Question

Please explain the following questions in detail:

1. The introduction of gall flies to control invasive knapweed in montana permitted an increase in the numbers of deer mice. Apart from an increase in hantavirus in the area, what other effects might this have on the local community.

2. Explain how you might set a field experiment to determine whether insect pests are affecting crop yields. Be careful to include appropriate treatments and controls.

Answer 1

1. Gall flies are one class of endophytic herbivores. They force their host plants to produce tumor-like growths that provide the insects with food and shelter at the expense of the host plant. Because the killing action of natural enemies can limit the damage herbivores inflict upon host plants, such indirect defenses can benefit plant reproduction, providing plants that possess such traits with a fitness advantage. Indirect defenses can be induced by the larvae of Gall flies. They induce changes in the volatile emissions from its host plant, and these altered volatiles attract natural enemies and serve as mate location cues for the gall flies.

2. In controlled crop field units, different number of insect pests have to be released in the ascending order of number. One unit of crop field has to be kept free from insect pests as control.
By measuring the final produce of each crop field the effect of insect pests can be assessed.