No abstract

Utilization of germinated broad bean seed (Vicia faba L.) as an alternative oviposition substrate for Orius sauteri (Poppius), a candidate biological control agent against thrips, was investigated under condition of 24°C and 16L : 8D. O. sauteri could lay eggs in a juvenile root of germinated broad bean seed provided as an oviposition substrate and these eggs could hatch with 97.1% hatch rate. Both nymphs and adults of O. sauteri were successfully reared on diet of the Mediterranean flour moth eggs (Ephestia kuehniella Zeller) with germinated broad beans as an oviposition substrate and without supplemental water supply. Mean developmental time from hatching to adult eclosion was 12.9 days for males and 13.3 days for females. Mean longevity of ovipositing females was 41.5 days and the total mean number of eggs laid per female was 108.7. Germinated broad beans could provide water and were suitable as an oviposition substrate. Germinated broad bean seeds with eggs could be stored at 2.5°C to 12.5°C for one week and these eggs could hatch at high rates. Thus, germinated broad bean seed appeared to be a suitable oviposition substrate for mass production of O. sauteri.

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.

Mealybugs, which include several agricultural pests, are small sap feeders covered with a powdery wax. They exhibit clear sexual dimorphism; males are winged but fragile and short lived, whereas females are windless and less mobile. Thus, sex pheromones emitted by females facilitate copulation and reproduction by serving as a key navigation tool for males. Although the structures of the hitherto known mealybug pheromones vary among species, they have a common structural motif; they are carboxylic esters of monoterpene alcohols with irregular non-head-to-tail linkages. However, in the present study, we isolated from the Matsumoto mealybug, Crisicoccus matsumotoi (Siraiwa), a pheromone with a completely different structure. Using gas chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy, we identified the pheromone as 3-methyl-3-butenyl 5-methylhexanoate. Its attractiveness to males was confirmed in a series of field trapping experiments involving comparison between the isolated natural product and a synthetic sample. This is the first report of a hemiterpene mealybug pheromone. In addition, the acid moiety (5-methylhexanoate) appears to be rare in insect pheromones.

The Japanese mealybug, Planococcus kraunhiae could be reared individually on germinated broad bean seeds as an alternative food source. The developmental period from egg stage to adult oviposition was 65 days at 20°C and 46 days at 24°C. Egg hatchability was higher than 98% at both temperatures. Survival rate from egg stage to adult emergence was 76% at 20°C and 81% at 24°C. The total number of eggs per female was 588 at 20°C and 965 at 24°C. Adult longevity of females at 20°C and 24°C was 32 days and 26 days, respectively. The suitability of germinated broad bean seeds for P. kraunhiae is discussed in comparison with other alternative food sources.