Hironori Sakurai

Synchronous growth of a parasitoid, Perilitus coccinellae, and teratocytes with the development of the host, Coccinella septempunctata

The relationship between the development of Coccinella septempunctata brucki Mulsant (Coleoptera: Coccinellidae) and its parasitoid, Perilitus coccinellae (Schrank) (Hymenoptera: Braconidae) was studied at two photoperiods (L16:D8 and L12:D12) at 26 °C. The development of P. coccinellae is well synchronized with the physiological state of the host, C. septempunctata, which can be parasitized not only as adult but also as larva or pupa. The parasitoid larva completed larval development within 19 days in a non‐diapausing host, while in diapausing adults as well as in pupae held at diapause‐averting conditions, the parasitoid larva ceased growth at the first instar. Growth was resumed when diapause of the host terminated or by the emergence of the adult host from the pupa.

Sex pheromone of the persimmon fruit moth, Stathmopoda masinissa: Identification and laboratory bioassay of (4E, 6Z)-4,6-hexadecadien-1-ol derivatives

Three electroantennogram (EAG)-active components were detected by gas chromatography coupled to an electroantennographic detector (GC–EAD) analysis of a hexane extract of the pheromone glands of the persimmon fruit moth, Stathmopoda masinissa. These compounds were identified as (4E,6Z)-4,6-hexadecadienal (E4,Z6-16:Ald) and the corresponding acetate (E4,Z6-16: OAc) and alcohol (E4,Z6-16:OH) by mass spectral, GC retention time (RT), and microchemical test data. The characteristic base peak of the aldehyde at m/z 84 provided a crucial piece of information suggesting the possibility of a 4,6-diene structure. The (4E,6Z)-isomer elicited the strongest EAG responses among the four geometrical isomers of each synthetic 4,6-hexadecadienyl compound. In a laboratory bioassay, only E4,Z6-16:OAc elicited male moth behavioral activity significantly different from the control; the activity of the acetate was not affected by addition of the aldehyde and alcohol. A preliminary field trial confirmed that E4,Z6-16:OAc as a single component attracted male moths. The possible roles of E4,Z6-16:Ald and E4,Z6-16:OH as components of lures for field use remain to be determined.

The species composition and diversity of tree-dwelling beetles in deciduous oak and evergreen forests in central Japan; Relationship between the diversity index and sample size

During the period fromlate May through December 1981, tree-dwelling beetles were regularly surveyed at three deciduous oak and two evergreen forests in the vicinity of Gifu City. Chrysomelidae and Curculionidae were abundant in these forests. The species diversity and the seasonal succession of species were most apparent in May and June. The three deciduous oak forests, with many species and high equitability, showed more diverse community structure, but fewer individuals, when compared with the two evergreen forests. Furthermore, the species compositions of the deciduous oak forests were seasonally and spatially more heterogeneous than those of the evergreen forests. A few dominant species, however, had a strong influence on the community structure. The relationship between the diversity index and sample size was examined. The diversity index changed with the sample size, and the range of the variation diminished as the sample size increased. However, equilibrium was not reached even in the largest sample size used in this study (20 samples). There was a significantly high correlation (P<0.001) in diversity index between the smaller sample sizes (5, 10, 15) and the largest. It was, therefore, shown that community structures can be compared on the basis of the diversity indices from samples of constant size, even when the samples are small.