The sorghum plant bug Stenotus rubrovittatus (Matsumura) (Heteroptera: Miridae) is a major seed pest of rice in Japan. Male S. rubrovittatus were previously shown to be attracted to traps baited with unmated females. The solvent extract of unmated females was analyzed by GC-MS using HP-INNOWax and HP-5ms columns, and retention index data and mass spectra of peaks detected in the female extract were compared with those of authentic samples. Three compounds, hexyl butyrate (ϭbutanoate), (E)-hex-2-en-1-yl butyrate and (E)-4-oxohex-2-enal, were identified from the female extract. Contents of these compounds in solvent extract of females were ca. 18.6, 8.6 and 1.0 mg/female, respectively. In a field experiment, a blend of three compounds showed potent attractant activity to male S. rubrovittatus, although no binary combinations of the three components were attractive. These results suggested that these compounds are components of the female sex attractant pheromone of S. rubrovittatus.
We quantified differences in leaf traits between upper and lower crowns of a deciduous oak, Quercus acutissima, and examined feeding preference, consumption and performance of the Japanese oak silkmoth, Antheraea yamamai, for those leaves. Upper-crown leaves had significantly smaller area, larger dry mass per area, greater thickness, lower water content, higher nitrogen content and a higher N/C ratio than lowercrown leaves. When simultaneously offered upper-crown and lower-crown leaves, moth larvae consumed a significantly larger amount of the former. However, when fed with either upper-crown or lower-crown leaves (no choice), they consumed a significantly larger amount of the latter. Female larvae reared on uppercrown leaves had a significantly smaller fresh weight, but attained a significantly larger pupal fresh and dry weight, with a significantly higher relative growth rate than those on lower-crown leaves. Although, like female larvae, male larvae had a significantly smaller fresh weight when reared on upper-crown leaves, they had a significantly larger value only for pupal dry weight. These results suggest that: (i) larvae ingest a greater amount of lower-crown leaves to compensate for the lower nitrogen content of the foliage, resulting in having an excess of water because of the higher water content of the foliage; (ii) feeding preference for upper-crown leaves accords with better performance (with respect to dry pupal weight and relative growth rate) on the foliage; (iii) better performance is explained by a higher nitrogen content and N/C ratio of the upper-crown foliage; and (iv) the effects of leaf quality on performance differ between sexes.
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