Cooperation and conflict: How insects interact with each other and their environment

Transcription

1 Cooperation and conflict: How insects interact with each other and their environment

2 Overview Five examples of cooperation and conflict in insects (and its consequences) Cooperation requires communication: a simple and highly reliable experiment with termites.

3 Cooperation and conflict: How insects interact with each other and their environment Relevant Standards: Describe specific relationships (predator/prey, consumer/producer or parasite/host) between organisms and determine whether these relationships are competitive or mutually beneficial Observe and classify common Indiana organisms as producers, consumers, decomposers, predator and prey based on their relationships and interactions with other organisms in their ecosystem Design an investigation to explore how organisms meet some of their needs by responding to stimuli from their environment.

4 5 CASE STUDIES IN COOPERATION AND CONFLICT IN INSECTS

5 Cooperation and conflict: examples Example 1: Nicrophorus, burying beetles utilize carcasses as a food source one pair locates a carcass (mouse, rat, snake, small rabbit, frog, toad, bird etc) move carcass to suitable location (how?)

6 Cooperation and conflict: examples Example: Nicrophorus, continued remove fur and feathers embalm carcass using anal secretion to prevent rotting shape carcass into ball ( cake ) and bury carcass underground then female lays eggs inside carcass completely dependent larvae emerge; must be fed at least over the first 2 instars males assist throughout, but abandon female once larvae are past 3 rd instar (but only in the summer, never in the fall; why?)

7 Cooperation and conflict: examples Example: Nicrophorus, continued as an aside: females do not know the exact size of their carcass at the time of oviposition often females will lay more eggs than the carcass can ultimately support she knows the number of larvae she can probably rear by the time they are 2 nd instar what does she do with the surplus larvae??

8 5 CASE STUDIES IN COOPERATION AND CONFLICT IN INSECTS

9 Cooperation and conflict: examples Example 2: Onthophagus taurus, dung beetle females lay eggs inside tunnels underneath dung pads males defend tunnels by engaging rival males in combat using horns as weapons small males do not develop horns, do not fight, and instead engage in non-aggressive sneaking behavior to access females

10 b) hornless males sneak (after Moczek 2004) a) horned males fight Drawing by Barrett Klein

11 Cooperation and conflict: examples horn length (mm) horn length body size (mm) female

12 Cooperation and conflict: examples NOTE: We will revisit dung beetles tomorrow to explore how other species use their horns, whether horns might have alternate uses, and how we might test different hypotheses regarding the origin and uses of horns.

13 5 CASE STUDIES IN COOPERATION AND CONFLICT IN INSECTS

14 Competition between males, and between males and females, and continues beyond mating and insemination Remember insect reproductive organs:

15 The aedeagus heavily sclerotized, solid tube anchors male genitalia inside female genitalia often with hooks and various projections sometimes with puncturing devices (why?)

16 The aedeagus not only helps deliver sperm but also functions in male-male competition

17 Competition between males, and between males and females, and continues beyond mating and insemination The female side: at least some female insects are capable of discriminating among sperm from different males mechanisms include: - differential ejection of sperm, - withholding of sperm in spermatheca cryptic female choice probably far more widespread than currently understood

18 5 CASE STUDIES IN COOPERATION AND CONFLICT IN INSECTS

19 Cooperation and conflict: Example 4: Honey bees, Apis mellifera Background: honey bees rely exclusively on pollen and nectar as food resources individual forager bees identify forage sites, then return to nest and return with additional nest mates when initial forager is prevented from returning nest mates still appear quickly at the new forage site Conclusion: somehow information is exchanged in the hive that allows nest mates to locate new forage site

20 Cooperation and conflict: Example 4: Honey bees, Apis mellifera Background: we now know that bees use the waggle dance to communicate: (a) quality of forage site (a) distance away from nest site (a) direction relative to current position of the sun

21 Cooperation and conflict: Example 4: Honey bees, Apis mellifera Components of the waggle dance: (a) dance consits of figure-8 type dance with; bees buzz their wings and waggle abdomen during straight part (b) intensity of dance (rounds/time) and intensity of buzzing on straight part indicate quality of forage site (c) length of straight part indicates distance away from hive (d) angle and direction of straight part relative to gravity indicate angle and direction of forage site relative to the sun when viewed from the hive

22 Cooperation and conflict: Example 4: Honey bees, Apis mellifera Communicating direction of forage site relative to the sun

23

24

25

26 Cooperation and conflict: Example 4: Honey bees, Apis mellifera How precise is it?

27 Dance language of honey bees But then: a simple experiment with an unusual outcome (Lindauer 1960)

28 Dance language of honey bees predicted observed

29 Overview Four examples of cooperation and conflict in insects (and its consequences) Cooperation requires communication: a simple and highly reliable experiment with termites.

30 What you need A cheap ball pen, blue A piece of paper, clean A local termite, alive

31 What you should do Using the blue pen draw a circle on the paper Carefully release the termite in the center of the circle Carefully watch the termites behavior

32 The idea behind this exercise The termite will soon do something that will make you think It does the same to students, school kids, anyone who sees this for the first time; you can t help it If provides a wonderful opportunity to introduce the scientific method, generate hypotheses, and go test them, which is what we will do now!

33 Your job! get to know your termite, what is it doing? as a table, discuss alternative hypotheses that explain your observations what would your hypotheses predict, and how can you test these predictions? then test them share your observations draw conclusions; is your hypothesis supported? why or why not?

34 Observation: Termites follow the ink Question: How do they know where the line is? Hypothesis Prediction Test Result Conclusion