有些蟑螂知道避免食進有毒藥的餌

Last month the Yomiuri News on-line reported the following

「甘くないぞ」…ゴキブリ、味覚変化でワナ回避

【ワシントン＝中島達雄】甘い物が好きなはずのチャバネゴキブリに、甘みを苦いと感じて食べないタイプがいると、米ノースカロライナ州立大の勝又綾子主任研究員らが米科学誌サイエンスに発表した。

　駆除剤による絶滅を逃れるための生存戦略とみられ、こうしたゴキブリの対策には、駆除剤を改良しなければならないかもしれない。

　ゴキブリ駆除剤の多くは、食い付きを良くするため、ブドウ糖で包んでいる。しかし、約２０年前から効果が落ちたと指摘されていた。

　ゴキブリは物を食べる前に、口の周りにあるヒゲのような器官で触って味を確かめる。甘みを感じた時と苦みを感じた時で、神経回路の反応が異なり、苦みを感じた場合は食べない。

　勝又さんらは、７０００匹以上のゴキブリに、ブドウ糖や塩などを与えて神経回路の反応を調べた。通常のゴキブリはブドウ糖に甘みだけを感じるが、一部のゴキブリは苦みの神経回路が働くことがわかった。

（2013年5月26日22時33分 読売新聞）

 (試譯文)

While German cockroach should like sweet things, there was a type which did not eat them when it felt  the sweet taste as bitter taste; U.S. North Carolina State University Senior Research Scientist Ayako Katsumata and others published this in a U.S. science journal: the Science.

 
   It might be regarded as a survival strategy for escaping extinction by an extermination agent. An extermination agent might need improvement as a measure to deal with this cockroach.

   There were many cockroach extermination agents. In order that cockroaches might eat them, agents were improved to entice cockroaches into eating; agents were wrapped in grape sugar. However, it was indicated that this effect fell since about 20 years ago.

   Before a cockroach ate a thing, it would touch with an organ like the mustache surroundings the mouth to confirm the taste. The reactions of its neural circuit would differ when feeling sweetness and bitterness. It would not eat when bitterness was felt.

   Mr. Katsumata and others gave grape sugar and salt etc. to 7000 or more cockroaches, and he investigated the reaction of the neural circuit. Although the ordinary cockroach felt only sweet taste in grape sugar, it was found out that in some cockroaches the neural circuit felt bitterness.

It is an interesting scientific finding. The response of the cockroaches may be regarded as their survival strategy in order to avoid extinction