. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 160 120 80 E E c o 40 .9- o 0 Jan Feb Mar Apr May June July Aug. Sepl Ocl Nov Dec FIGURE 2. A. Flight activity of field collected beetles at monthly intervals from Mar .-Dec., 1977. Open circles, solid line = flight activity of beetles collected in aphid infested fields around Austin, Texas; closed circles, solid line = flight activity of beetles collected on top of Mt. Locke in the Davis Mountains of western Texas; open circles, dashed line = monthly precipitation in the Austin area, , 1977. B. Flight activity of C
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 160 120 80 E E c o 40 .9- o 0 Jan Feb Mar Apr May June July Aug. Sepl Ocl Nov Dec FIGURE 2. A. Flight activity of field collected beetles at monthly intervals from Mar .-Dec., 1977. Open circles, solid line = flight activity of beetles collected in aphid infested fields around Austin, Texas; closed circles, solid line = flight activity of beetles collected on top of Mt. Locke in the Davis Mountains of western Texas; open circles, dashed line = monthly precipitation in the Austin area, , 1977. B. Flight activity of California beetles obtained in Nov. and again in June from Bio-Control Co. and held at 7° C until 3 days prior to the flight test. Beetles were tested at monthly intervals, 3 days after being placed in a 16L: 8D, 24° C environmental regime. beetles collected from Mt. Locke in July and August displayed only a 20% migratory population. The proportion of long flights declined through the last collection, which occurred at Mt. Locke in December (See Fig. 2A). These data suggest a periodic change in willingness to make long flights within the H. convergens population. We were interested in investigating this possibility more directly. California beetles which were obtained from Bio-Control in Novem- ber, 1978, and maintained at 7° C were periodically removed from the low-tempera- ture incubator, held for 3 days at 24° C, 16L:8D, and then flight tested. A sig- nificant change in the proportion making long flights was observed over the 11- month testing period (Fig. 2B). Not surprisingly, the pattern of change under these highly artificial conditions was not identical to that observed in the field- collected animals. However, a marked increase in flight activity did occur from February to June. The proportion of animals making a long flight was 20% in January, rose to 30% in February, and increased to nearly 60% during March, April, and May. By the June flight tests the proportion
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
