Neoseiulus californicus has been increasing in number and geographical distribution since the 1990s in Japan, and is considered to be a new prospective predator species against Panonychus citri on citrus. We investigated the occurrence of N. californicus in citrus orchards with different agrochemical spraying programs in Kyushu district, south-western Japan. The occurrence of N. californicus greatly differed among orchards. In conventional control orchards and agrochemical-reduced orchards, N. californicus females were observed in 50-60% of orchards. On the other hand, N. californicus females were rare in agrochemical-free orchards. N. californicus females were observed in all prefectures in the Kyushu district, but the occurrence of N. californicus was different among the § 果樹研究所業績番号：1465

A sex pheromone component of the Japanese mealybug, Planococcus kraunhiae, was isolated and identified. A crude extract of the pheromone obtained by airborne collection was first fractionated with Florisil column chromatography. The activity of each fractionated sample was examined in Petri dishes. The active fraction was further purified by HPLC and an active component was isolated by preparative GC. The purified compound showed attraction activity to adult males of P. kraunhiae in the field. The chemical structure was determined to be 2-isopropyliden-5-methyl-4-hexen-1-yl butyrate by GC-MS and NMR analyses.

Abstract. 1. Patch marks that allow the subsequent avoidance of marked areas may be used by small animals to increase foraging efficiency. This study is the first to demonstrate the presence of a patch-marking system in insect predators. Furthermore, the marking system is found only in females, and factors such as hunger state and patch quality play a key role in determining whether a female will re-investigate a self-marked patch.2. Females of the insect predator Orius sauteri avoided areas where the female itself had searched previously but did not avoid areas searched by conspecific females when deprived of prey for 24 h. There was no evidence that males use such a patch-marking system, indicating the presence of a sex difference in patch-mark use.3. Females did not discriminate between patches visited previously and patches not visited when they were either well fed or when patches contained abundant prey.4. The patch mark used by females was effective for 1 h and may be a reliable indicator of a recently visited area in which prey have been depleted.5. These results suggest that O. sauteri females have the flexibility to adjust their behavioural responses to a previously searched area depending on their hunger state and the availability of prey in their foraging environment.

In this study, we discovered and isolated an attractant for a mealybug-parasitic wasp Anagyrus sawadai from an esterification product prepared with commercialized lavandulol (2-isopropenyl-5-methyl-4-hexen-1-ol) and butyryl chloride. Using gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance spectroscopy, we determined the structure of the compound to be (2,4,4-trimethyl-2-cyclohexenyl)methyl butyrate (cyclolavandulyl butyrate). This is a novel compound as far as we know, although the alcohol moiety has been known as a cyclization product from lavandulol. Cyclolavandulyl butyrate has two enantiomers, and the (-)-isomer, which is suggested to have S configuration, showed higher attractiveness. A potential use for the A. sawadai attractant for mealybug management in agricultural fields is discussed.

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