The new technologies and products offered by the private industry in agriculture constitute a huge amount of economic investment that companies try to protect in order to ensure profit and competitiveness. However, a high level of secrecy in the management of the information on new crops is considered by researchers as counterproductive in obtaining reliable knowledge (i.e., independent) on the products, which ultimately hinders a more expedite acceptance from the public in general (growers and consumers). Intellectual property has become a shield that protects the interests of the industry in such a way that it could become a barrier that does not allow them to expose their products to the public scrutiny and ultimately to the free market. In my opinion, sooner or later the industry will come to recognize that any attempt to take unfair advantage of confidentiality in business information (i.e., to hide bad features before the product is commercialized) could represent a future liability of unknown consequences.
Who really is in control? With regards to how products are regulated, what changes would you make if any?
It is totally clear that the industry is in control, as mentioned by Christian Krupke “they are completely driving the bus”. Unfortunately this is how the system works so far, the companies exert a great pressure in the political system and ultimately they set the rules in order to protect their interests. However, the regulation on products directed toward human consumption should not just have more restricted regulations, but to be public-oriented; that is, to be approved under a crystalline process in which the academia and the general public have total access and even participation, so we can, as a society, participate in the construction of our food security. Any kind of regulation or policy that interrupts an open discussion on “what we are eating” constitutes a delay in the normal flow of knowledge, acceptance, and utilization of such new technologies.
Are researchers "blowing this out of proportion"? Should growers be provided with disclaimers when companies approach them with performance data (i.e., whether product was tested with competitor lines)? When should biotechnology be used on the farm?
I tend to believe that not only growers should enjoy the right to be informed about what they are putting in the field, but all people involved (i.e., consumers) should have enough information on the products they are purchasing. As mentioned before, only through an open and frank discussion new technologies will stop being used as cartoons by critics, and they will start being focus of serious debate and acceptance processes.
As any other technology, biotechnology should be used in the field when it represents an advantage over the conventional technique (i.e., transformed varieties with drought tolerance, pest resistance, higher yield, etc.), and does not represent a threat to the environment and the consumers.
Can such products lead to increased food security? You're not limited to these questions, but I do encourage you to expand on your answers for full credit.
Part 1.
Why does the functional response reach a plateau?
The functional response reaches a plateau because the consumption of prey is affected by the level of satiation of the predator. A well fed predator would either attack a lower number of preys or even it would ignore them. The starvation level of the predator would have the opposite effect of the level of satiation.
What variable determines the level of the plateau? What other factors could affect the total number of aphids that are attacked within a 24 hr period of time?
As mentioned previously predator satiation determines the level of the plateau. However, other factors can affect the level of the plateau such as prey density, predator’s searching efficiency, and predator’s handling time. Prey density constitutes the probability that a predator has to encounter the prey and secondly the possibility of achieving satiation, low prey densities would represent low probabilities of encounters and thereby it would represent a delay in satiation. On the other hand, high prey densities would accelerate the process of satiation. Other important factor is predator’s searching efficiency; this factor interacts with prey density and it has to do with the opportunities that a predator may have to encounter the prey related to its particular predatory skills and adaptations. A well adapted predator should exhibit high searching efficiency at attacking its favorite prey, in that sense the level of satiation in a well adapted predator could be achieved faster if the prey exhibit high density than if the prey is in low density. Another important factor that could affect the level of satiation, and thereby the level of the plateau, is the handling time, how long the predator takes to process and consume a specific kind of prey. As mentioned in the lab hand out, handling time per prey item is specific to the nature of the prey and it is the same regardless the number of prey available. However, the total handling time could be small if prey density is low (lower prey items to handle), and it could be large if prey density is high (more items to handle). Handling time can determine the level of the plateau if a predator exhibits either short or long handling time per prey item, that is a predator with a long handling time would delay satiation, even under high levels of prey density, because it would spent much of its available time in handling the prey.
What was the average handling time for the feeding events that you observed (be sure to include your raw data as well as the average (or mean) and standard error)? How does this compare to the table in your lab handout? Also, describe what you classify as an “event” (specific start/stop behaviors, etc.) and any other things you observed along the way.
Table 1. individual of H. axyrids preying on soybean aphids during three separated observations.
Observation
(each one of 2 minutes)*
Aphids consumed
(events)
Handling time per event (seconds)
Grooming time (seconds)
1ST
3
11.6
30
2ND
1
20.0
40
3RD
1
40.0
40
Mean
1.6
23.8
36.6
Stdv
1.1
14.6
5.7
SE
0.6
8.4
3.3
* The beetle was separated from the aphids during 2 minutes after each observation
According to my observations the individual consumed in averaged 1.6 aphids per 2 minutes of observation (=1.6 aphids/2 minutes), it took almost 23.8 seconds/event in handling time, whereas it spent 36.6 seconds/2 minutes in grooming; the rest of the time the insect was observed resting (that could constitute about 50% of the time, ~1 minute). If we consider the table 3 of the lab handout, a female would spent around 0.85 seconds/2 minutes in total handing time (0.17 hrs per every 24 hrs of observation), in my case the beetle spent 23.8 seconds in handling time per event, which means 38 seconds/2 minutes in total handling time (1.6 events/2 minutes * 23.8 seconds Ht/event). This is a very large value in comparison to than in table 3.
It is important to note that between the 1st observation and the 3rd, the predator showed a decline in the number of events and an increase in the handling time. In this case the beetle exhibited lower levels of handling time and greater number of aphids consumed in the 1st observation due probably to a certain level of starvation that was somehow overcome with few prey items; then the predator increased handling time and reduced the number of aphids consumed during the third observation.
Aside from handling prey, how did the predator(s) you observed spend the rest of their time? Why are these behaviors important to the ladybeetle?
I observed the beetle eating an exuviae and a dead aphid. It seems that the mechanism of detection of prey does not involve the recognition on the conditions of the prey. Besides, in the last observation (3rd) the beetle was taking longer to eat the last prey (40 seconds) and it was not chewing but just maintaining the aphid in its mouth. It seems that resting between events is a very important behavior for this animal (around half of the time) followed by grooming, where the insect spent almost 40 seconds out of the 120 allowed. I imagine that resting has to do with the level of starvation of the animal and secondly, with its sex; in my case the observations were done using a male and it is possible to suggest that a female may experience a different level of satiation/starvation dynamics in virtue of the energy they invest in reproduction. In relation to the grooming behavior, I speculate this behavior is important to maintaining clean all mouthparts that are in contact with prey fluids and others, so insects can avoid providing sporulation medium for bacteria and fungi.
Discuss your experience with this exercise. What surprised you about the predator behaviors that you observed? Does this tell you anything about the predictability of biocontrol under field conditions?
It was surprising to me to see how much of the time was spent in grooming and resting. In my personal observations with this species, and particularly observing the females, I have found that they actively consume the prey and one can see them eating in a high frequency of their times. However, in my observations I have not measured time at consuming the prey, handling time and others, so it is possible they just do not behave as I thought.
The predictability of using biocontrol under field conditions is being a great question in relation to this specific group of predators. Even though the first and greatest example of classical biological control was done using a coccidophagous ladybeetle, the history has not been plenty of successful examples when talking about aphidophagpus ladybeetles. In fact, most of the studies in functional response of different species of aphidophagous ladybeetles have found little, if any, effect of the predator’s action on the population dynamics of the prey
(See figure 1); in contrast, some authors have proposed that a numerical response could be more important at analyzing the effect of a predatory ladybeetle in aphid’s population, which is the quantity, quality and distribution of the offspring. In this regard, Kindlman and Dixon (2002) pointed out that “for adults, the finding of oviposition sites is assumed to be more important than the functional response to prey”.
Part 2.
Who was in your group? What was your responsibility?
In my group I share activities with Amy Willmot, Deane Kraus and Matthew Sellner. I was in charge of recording the times.
On average, how much time did they spend on the behaviors that you recorded (give standard errors)?
Table 2. Observation of time spent in walking, grooming, resting and feeding in two H. axyridis individuals.
Observation
Seconds spent
Two different beetles
Walking
Grooming
Resting
1st
133
118
49
2nd
121
161
18
Mean
127.0
139.5
33.5
Stdv
8.5
30.4
21.9
SE
6.0
21.5
15.5
On average the beetles spent 127 seconds walking (42% of time allowed), 139.5 seconds grooming (46.5% of time allowed), and 33.5 seconds in Resting (11% of time allowed). The two major activities in which the beetles engaged were walking and grooming, whereas there was not any observation of feeding.
Describe the path that each predator took (straight lines, turning, random, directional, etc.)? Was either of the ladybeetles successful in finding the patch of aphids? Was this surprising to you? Why or why not?
According to the assessment of the movement of the beetles on the glass top of the arena provided (Figure 2), the predators were rather following sort of straight lines with random shifts in direction. Unfortunately none of our beetles was able to reach the aphids, so there was no any record of time feeding. This comes as a surprise because I was expecting more efficiency of the predatory behavior. However, it is important to consider that we just allowed them five minutes of observation and maybe they could require a larger period of observation or/and a different sort of arena. In this regard Obata (1986) studying the mechanisms of prey finding of Harmonia axyridis found that the adults were more attracted to the odor of plant leaves, “regardless of whether or not these were aphid-infested”. So maybe the problems of the beetles at reaching the prey was related to the small leaf area provided in relation to the whole arena (figure 2), and in field conditions they may be guided more by the position of plants in the landscape and once in the plants guided by the smell of the leaves.
References:
Kindlman and Dixon (2002) Insect predator-prey dynamics and the biological
control of aphids by ladybirds. Available online at: http://www.bugwood.org/arthropod/day1/kindlmann.pdf
Obata, S. 1986. Mechanisms of prey finding in the aphidophagous ladybird beetle, Harmonia axyridis (Col.: Coccinellidae). Entomophaga 31(3). P. 303-311
