Category: Expertise

Calculating Flying Insect Biodiversity Using Simpson’s Diversity Index

Content standards

1. Ecosystem Structure (biological populations and communities, ecological niches, species diversity) 
   C. Ecosystem Diversity (biodiversity, natural selection, ecosystem services) 

Biodiversity is a hot topic. In the wild, habitats are shrinking and species are becoming extinct—lost forever—some without humans even discovering them. Biodiversity is also an issue closer to home. Planting large fields of a single genotype crop (e.g., corn or wheat) can make food sources vulnerable if that genotype becomes susceptible to a new pest or drought. An entire crop can be lost. In contrast, wild populations are more genetically diverse, so some individuals usually survive adverse conditions. 

When studying the biodiversity of a community, a simple survey of the number of different species (species richness) in an area seemingly would give a clear picture of the diversity. As the following example illustrates, a calculation of the species richness alone doesn’t give that clear picture. It’s not until the distribution of those species (also called species evenness) is added to the calculation that the biodiversity of a community is more accurately portrayed. 

Objectives:

• Calculate diversity values for sampled habitats, using 2 indices—species richness and Simpson’s Index
• Understand the differences between various ways of measuring and defining biodiversity

Time requirement

Sticky trap preparation and installation      30 min
Insect trapping                                        At least 1 hr (can leave traps in place overnight)
Insect collection                                      30 min
Analysis of data                                      30 min

Materials

• 100 Sticky Traps
• 4 Hole Punches
• 4 Permanent Markers
• 100 Paper Clips
• 4 Rolls of String
• 8 to 16 Hand Lenses

Safety:

Use caution when collecting living samples since they can include harmful organisms. 

Preparation (teacher)

1. Prepare 4 sets of material that each include 25 sticky traps, a hole punch, a permanent marker, 25 paper clips, and a roll of string.
2. Examine your campus and identify areas that seem appropriate for collecting flying insects, e.g., along a chain link fence, off a tree branch, or between 2 fixed objects (where it’s possible to tie string tightly to each object). Compile a list of areas suitable for collection. Ultimately, allow groups to pick their locations from the list.
3. Divide your class into 4 groups and assign each group a letter.

Note: This activity is best done when there isn’t a lot of air moving. Wind can dislodge sticky traps. 

Procedure:

1. Punch a hole in the top of each sticky trap.
2. Using a permanent marker, label each trap with your group letter and number traps from 1 to 25.
3. Go outside.
4. As a group, decide which designated flying insect habitat to study. Consider how you will use the paper clips and string to ensure that all 25 sticky traps are in a single habitat. Secure the traps to branches, fences, or between 2 immovable objects (using tightly tied string). Best results occur 3 to 5 ft off the ground. Note: Be sure the traps are in a single habitat and are set at the same general height and in the same general conditions. Setting traps in multiple conditions will skew the results.
5. After setting each trap, remove the wax paper from the sticky trap.
6. Return to the classroom.
   Note: Wait at least 1 hour or, if necessary, until the next class period.
7. Go outside, collect the sticky traps, and return to class.
8. Place your group’s sticky traps in numerical order and use a hand lens to examine the specimens.
9. As a class, decide on consistent morphotype name designations (e.g., black spotted, red dotted, small black, big brown, or large round) for samples. Then enter the chosen names for morphotypes into the table (see Figure 1 for an example). This allows for combining data accurately later in the activity.
10. Divide the 4 groups of students into pairs. Then divide the sticky traps evenly among the pairs of students. One of the student pair identifies the insects and, using the agreed-upon names for morphotypes, the other student counts and records the number of each morphotype in the Sample Data Table (see Figure 2).
11. After all of the data from each student pair is entered into the data table, calculate the species richness and Simpson’s Diversity Index for each habitat.

Figure 1 Example Data Table of Morphotypes (using class-designated names)

 

Morphotype #	Morphotype Description	number	number/total	(number/total)^2
1	spider	2	0.01142857143	0.0001306122449
2	winged black ants	6	0.03428571429	0.001175510204
3	bee	1	0.005714285714	0.00003265306122
4	horsefly	16	0.09142857143	0.008359183673
5	big blue wasp	0	0	0
6	snail	2	0.01142857143	0.0001306122449
7	green iridescent fly	5	0.02857142857	0.0008163265306
8	mosquito	31	0.1771428571	0.03137959184
9	small fly (fruit flies, tiny black flies)	94	0.5371428571	0.288522449
10	moth	3	0.01714285714	0.000293877551
11	wingless ants (tree ants, red ants)	0	0	0
12	small hoppers	12	0.06857142857	0.004702040816
13	cricket	0	0	0
14	beetle	3	0.01714285714	0.000293877551
15	Water strider	0	0	0
16	Worm	0	0	0
	Total	175	1	0.3358367347
			Simpson = 1 –	0.6641632653
			Simpson	0.335836735

 

 

Figure 2 Sample Data Table

Habitat Types	Simpson (Species Richness) Total: 16 species	Simpson’s Diversity Index
Zone A : Behind Senior Housing	11	0.2790007048
Zone B : King Seven Pond	10	0.6347107438
Zone C : Mango Trees	11	0.5580145239
Zone D : Garden	12	0.6641632653

Questions

1. Compare the species richness and diversities of the 4 different habitats studied. Which habitat was more diverse in terms of richness and evenness? What evidence do you have?
   1. According to the Species Richness graph Zone D has the most diverse in terms of species richness and evenness because of all the habitat Zone D has the most number of species (12 species). Moreover, according to the Diversity Index Zone D has the most.

2. How does the diversity of each habitat compare using the Simpson’s Diversity Index as opposed to just species richness? Which is more accurate?
   1. The diversity of each habitat compare using the Simpson’s Diversity Index as opposed to just species richness is that the Simpson’s Diversity Index is more distance from each other where is the species richness is more clump together. I think Simpson’s Diversity Index is more accurate because Simpson’s Diversity Index is a measure of diversity which takes into account both richness and evenness.
3. Describe your group’s habitat in terms of its biotic and abiotic conditions. How did these conditions influence the species richness and diversity of insects in that habitat? Do the types of insect found “fit” that habitat? Why or why not
   1. My team we are measuring the biodiversity of flying insect in the garden area. There are many abiotic conditions such as soil, water, dead wood, and composed; moreover, there are also many biotic conditions such as grasses, trees, and small plants. I think the condition that influence most about the species richness and diversity of insects in that habitat is the composed where we can see in my team there are many fruit-flies were trapped. I think those type of insects in that habitat  is fitted because the fruit-flies especially attracted to the composed.
4. How does your habitat compare to other habitats around campus? What factors could have led to differences in diversity between the habitats?
   1. I think my habitat is similar to the other habitats around the campus, but one factors that could have led to differences in diversity between the habitats is that the composed and small bushes where it attracted a lot of different kinds of insect especially different types of flies and mosquitoes.
5. Was your community of insects primarily composed of primary consumers, secondary consumers, or a combination of both? What inferences can you make about the rest of the community in this habitat?
   1. My community of insects primarily composed of primary consumers, and some mix of both; most of the primary consumers were organism that eat fruit and leaves, such as fruit-flies and horse-flies, as well ants. Moreover, the insect such as mosquitos and spider there are secondary consumers where they prey upon other small insects. I think there also a lot of decomposer as well, because the habitat is wet as well as human influence where we, Liger’s students, making composed there.
6. Was your data accurate? Why or why not? Could this methodology have been improved upon? What other factors could have been measured to account for species diversity?
   1. I think my data isn’t accurate due to many influences one of which is rain. Before the experiment, I think that we will got a lot of horse-flies because of the composed but then it turns out that there are less of horse-flies. I think the methodology should be change where we try to choose different places in Liger or outside where the habitats is much different from each other moreover try to have less influences on the habitat that causes the result to be bias. I think the other factors could have been measured to account for species diversity are the area of the habitat and the influences in the habitats.
7. Why is it important to take into account both species richness AND evenness when assessing community diversity?
   1. It is important to take into account both species richness and evenness when assessing community diversity because the species richness is contributed to increase in biodiversity also which is an important aspect biodiversity; moreover the species evenness measure the ratio between each organisms where is if we have species evenness this show that the community diversity is healthy.
8. Why do you think biologists assess species diversity of a community? What does it tell you about the health of the ecosystem?
   1. I think the biologists assess species diversity of a community because they want to know about the species richness as well as the species evenness of an ecosystem. As there more and more species richness and those species are even up on each other the ecosystem is healthy.
      
9. Which of the following habitats is more diverse: A habitat including 10 species, each represented by 2 individuals? Or a habitat including 10 species, 1 of which is represented by 85 individuals and the remaining 9 species represented by 1 individual each? Explain your answer.
   1. The habitat that include 10 species, each represented by 2 individuals is more diverse. Because diversity is measure how rich the species in a habitat and evenness of species in the habitat. Both habitats has the same number of species but the first habitat the number of species is even but the second habitat is unbalance between the species evenness so it makes the first habitat is more diverse than the second one.