while the other captured mostly arthropods intending to emigrate from the field. For each field, two groups of directional pitfall traps 5m distant from each other were arranged in the inner part of each plot, for a total of 40 single traps. Each trap was covered by a square cover made of galvanized iron (10×10cm), in order to reduce the by-catch. The traps were collected fortnightly on four dates in 2014 (21-28 May, 3-10 June, 18-25 June, 2-9 July). A total of 144 samples were collected by this method. Vegetation dwelling arthropods were collected using a suction device made of a converted and modified portable leaf blower (Husqvarna® 125BVx). The vacuum tube measured 85cm long and 12.5cm of diameter. The collection bag made of a fine cotton mesh (20×30cm) was held in place by a ring collar stuck between the two parts of the vacuum tube. Sampling was made by walking along a 15m transect in both the inner and edge part of the margins. Sampling occurred fortnightly on three dates in 2014 (3rd June, 16th June, and 1st July), for a total of 54 samples. Vacuum samples were stored at -20°C overnight before sorting. All the collected arthropods were identified to the order level or, in the case of beetles (Coleoptera), to family using identification keys of Choate (1999) and Unwin (1984). 3.1.2. Quantifying predation intensity Predation pressure was quantified in each margin using two methods: exclusion cages containing the grain aphids (Sitobion avenae) acting as real sentinel prey; and artificial sentinel prey made of plasticine. Exclusions cages consisted in three different types (open, partially closed and totally closed) placed in a random sequence in the inner part of the field, arranging each at 5m from the next. Cages were cylindrical and made of solid plastic (31.5cm diameter, 50cm height). The open cage was fully uncovered, the partially closed cage was covered by a plastic mesh 2x2cm size and uncovered at the bottom, and the total exclusion cage was fully covered with a muslin mesh and hence used as control. To ensure that no predators could enter the total exclusion cage, a first muslin mesh was placed on the cage and glued to the frame and a second muslin mesh was placed on the ground and ridden up to overlap with the first mesh. The open cage allowed the access both to invertebrate and small vertebrate predators, while the partially closed only to invertebrate. In each cage, a pot containing several 10cm tall winter wheat plants was infested by ten grain aphids of mixed age classes (nymph and adult), and placed to soil level (except for the total exclusion cages, where the pot was put on the bottom mesh).The fate of these aphid colonies was followed during the flowering period of the flower margin, with nondestructive counting twice a week. If a population of aphids went extinct in the total exclusion cage or in either the open or partially closed cage, the experiment was re-installed and restarted for the whole field. In total we concluded 24 experiments from 7 June to 7 July 2014. In order to determine how the provision of the biological control