The effects of temperature, age and mating status on the flight activity of Carposina sasakii were examined using a flight mill system. Flight measurements were carried out for 24 h under dark conditions. No significant difference was observed for the total flight duration of 2-day-old moths at temperatures between 14 and 26°C. The proportion of individuals that did not fly at all was less than 10% at 14 to 29°C, whereas the proportion at 11°C was 67% in females and 83% in males. Total flight duration did not show a significant difference through the ages from 1 to 7 days in either sex. Two-day-old females flew significantly faster than 1-day-old females, whereas flight speed did not differ among ages in males. Flight activity of females was similar to that of males and remained high even after mating. These results are discussed in relation to the control of C. sasakii by mating disruption in the apple orchards.
Larval survival and development of Carposina sasakii were examined in apple fruits. Irrespective of the oviposition date between early June and late August, larval survival in apple fruits was low (0-20.8%). The duration from oviposition to larval emergence from the fruits varied greatly from about 30 d to more than 100 d. When eggs were laid after late June, some larvae remained in the fruits until harvest in late October or early November. The larval survival rate differed significantly depending on whether the fruit was picked from the tree. The survival rate of larvae that entered "unpicked" fruits in early July was only 6.3%. However, 72.1% of larvae successfully emerged from fruits that were picked immediately after larval entry, although these fruits were maintained under the same field conditions as the "unpicked" fruits. Larval emergence from "picked" fruits was more synchronous than that from "unpicked" fruits. These results suggest that low survival and the retardation of larval development are caused by factor(s) related to fruit growth, which remains to be detected.
Spraying a calcium carbonate suspension "White Coat" on the fruit of apples significantly suppresses the oviposition of the peach fruit moth, Carposina sasakii. In gas chromatography (GC) with an electroantennographic detector analysis, adult female antennae showed responses to three compounds that were identified as 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (TXIB) and its two mono-hydrolyzed analogs, texanols (1-and 3-isobutyrates), all added as a plasticizer to the agents. An oviposition-choice test using adult moths revealed that TXIB has clear deterrent properties when applied to young apple fruits. Video recording analysis showed that female moths spent longer on self-grooming and searching around TXIB-treated fruits. In the same assay, pure calcium carbonate treatment prevented the moths from climbing up or landing on the fruits, while such was not the case with White Coat-treated fruits. TXIB, an adjuvant aimed to provide rain/wind resistance, weakened the slipperiness of the calcium carbonate coating but, coincidentally, maintained the oviposition inhibitory activity of the White Coat by its deterrent odorant.
Apples Malus domestica, known as a rich source of triterpene acids, induced more variety and quantity of triterpene acids in response to herbivory or mechanical damage. There were three major induced compounds: pomaceic acid and euscaphic acid, both of which are known apple triterpene acids, and 2α,19α-dihydroxy-3-oxours-12-en-28-oic acid (named eriobotoric acid), which was first identified in apples. In this study, the three compounds’ induction curves after damage, varietal differences in induction amounts, and physiological roles against pest insects were further investigated. Eriobotoric acid showed clear antifeedant activity against lepidopteran insect Spodoptera litura but not against apple pests.
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