The morphological and behavioural effects of precocene II on Locusta

The precocious adultiform larvae produced by topical applications of precocene II to early 4th instar Locusta were found to be intermediate between normal 5th instar larvae and normal adults on behavioural as well as morphological criteria. Precocious adultiforms walked significantly smaller distances in 2 hr than normal larvae, but slightly more than normal adults. The adultiforms jumped significantly greater distances without wing movements than normal larvae, but they also made frequent, short, adult-type jumps with wing movements. Most advanced adultiforms made jumps of both types whereas normal adults made only a small percentage of the larval-type jumps. Apparently the central nervous organisation of the adultiforms provides equally and separately for both larval and adult behaviour patterns, rather than compounding the two. Increasing doses of precocene above 100 μg produced more advanced adultiforms, and there was some indication that morphologically similar types produced by different doses may differ in their behaviour.