Food shortage is a prevalent threat to insect survival and successful reproduction in natural settings. An insect species invading new areasmay have a high capacity to survive and adapt to starvation. To test these hypotheses, we assessed the survival time of Corythucha ciliata (Say), in a laboratory under two starvation conditions: complete starvation (no food supplied) and gradual starvation (food provided once and not replenished). Under complete starvation, survival of 3rd to 5th instar nymphs tended to decline steadily, whereas under gradual starvation this process was delayed in the initial stage. The average survival times increased as the instar increased under both conditions (14.0 h, 15.9 h and 24.4 h under complete starvation conditions; 27.8 h, 29.6 h and 33.6 h under gradual starvation conditions). The longest lived individual nymph survived for 49 hours. The results may partially explain the rapid global expansion of C. ciliata.
The movement behavior of the pine needle gall midge (Thecodiplosis japonensis Uchida Et Inouye (Diptera: Cecidomyiidae)), an invasive species in China, was determined by using a tethered flight technique and digital videography in the laboratory. The flight distance, duration, and speed of females were compared at different ages (2–10 h) and ambient temperatures (17, 21, 26, and 30°C). Female flight distance and duration at 26°C were significantly greater than those at 17°C and 21°C. The age of T. japonensis did not significantly affect the three flight characteristics. For females at 2–10 h of age at 26°C and 70% RH, the maximum flight distance was 667.59 m; the longest flight time was 6,222.34 s; and the fastest flight speed was 0.44 m·s−1. For larvae wetted with water, the highest jump was 5.7 cm; the longest jump was 9.6 cm; and the greatest distance moved in 5 min was 27.13 cm, which showed that the active dispersal potential of larvae was very low.
Insect movement behavior is highly important in entomological population ecology, behavioral ecology and conservation, and in invasion ecology. In this study, we used an exotic lace bug (Corythucha ciliata) as a model organism to address the hypothesis that an insect species invading a new area has a high host location ability and rapid mobility by which it can be successfully carried to a new habitat. To test this hypothesis, three movement parameters (speed, duration and distance) of C. ciliata were assessed using laboratory and field observations. We found that 5th-instar nymphs of C. ciliata could move as far as 750 cm throughout their lifespan and that they moved an average of 0.038 m/min during the first 15 minutes after release, which was significantly farther than that of other instars. Of the tested nymphs, 21.85% could locate their host trees; of adults released 20 m from hosts, 11% reached the host trees on the first day, with an average flight distance of 22.14 m and a maximum flight distance of 27 m. The results of this study partly explain the mechanism of rapid diffusion. These results are also important for predicting population spread, improving eradication surveys, and managing future introductions of C. ciliata.
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