| 研究実績の概要 |
Aphidophagous ladybird beetles are known to consume alternative foods from flowers, especially when prey is scarce. Flower-rich seminatural habitats in agroecosystems generally host a diversity of natural enemies, including predaceous ladybird beetles. This suggests that the availability of flowers may have a positive role in their fitness traits. In this study, we test that feeding on flowers of Perilla frutescens (Lamiaceae) increases longevity and fecundity in Harmonia axyridis (Coleoptera: Coccinellidae). The longevity of H. axyridis females and males fed with five flowers was significantly greater than those fed with one flower and in the control group, although the provision of flowers had no positive effect on the increase of body weight in males and females. The number of eggs and oviposition frequency in H. axyridis fed with flowers plus prey, as well as with prey only, were significantly larger than those fed with only flowers. Additionally, on the first day of the diet assignment, the number of eggs from individuals with the mixed diet was significantly higher than of those with only prey and those with only flowers, showing that flowers of P. frutescens, mixed with prey, have a positive effect on H. axyridis survival and early reproduction. This suggests that flowers may play an important role in increasing fitness in H. axyridis. The possibility of P. frutescens sown to support populations of the predator toward conservation biological control in a field is discussed.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
We will first assess in laboratory conditions the effect of feeding on Shiso on ladybeetle longevity by comparing three treatments: ladybeetles without food (control), ladybeetles with one fresh flower provided daily, ladybeetles with five fresh flowers provided daily. Second, we will test if feeding on Shiso flowers increases ladybeetle fecundity by comparing three treatments: ladybeetles fed with five fresh Shiso flowers daily only, artificial food only, and both. One male and one female will be placed in one petri dish and oviposited eggs will be counted.
We have already published above mentioned research and also related results at three international scientific journals.
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| 今後の研究の推進方策 |
We will first continue to assess Shiso attractiveness by monitoring the effect of ultra-violet reflectance by using photo-systems. Second, still in laboratory, we will test the effect of an early provision of Shiso flowers on ladybeetle longevity. Third, we will simulate a situation when ladybeetles finally find prey food.
In summer, field observations will be conducted in Kyoto and Okayama. Shiso and cabbage plants grown in pots will be used. Aphid abundance on cabbage and their natural enemies on both cabbage and visiting Shiso flowers will be monitored during the Shiso blooming period.
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