Wild bees in the Hoeksche Waard Wilson Westdijk C.S.G. Willem van Oranje Text: Wilson Westdijk Applicant: C.S.G. Willem van Oranje Contact person applicant: Bart Lubbers Photos front page Upper: Typical landscape of the Hoeksche Waard - Rotary Hoeksche Waard Down left: Andrena rosae - Gert Huijzers ​ ​ Down right: Bombus muscorum - Gert Huijzers ​ ​ Table of contents Summary 3 Preface 3 Introduction 4 Research question 4 Hypothesis 4 Method 5 Field study 5 Literature study 5 Bee studies in the Hoeksche Waard 9 Habitats in the Hoeksche Waard 11 Origin of the Hoeksche Waard 11 Landscape and bees 12 Bees in the Hoeksche Waard 17 Recorded bee species in the Hoeksche Waard 17 Possible species in the Hoeksche Waard 22 Comparison 99 Compared to Land van Wijk en Wouden 100 Species of priority 101 Species of priority in the Hoeksche Waard 102 Threats 106 Recommendations 108 Conclusion 109 Discussion 109 Literature 111 Sources photos 112 Attachment 1: Logbook 112 2 Summary At this moment 98 bee species have been recorded in the Hoeksche Waard. 14 of these species are on the red list. 39 species, that have not been recorded yet, are likely to occur in the Hoeksche Waard. This results in 137 species, which is 41% of all species that occur in the Netherlands. The species of priority are: Andrena rosae, A. labialis, A. wilkella, Bombus ​ jonellus, B. muscorum and B. veteranus. Potential species of priority are: Andrena pilipes, A. ​ ​ ​ gravida Bombus ruderarius B. rupestris and Nomada bifasciata. ​ ​ Threats to bees are: scaling up in agriculture, eutrophication, reduction of flowers, pesticides and competition with honey bees. Recommended actions are firstly more research and second management actions aimed to increase the amount of flowers. Preface My interest in bees started with a lack of butterflies. It was a sunny day in early spring. I was making a little walk and hoping for the first butterfly. Instead of a butterfly I say a huge bumblebee. It turned out to be a queen Bombus lapidarius. I made the same walk the next ​ ​ day and found a queen Bombus pascuorum and so my interest in bees started. I soon ​ realised there was few information about bees in the Hoeksche Waard, which meant there was still a lot to discover! This resulted in this profile paper. First of all I want to thank Henk Bunjes from HWL, for helping with finding information about the Hoeksche Waard. As well as Menno Reemer and John Smit from EIS kenniscentrum, for providing information about bee studies in the Hoeksche Waard. Furthermore I want to thank Gert Huijzers, Sylvia Coolen and Jaco Visser for providing photos. 3 Introduction Bees are becoming more and more popular. More people are interested in them and care about them. And bees need to be cared for, since their populations are under pressure. More than half of the species in the Netherlands is under threat. This is getting more and more media coverage. However finding information about bees in the Hoeksche Waard is quite hard, since there is very little. Therefore the aim of this report is to give more clearance in which bee species have been recorded and which species could be recorded in the future. In addition species of priority have been selected and possible actions that could be taken to help bees are given. Research question How many bee species occur in the Hoeksche Waard compared to the whole of the Netherlands? Subquestions: ● What research has been done already concerning bees in the Hoeksche Waard? ● Which habitats are present in the Hoeksche Waard? ● Which bee species have been recorded in the Hoeksche Waard. ● Which bee species could occur in the Hoeksche waard? ● What are the species of priority for the Hoeksche Waard? ● What is threatening bees? ● What could be done to help bees? Hypothesis Few bee species and mostly common species occur in the Hoeksche Waard. I expect about 40% of the known bee species in the Netherlands could occur in the Hoeksche Waard, because ea clay areas are generally poor in biodiversity and most of the Hoeksche Waard is used for intensive agriculture. This results in a landscape poor in flowers and nesting places for bees in which more specialized bees can not survive (Peeters et al, 2012; HWL, 1999). 4 Method The method can be divided into 2 parts: a field study and a literature study. Most time was spent on the literature study, as I started this with this profile paper in September. At this time the flight period of many bee species was already over. Field study I visited most areas in the Hoeksche Waard, although bees were not always necessarily the reason for the visit. I made 163 observations divided over 29 species. Both the number of observations and the number of species will increase in the next year, as I am planning to spend more time looking for bees over the coming years. I used the book “Veldgids Bijen voor Nederland en Vlaanderen” to determine species. The observations can be found on www.hwl.waarneming.nl. I started determining bees by ​ ​ photographing them, later by picking them up by hand and eventually with a butterfly net. I spent 5 days searching specifically for Andrena rosae. This resulted in 68 specimen ​ ​ recorded in 7 areas. Literature study In order to be able to carry out more aimed searches for species, I made a list of which species could occur in the Hoeksche Waard. To determine which species could occur in the Hoeksche Waard I used a model based on points. Points were awarded if the correct habitat, flowers visited for pollen or nectar, nesting places or the correct host species for cleptoparasitic bee species were present. Bees use elements in their habitat to orientate or to demarcate their territory. Bees need pollen to feed their young and nectar to survive themselves, so the correct flowers are essential for bees to occur in an area. Flower resources are more important but nesting availability also needs to be considered. For cleptoparasitic bees flower resources are less important, but the presence of host species is the driving factor behind their distribution (Torné-Noguera et al, 2014; Peeters et al, 2012). Points will also be rewarded or subducted considering the known distribution, e.g. a bee species only occurring in the south of Limburg is not likely to occur in the Hoeksche Waard. I used three models, one of polylectic bees, one for oligolectic and monolectic bees and one for cleptoparasitic bees. 5 Polylectic bees Polylectic bees collect pollen and nectar from different unrelated plant species, making them less dependent on specific flowers. Therefore all factors are of even importance and are equal in the amount of points to be divided. Figure 1.0: Model for polylectic species Factor points Habitat Not present 0 Present 1 Common 2 Flowers visited for pollen and nectar Not present 0 Present 1 Common 2 Nesting places Not present 0 Present 1 Common 2 Distribution pattern Not likely -1 Possible 0 Likely 1 Figure 1.1: Likelihood of occurrence in the Hoeksche Waard for polylectic species Result points Very likely 7 Possible 5-6 Not likely 4 Very unlikely 0-3 6 Oligolectic and monolectic bees Oligolectic bees collect pollen from one family of plants and monolectic bees from one single plant species. This makes them highly dependable on those plants and therefore more points are awarded if those plants are present than in the model for polylectic bees. Figure 2.0: Model for oligelectic and monogelectic species. Factor points Habitat Not present 0 Present 1 Common 2 Flowers visited for pollen Not present Not possible Present 2 Common 4 Nesting places Not present 0 Present 1 Common 2 Distribution pattern Not likely -1 Possible 0 Likely 1 7 Figure 2.1: Likelihood of occurrence in the Hoeksche Waard for oligelectic and monogelectic species Result points Very likely 9 Possible 6-8 Not likely 4-5 Very unlikely 0-3 Cleptoparasitic bees Cleptoparasitic bees lay their eggs in the nest of other bees. They are generally dependent on one or a few species to lay their eggs. Therefore it is very important these species are present, because without the host species the cleptoparasitic bees can not survive. For this reason the most points in this model are awarded for the host species and less for habitat and flowers visited for nectar. Figure 3.0: Model for cleptoparasitic species Factor points Habitat Not present 0 Present 1 Common 2 Flowers visited for nectar Not present 0 Present 1 Host species Not present Not possible Present 3 Distribution pattern Not likely -1 Possible 0 Likely 1 8 Figure 3.1: Likelihood of occurrence in the Hoeksche Waard for cleptoparasitic species Result points Very likely 7 Possible 5-6 Not likely 4 Very unlikely 0-3 Bee studies in the Hoeksche Waard Bees are interesting organism to study, however difficult as well. Their behavior is what makes them interesting. Their ability to pollinate plants and create honey made them interesting to menkind. Although there is only one species that produces honey. All other species have different ways of living (Peeters et al, 2012). What makes bees so difficult to study are the facts that there are small or very similar to other species. In some cases microscopes are needed to see details of the jaws or the genitals before a determination can be made (Falk, 2015). In contrary to the well-known species groups like birds, mammals and plants, there has not been any intensive bee monitoring in the Hoeksche Waard. There have been a few studies, but no systematic research has taken place.