The effects of the host-tree defensive reaction and natural enemies on the larval mortality of the cryptomeria bark borer, Semanotus japonicus was examined by inoculation of newly-hatched larvae at different densities on 32 living Japanese cedar trees, Cryptomeria japonica half of which were screened to prevent attacks by natural enemies. Mortality due to natural enemies was not significant before the larvae began feeding on the sapwood, but appeared to be heavy during the phloem-sapwood feeding period. On screened trees, excluding two killed trees, the densities of larvae tended to become constant irrespective of the initial density at the starting time of feeding on the sapwood and at the completion of pupal chambers in the wood. Consequently, the survival rates decreased with increasing density. A hypothesis based on a time-delayed defensive reaction by host trees and variation in larval growth could explain the convergence of the larval densities.

View full abstract

The nemastatic effects of benfuracarb, a derivative of carbofuran, against the southern root-knot nematode (Meloidogyne incognita) were compared with those of carbofuran. Benfuracarb did not suppress juvenile migration in water agar at 100ppm, but suppressed aggregation and invasion to tomato roots at 5ppm. On the other hand, carbofuran suppressed juvenile migration at 10ppm and invasion at 5ppm, but did not suppress its migration and aggregation to tomato roots at 5ppm. These results suggested that benfuracarb has no suppressive action against nematode migration but inhibits invasion of tomato roots, whereas carbofuran possesses both activities. Accordingly, benfuracarb is considered to inhibit juvenile aggregation at totomato roots.

View full abstract

Adults of Anaphothrips obscurus and A. asahi living on wild grasses and on Artemisia princeps were sampled from June 1991 to May 1992 and from March 1990 to March 1992, respectively, in Kyoto to clarify the variability in relative wing length and seasonal changes in wing form composition. On the grasses, the adults of the two thrips species were usually found from spring to autumn and occasionally in winter, but on A. princeps, they were only found from January to April and in October. Macropterous, brachypterous and intermediate forms were recognized in female A. obscurus. In early spring, most females were brachypterous, and the proportion of the macropterous females increased during late spring and late summer. In both sexes of A. asahi, only the brachypterous form occurred throughout the study period. The annual cycle and overwintering sites of these thrips species, and factors affecting the seasonal changes in wing form composition of A. obscurus are discussed.

View full abstract

Three mealybug species, Pseudococcus citriculus, Planococcus citri and Planococcus kraunhiae were reared on citrus leaves to determine the lower developmental thresholds and thermal constants for each nymphal stage and preovipositional period at five constant-temperature regimes. Since few mealybugs developed to oviposition at 30°C, their higher developmental thresholds are around this temperature. The lower developmental threshold temperatures (T₀) and thermal constants (K) in the entire nymphal stage were 11.7°C and 338 degree-days (DD) for P. citriculus, 7.7°C and 401 DD for P. citri, and 8.0°C and 519 DD for P. kraunhiae. Those in the preovipositional period were 10.0°C and 302 DD, 8.0°C and 378 DD, and 11.4°C and 320 DD, respectively. These results for P. citriculus were used to calculate the effective cumulative temperature for each developmental stage. The seasonal development of nymphs and adult females of P. citriculus predicted using temperatures at Okitsu Branch, Fruit Tree Research Station from 1993 to 1994 matched the actual seasonal occurrence of the mealybug in a citrus orchard in those years.

View full abstract

In the field, eggs of Plutella xylostella are laid more on the cotyledon of Brassica napus seedlings than on the true leaf. Newly-hatched larvae were reared individually on seedlings with three true leaves. The larvae immediately moved from the cotyledon to the terminal folded leaf or the younger true leaf. Feeding sites in the larval stages changed frequently; the total number of inter-leaf movements was usually 4 to 8. Young larvae mainly used the terminal true leaf as feeding or resting sites, whereas middle-stage and mature larvae preferred other true leaves to the terminal leaf. A rearing experiment showed that smaller pupae are produced when larvae are fed on the cotyledon than on the true leaves, suggesting that the true leaf is more suitable as food in the larval stage than the cotyledon.

View full abstract

When Myrmecophilous species of cricket are newly introduced to an ant nest, or when the ant colony to which the cricket belongs is disturbed, the cricket is treated in a hostile manner by worker ants in most cases. The cricket escapes ant attack either by swift and nimble running or by using the ant cuticular hydrocarbon components, which serve as the nestmate recognition signal to worker ants. The cricket changes its cuticular hydrocarbon profile frequently according to the ant species it lives with. Lipids on the cricket cuticule mainly consist of hydrocarbons and wax esters, but only the hydrocarbon content decreases when the cricket is isolated from ants, suggesting that the hydrocarbons are acquired from the ants, it cannot change the cuticular hydrocarbon components. It is believed that the cricket acquires the ant cuticular hydrocarbons by direct contact with ant workers.

View full abstract

Lady beetle can walk on a vertically smooth surface such as a glass plate in the same manner as on a horizontal one. It was reported that the insect probably released a non-volatile lipid secretion from the spatulate ends of the tenent hairs and this secretion was essential to the adhesion process on smooth surfaces against the force of gravity. We have studied footprint chemicals which were secreted from the tenent hairs of the three species of lady beetles Epilachna vigintiocotomaculta, Epilachna vigintioctopunctata and Coccinella septempunctata. The component of footprints was species specific and consisted of hydrocarbons and true waxes. The footprint chemicals were just identical with those of the cuticular waxes. The waxes of footprints were secreted larger amount from the tarsus than that from cuticular surface.

View full abstract

The development and oviposition of the Kanzawa spider mite, Tetranychus kanzawai KISHIDA on leaves of five grape cultivars in an insectary, and the field population trends of the mite on four cultivars treated with permethrin and carbaryl were studied. High developmental success was observed on Muscat Bailey A (Vitis labrusca×V. vinifera×V. linsecumii) and Delaware (V. labrusca×V. vinifera×V. aestivalis) cultivars. On Kyohou (V. vinifera×V. labrusca), one quarter of tested larvae developed to adults. Only 2% of larvae developed on Muscat of Alexandria (V. vinifera) and no developmental success was observed on Neo Muscat (V. vinifera) and Campbell Early (V. labrusca×V. vinifera). Total egg production on Muscat Bailey A and Kyohou was larger than on Delaware, but no significant difference detected between Kyohou and Delaware. The population density of T. kanzawai also varied considerably between grape cultivars and spray practices. On permethrin- and carbaryl-sprayed vines, mite populations increased about 20 days after insecticide application. The cumulative numbers observed during the survey on insecticide-sprayed leaves were highest on Muscat Bailey A but remained low on Campbell Early. Kyohou and Delaware showed intermediate population densities. No population growth was observed on Neo Muscat. In non-sprayed controls, the mite populations remained at low levels of below three adult females per leaf on all cultivars.

View full abstract

To monitor the insecticide resistance of male adults captured in a sex-pheromone trap, the susceptibility to methomyl and permethrin was determined by topical application and residual film methods using susceptible (S) and resistant (R) strains of the common cutworm, Spodoptera litura FABRICIUS. Comparison was made between male adults and 3rd instar larvae. The resistance ratio of the R strain to methomyl with topical application was more than 1, 000 times for 3rd instar larvae, but only 8-9 times for male adults. The resistance ratio of the R strain to permethrin was 41 times for larvae, and 14 times for male adults. The resistance ratio of the R strain to methomyl and permethrin with the residual film method was very similar to that with topical application. Susceptibility to methomyl in male adults determined by topical application increased with age, whereas that determined by the residual film method did not change within 3-day ages. On the basis of these results, the residual film method is more suitable for monitoring insecticide resistance of male adults captured in a sex-pheromone trap.

View full abstract

The effect of fungicides and bactericides on Verticillium lecanii was evaluated both on agar plates, and on larvae of the greenhouse whitefly, Trialeurodes vaporariorum in the laboratory. Polyoxin, procymidone, sulfur, mepronil and copper hydroxide were harmless to conidial germination of the fungus on agar plates and showed no effect on the mortality of the insect when larvae were inoculated with a conidial suspension mixed with each. Triflumizole, dithianon, chinomethionat and zineb were highly toxic to conidial germination of the fungus on agar plates. However, when larvae were inoculated with conidial suspension mixed with each at a concentration sufficient to inhibit conidial germination, larvae were killed at percentages of 39%, 54%, 72% and 100%, respectively. Reduction of larval mortality by treatment with triflumizole was not observed 48h or more after inoculation. Polyoxin, sulfur, mepronil, procymidone, copper hydroxide, dithianon and zineb were harmless to mycelial growth producing conidia on the surface of larvae killed by the fungus, while triflumizole, chinomethionat, anilazine and benomyl were toxic to mycelial growth.

View full abstract

The suitability of freeze-dried, powdered larvae of the melon fly, Bactrocera cucurbitae (FPM) as a diet of Orius sauteri was compared to a diet of live 2nd instar larvae of Thrips palmi. O. sauteri was successfully reared on FPM but the developmental time, survival rate, longevity, preoviposition period and fecundity were negatively affected in comparison to a diet of live T. palmi larvae. The results show that FPM can be used as a diet for rearing O. sauteri but it is not as suitable as live T. palmi larvae.

View full abstract

Defoliation by Hyphantria cunea was surveyed in Tsukuba in 1988 and 1989. There was a significant positive correlation between the proportion of defoliation and the proportion of plant ground.

View full abstract