Logical Reasoning

PT103 · S3 · Q14 A commercial insect trap consists

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A commercial insect trap consists of a small box containing pesticide mixed with glucose, a sweet substance known to attract insect pests.

Curious Phenomenon

Recently installed traps are far less effective than in eliminating pests than were traps installed several years ago.

Hypothesis

The reason traps in certain households decreased in effectiveness is that successive generations of insects developed a resistance to the pesticide in the traps.

Evaluate

Since the author is presenting a Curious Comparison (the more recently installed traps eliminate far fewer pests than the old ones did) and trying to explain it (the newer pests have developed resistance to the poison inside), we would think about this as we always do when an author is Explaining a Curious Fact:

- could there be some Alternate Explanation for the curious fact? maybe the newer traps are less effective because the trap manufacturer changed the glucose/poison formula. maybe the newer traps are less effective because the insects have just learned to avoid them by seeing their friends and relatives enter but never exit.

- how plausible is the Author's Explanation for the curious fact? if we were to insert some insects into these households who haven't been living with these traps for successive generations (and thus who wouldn't have been able to develop resistance), do they get killed at the higher rate like when we first installed the traps?

Goal

Since this is Weaken, we want an answer to either - suggest an Alternate Explanation for why these traps don't seem to be as effective any more, or - undermine the plausibility of the Author's Explanation that successive generations of pests have developed resistance to the pesticide

14.

Which one of the following, if true, most seriously undermines the hypothesis?

Correct
In households where the traps
Why this is right
This supplies an Alternate Explanation for why the traps are less effective. The pests haven't evolved a tolerance for the poison (pesticide) inside the trap. They've just evolved an aversion to the glucose that is supposed to be baiting them to come inside. So the real reason the traps aren't effective any more is not that the pests are eating the poison but not dying from it; it's that they aren't even going inside the traps and eating the glucose/poison combo.
Skill tested: Weaken · how this choice captures the argument's function is the move to repeat next time.
59% picked this
Even when only a few
Strengthens
This increases the plausibility of the Author's Explanation by attesting to the fact that offspring of parents who survived a bout with the pesticide have usually developed a resistance to that pesticide.
2% picked this
After eating glucose mixed with
Strengthens
This provides the classic "No Cause, No Effect" plausibility strengthener. Insects that live in houses that do not use the trap (i.e insects that have not had a chance to develop resistance over successive generations) are more vulnerable to dying from the pesticide. This makes it seem like "living in the house with these traps" is the causal difference-maker that accounts for the "less dying from these traps", which helps support the author's story.
13% picked this
After the manufacturer of the
Strengthens
This rules out the possibility that the real reason the traps are failing these days is that the manufacturer changed the formula and made it less toxic. And it strengthens the plausibility of the author's notion that the pests have developed resistance to the pesticide if we learn that even when the insects ingest a higher concentration of the poison, they're still not dying.
21% picked this
The kind of glucose used
No Impact
We don't really care whether this is natural or synthetic glucose. We would only care if they had changed the type of glucose used (because that could suggest an alternate explanation for why the traps aren't as effective now -- maybe the insects are not attracted to the new glucose).
5% picked this

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