The Effects of Acantholycosa on Apis mellifera Feeding Behavior

Transcription

1 Jack Davis The Effects of Acantholycosa on Apis mellifera Feeding Behavior Abstract Because Apis mellifera are disappearing at a rapid rate, much research has been done regarding things like pesticides, diseases, and parasites, as these things are likely factors in the dwindling Apis mellifera population. One thing that has not received much attention though, is the effect of predators on Apis mellifera. Because of this lack of research and attention, we decided to test and see the effect of the small spider Acantholycosa on Apis mellifera feeding behavior. We did testing in the field at UCSD, to see if Apis mellifera would avoid a dish of sucrose when it had a small Acantholycosa in it. Contrary to our predictions, we found that the majority of Apis mellifera went to the dish with the spider. After performing a binomial test, we ended up with a p-value of 0.5. Because this was greater than 0.05, we accept the null hypothesis, meaning our results could have been a product of chance. Though these results were not what we expected, they could have happened for many reasons. One of these reasons could be because the Apis mellifera either did not see the spider, or, because the spider is so small, they ignored it altogether. More testing must be done before a definite conclusion can be established. Introduction The primary organism studied during these experiments was Apis mellifera (commonly known as the Western honey bee) (Swan & Papp, 1972). Apis mellifera is a small insect found in Europe, Asia, Africa and the Americas, whose primary purpose is pollination and honey production (Swan & Papp, 1972). They live in hives, and can be in colonies as large as 80,000 bees. The reason we studied this organism was in response to the emerging phenomenon refereed to as CCD (colony collapse disorder). In order to better understand Apis mellifera and why they are

2 disappearing due to CCD, we conducted experiments to see how they respond to predators, as predatory action may be a factor in CCD. In our case, we used Acantholycosa, or wolf spider (Ellis, 2010). There are many reasons that we believe this is a major problem that needs to be addressed through research and experimentation. First and foremost, Apis mellifera are disappearing at an astonishing rate, with some beekeepers reporting an annual loss of up to 80% (Wall, 2011). Not only does this cost beekeepers their livelihood, it costs the entire population as well. Bees are estimated to pollinate one-third of all food, and if bees disappear, so does that food (Univ. of Arizona). In fact, the value of bee pollination is estimated to exceed $16.6 billion (Utah County Beekeepers, 2000). It is clear from these few facts, that understanding Apis mellifera and CCD is vital. That is what we hope to accomplish by doing this experiment: better understand Apis mellifera, and more specifically, the change in their feeding behavior when introduced to the predator Acantholycosa. From the research we have done, we predict that the Apis mellifera will avoid the dish with the Acantholycosa on it. Method Prior to the experiment, we will begin training the Apis mellifera by doing the following. We will set up a tripod 0.5 meters away from the Apis mellifera hive, and place one, white, 3.75 Petri dish on the tripod. One, 1.75 blue Petri dish (bottom of dish only) will be placed inside the 3.75 dish. The smaller dish will contain a 2.5 molar sucrose solution. Once this is all set up (see Fig. 1, experimental setup), we will allow the bees to come to the sucrose Petri dish. Once 7-8 Apis mellifera are there, we will move the tripod and the dishes 0.5 meters further from the hive, and will continue to allow the bees to come. We will continue this, moving the tripod further and further away from the hive until we have moved the tripod to a location 2.5 meters from the hive. Every Apis mellifera that comes to the dish will be marked on the abdomen with a dot of white paint, using a small brush.

3 After the Apis mellifera have been trained, we will begin our experiment. The tripod will be placed 2.5 meters away from the hive, and two, 3.75 Petri dishes will be placed on the tripod (white dishes). Two smaller Petri dishes (1.75 ), that have been painted blue, will be placed inside the larger dishes. Both of these smaller dishes will contain a 2.5 Molar sucrose solution. A wolf spider (Acantholycosa) will be placed into one of the larger Petri dishes, which will have a piece of mesh taped to the top, in order to prevent the spider from escaping. We will allow the Apis Fig. 1 shows the set up of our experiment. mellifera to come to the dishes for 15 minutes (we will switch the position of the dishes every 2.5 minutes). We will record the number of Apis mellifera that come to each Petri dish in our notebooks and will also record how the Apis mellifera react to the Acantholycosa. After we have finally completed our experiment, and gathered our data, we will conduct a binomial test to calculate the P value associated with our results. Results Number of Bees Dish Landed Dish With No Spider 5 Dish With Small Spider 6 Total 11 Table 1 shows the number of bees that landed on each type of dish; one that had a small spider in it, and one that did not have a small spider in it. From the results shown in Table 1, you can see that 5 bees landed on the dish that did not contain a spider, while 6 bees landed on the dish that did contain the spider, for a total of 11 bees. From this data, and by using a binomial test, we calculated a P value of 0.5, or 50%. Because this value is greater than 0.05, we accept the null hypothesis. Conclusion

4 Our hypothesis was that bees would avoid the dish with the small wolf spider in it. We did not know how the bee would recognize the spider, but we hypothesized that it would avoid it nonetheless. To our surprise, the results of our experiment (Tab. 1) completely contradict our hypothesis. Not only did bees not avoid the dish with the predator, they actually went to that dish more than the dish with no spider. We believe this could have happened for multiple reasons. For one, the spider was in the corner, partially hidden from sight, and might have been completely missed by the bees. This would explain why they did not avoid that dish. Another explanation though, could be that the bees did not view such a small spider as a threat, and therefore did not avoid it. Unfortunately, no other group tested with a small spider, and so we have no other data to compare to our own. More trials and experimentation should be conducted before any conclusions about why the bees did not avoid the dish are made. Works Cited "The Case of the Disappearing Bees." Discovery News. Web. 14 Oct < "Colony Collapse Disorder." University of Florida. Web. 14 Oct <

5 "Honey Bee Pollination." University of Arizona. Web. 14 Oct < "Honey Bees." Texas A&M University. Web. 14 Oct < "The Value of Honey Bees as Pollinators of US Crops in 2000." Utah County Beekeepers. Web. 14 Oct < 20Honey%20Bees%20as%20Pollinators%20-%202000%20Report.pdf>.