Plant-Insect-Interactions: Ent/Bot/Zool 473 February 15, 2006
Name: ______
1. (10 pts) Answer EITHER a or b
a) There are many instances in the literature where an observation is made that environmentally stressful, e.g., drought, conditions lead to increased plant damage by an insect. What additional information would you need in order to prove this stress reduces plant resistance to this insect? What other factors could account for this trend? Which author from your assigned readings proposed a mechanism between environmental stress and increased insect populations, and what was the basis of the hypothesis?
b) Describe and give examples of how knowing the physical properties of a chemical can be used to suggest what biological effects it might have. Describe how an understanding of the spatial and temporal distribution of a chemical may suggest whether it plays a defensive role.
2. (10 pts) Describe two means by which plants prevent autotoxicity. Describe how autotoxicity can be used by plants as a component of defense.
3. (5 pts) If you know a chemical is a pheromone, how could you determine if it is also a kairomone?
4. (10 pts) What are the two major hormones involved in insect development? What function does each play, and what is the major chemical class to which it belongs.
5. (10 pts) What are some means by which insects use plants to improve their likelihood of attracting mates?
6. (15 pts) Identify one group of compounds or compound FOR ANY 5 of the following modes of action
a. Inhibits digestion ______
b. Inhibits endocrine-based development ______
c. Mimics alarm pheromones ______
d. Opens Na channels ______
e. Postsynaptic inhibitor ______
f. Interferes with transcription ______
g. Increases susceptibility to pathogens ______
h. Agglutinate erythrocytes ______
i. Inhibit feeding ______
7. (10 pts) For ANY 1 of the groups in question 6, describe its chemical structure, distribution, and plant function other than defense against insects
8. (10 pts) Name one order of insects in which the overwhelming majority of species are herbivores. Describe whether its mouthparts are chewing or sucking, and its development is hemi- or holo- metabolous.
9. (5 pts) What order of insects contains the most parasitoids of other insects?
10. (15 pts) What is a trichome? How do they protect plants from insects? Are they widespread or rare? Is their protection from insects specific or broad? What benefit other than protection from herbivores might they confer? What negative effects might they have on a plant?