Swallowtails workshop, Part 2: Paper 1. Some new notes on breeding the Carrot family (Umbelliferae)-feeding Swallowtails on an Artificial diet.

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2 Swallowtails workshop, Part 2: Paper 1. Some new notes on breeding the Carrot family (Umbelliferae)-feeding Swallowtails on an Artificial diet. : July A Black Swallowtail on Verbena. This is an easy Swallowtail species to breed, and an ideal option for experimenting by feeding the larvae on Artificial diet. They are also suitable for hybridization experiments. Some thoughts from our previous Workshop (Part 1) discussions. During the discussions in Swallowtail Workshop 1, it became evident that some breeders were experiencing problems when trying to provide hostplants for feeding Swallowtail larvae that eat the Carrot family (Umbelliferae). Based on this feedback, I felt that this was an important subject and it was useful to get this information out to you now. I have therefore rearranged my intended topic headings/papers, so that I am able to include this new topic and still retain all of the topics that I originally intended to cover in this workshop. The information in this paper is aimed at those of you who may be struggling to breed the carrot-feeding group of Swallowtails, in particular where the most suitable host-plants either do not grow well in your own local climate or are not readily available to you. A secondary reason is that, having bred many larvae, you may well find that you are running out of host-plant to feed them on. It is a case of feeding the larvae or losing them all! Page 1

3 Background to the experiment. One problem discussed in the first workshop was that the best host-plants from this family do not grow well in all places, and several different options were discussed. I have always considered rue (Ruta graveolens) to be a great host-plant, especially as it does not wilt as easily as most of the alternatives. By comparison, cut fennel (Foeniculum vulgare) will start to wilt in minutes. However, I found that the female Swallowtails laid more freely on fennel than on Rue. The only real option for continued success with breeding this group of Swallowtails was through considerable, well-organized preparation, with a lot of time and effort spent in growing enough host-plants to satisfy the larvae. This set me thinking about an experience I had in the past, where I had eggs of a Sphinx-moth and no host-plant available at all to feed the voracious larvae. I had just returned to the UK from Argentina after the Christmas holidays, and I had managed to obtain some eggs of an interesting Sphinx-moth. I knew the larvae would feed on plants from the potato family (Solanum), as I had managed to get the female to lay on these plants in Argentina. My plan was to rear the larvae on potato vine (Solanum jasminoides) after returning to the UK. I had left Argentina (southern hemisphere) in midsummer, but in northern-hemisphere UK it was, of course, mid-winter. At this time of year in the UK there are very few food plant options available, and potatoes in particular are not in-season. With this in mind, my plan was instead to use the potato vine, which keeps its leaves in winter. Unfortunately I arrived home after a particularly cold spell of weather that killed all of the potato vine leaves. With the larvae due to hatch, I was desperate to find an alternative. I went to the local supermarket and bought some potatoes. I took these home, sliced them, and just added the Sphinx moth larvae hatchlings onto the slices. I was not confident of success, because the actual potato tuber, which grows underground, is not something that these larvae would eat in the wild. The set-up that I used consisted of plastic boxes with large holes cut in the lids. The holes were then covered with netting stuck into place. While I don t usually like to use plastic boxes to breed my larvae, here I really had no option. When I have to use this method, I always cut the holes to allow a good airflow. One further adaptation is that I then tape a strip of kitchen Cling Film to one end of the netting on the top. This allows me to adjust the airflow within the box by moving the cling film over the netting or back as conditions inside the box require. The trick is to achieve a balance between allowing adequate airflow for the larvae and not allowing the host-plant (or potato slices in this case!) to dry out too rapidly. Page 2

4 The bottom of the box was lined with kitchen paper to trap any excess moisture that the potato slices produced. I started out with small boxes and increased the size of the boxes as the larvae grew and developed. The experiment was a success! I not only managed to produce extremely large, healthy pupae, but my losses were fairly minimal. One interesting aspect is that the frass produced by the larvae was bright orange, which was due to the fact that there is no chlorophyll in potato tubers, just carotene. Both carotene and chlorophyll are passed out in natural conditions undigested, and it is the chlorophyll that gives normal frass its dark colour. The experiment to date. After the end of the first Workshop, I contacted Connie Hodsdon from Florida, to ask her if she would conduct some experiments breeding the Black Swallowtail (P. polyxenes) and feeding the larvae on the cheapest cut supermarket carrots she could find. Unlike plants from a nursery, your own Food Standard Agencies will always ensure that food for human consumption is free from pesticides. (I am very grateful to Connie for all the work she did with this experiment, especially as it was at a time when her own business was producing 1,000 s of pupae a week and she was working all hours of the day to keep her business flowing.) Like all experiments, there needs to be some tweaking to try and get the best results. However, I thought it important to get this information out to you, for those of you who would like to continue the experiment. The main conclusion is that the larvae do eat cut carrots. However, the balance between the carrots drying out and keeping the larvae healthy still needs to be worked out. It is important to realise that, if we never try these experiments, we never progress! You may also like to consider trying any alternatives that may be available in your supermarket. For example, parsnips are readily available in most areas, and less obvious foods such as Florence fennel bulbs are becoming increasingly available in many of the larger supermarkets. Page 3

5 Florence fennel is increasingly available from supermarkets. I am certain that the larvae will eat the sliced bulb as well as the green sprouts! One point that may give you extra confidence in this experiment is that the Swallowtail larvae will transfer from normal host-plants to the cut carrot slices and vice-versa. Any of you that have tried using normal Artificial Diet for other species such as Painted Ladies, will know that once larvae have started feeding on natural host-plants it is very difficult to get them to take A.D.! Linda Rogers has now started some experiments of her own, having received start-up stock from Connie. The challenge is there for you all to try, and be certain that you are breaking new ground in making this work. I do hope our discussion on this subject here in the Workshop will be lively and interesting. The following pages show some of Connie s photos, which will give you a general view of how she approached this experiment. Page 4

6 A mixture of different early instars feeding on carrot slices. Some slices have been strung on Barbecue skewers. Page 5

7 A mixture of older larvae feeding on a combination of cut host-plant and carrot slices. Page 6

8 I do hope that this paper has stimulated your interest in trying this experiment for yourself. This may, in the end, prove not to be a practical way forward, but it is fun to try! : July Swallowtail Workshop Part 2. Paper 1a. Some new notes on breeding the Carrot family (Umbelliferae)-feeding Swallowtails on an Artificial diet. Page 7