The rice leaf bug, Trigonotylus caelestialium (Kirkaldy), is a major species of stink bugs causing pecky rice. Seasonal prevalence of occurrence of this bug on rice plants in paddy fields was investigated by a sweeping method in Niigata Prefecture. The number of adult bugs captured by sweeping increased just after the rice plants reached the heading time, however it decreased quickly thereafter. The density of adults tended to be higher in an extremely early variety and an early variety of rice plant than a medium one. The number of males was more than the number of females, and the numbers fluctuated heavily. The nymphs appeared mainly from the middle to the end of the grain filling period. These nymphs originated from eggs laid by females which invaded the rice plants at the time of heading. The percentage of pecky rice grains tended to be high in the extremely early variety which showed a high hull-cracked rice rate. Most of the pecky rice grains were damaged at the top or suture of the grains. Hull-cracked rice began to appear 10 days after heading time and increased to the maturing stage. Pecky rice grains began to appear 15 days after the heading time. Damage at the top part of the grains did not increase after maturation. On the other hand, grains damaged at the suture increased markedly up to maturing stage.
A new pheromone formulation was developed to increase exposure time to insecticide for control of the sweet potato weevil. The formulation was a combination of sex pheromone, (Z)-3-dodecenyl(E)-2-butenoate, and an insecticide (MEP) impregnated into a blue ball (2 mm in diameter) made of the diatomaceous soil. The male weevils were attracted to the visual stimulation in addition to the sex pheromone. The attracted males located and tried to mate with the ball. They were thereby efficiently exposed to the insecticide for a longer time. The concentration of the new formulation was extremely low compared to the conventional formulations and therefore lower the cost of application.
The survival rate was investigated for pupae of Oligota kashmirica benefica, a predator of spider mites, defined as the ratio of emerged adults to mature larvae, placed in four different rearing materials. When light colored andosol (50 g) was used as a rearing material, the survival rate of the pupae was low (22.1–36.9%), irrespective of the amount of water (10, 20 or 30 g) added to the rearing material. This was also the case for survival rates in sand (100 g) to which 5, 10, 15 and 20 g of water had been added (33.3–50%). In contrast, relatively high survival rates (52.8–83.0%) were obtained with cellulose powder (20 g) to which 10, 20, 30, 40, 50 and 60 g of water had been added. High survival rates were also obtained with vermiculite (40 g) to which 10, 20, 30, 40 and 50 g of water had been added (77.5–88.5%). No adults were obtained when water was not added to any of the four rearing materials. These results indicate that cellulose powder and vermiculite are suitable materials for rearing pupae of this insect species.
We isolated an entomopathogenic fungus, Beauveria amorpha (Strain: HpBa-1), from Heptophylla picea larva. When the larvae were inoculated with HpBa-1, 90.0% cumulative mortality was obtained in 30 days. However, the cumulative mortality was low when the larvae were inoculated with Metarhizium anisopliae (Strain: PMA-7) isolated from H. picea larvae. The high virulence of HpBa-1 to H. picea larvae was analyzed by investigating the conidial adhesion and germination of HpBa-1 on larval cuticle. Numerous HpBa-1 conidia adhered to the H. picea cuticle and most conidia on the H. picea cuticle remained over time. HpBa-1 conidia germinated on H. picea cuticle 96 h postinoculation. However, few PMA-7 conidia adhered to the H. picea cuticle as compared to HpBa-1 and did not germinate on the cuticle 96 h postinoculation. From these results, conidial adhesion and germination on the cuticle of H. picea is one factor causing high virulence of HpBa-1 to the larvae.
A new technique for marking the rice leaf bug, Trigonotylus caelestialium was evaluated. Adults of the bug were dusted with powder of a fluorescent pigment (FX303, Sinloihi Co., Ltd. Japan) by dropping the bugs onto the powder. Fluorescence was observed by irradiation with an ultraviolet light or portable black light. Laboratory tests showed that the technique caused no significant side effects on survival and flight ability of the bug. The fluorescence remained at a detectable level for 20 d under field conditions.
The efficiency of pitfall traps was investigated using two size of enclosure (5 m×5 m and 10 m×10 m) in grassland under controlled population density of marked carabid beetles (Carabus insulicola insulicola Chaudoir, 1869) and different number of traps. Pitfall traps were evenly located in every enclosure. Checks on the pitfall traps were carried out every one or two hours on several days in July and August 2002. The efficiency of pitfall traps was correlated with the density of beetles, but not to the size of enclosure. In 5 m×5 m enclosure, the efficiency of individual pitfall traps was higher at about 2 m intervals of traps compared to 1 m, but the total number of caught beetles was higher at 1 m intervals than about 2 m. In this season this carabid beetle is nocturnal, but the activity of beetles was not steady. It increased rapidly from sunset to midnight and decreased by slow degrees from midnight to sunrise. It is thought that not all individual beetles were active each night, and that the activity patterns resulted from beetles reducing their activity according as individuals fed. From these results, a few points concerning the field research of this carabid beetle were suggested.
Seven species of Lepidoptera—Tortricidae: Adoxophyes honmai Yasuda, Lobesia aeolopa Meyrick and Strepsicrates semicanella (Walker); Geometridae: Ectropis excellens (Butler) and Hyposidra talaca (Walker); and Lymantriidae: Orgyia postica (Walker) and Lymantria dispar albescens Hori et Umeno—were reared from larvae injurious to Eucalyptus spp. (Myrtaceae) cultivated in Japan. A. honmai, L. aeolopa, E. excellens, H. talaca and Ly. dispar albescens were newly recorded as pests of Eucalyptus spp. Strepsicrates rhothia (Meyrick), which had been considered a pest of Psidium guajava in Japan, was shown from the male genitalic characters to be really St. semicanella, distributed in Malaysia and Australia. The record of occurrence of St. rhothia in Japan was expunged. St. semicanella, hitherto recorded in Japan only from Okinawa, was recorded from a greenhouse of cultivated eucalyptus trees at Nagoya, Honshu. The immatures were inferred to have invaded the greenhouse from young eucalyptus leaves transferred from Nago, Okinawa-jima Is. Larvae of the three tortricid and two geometrid species were illustrated, and the distinguishing characters among the tortricids were given. The genitalia and immature stages of St. semicanella were described for the first time.
The banana moth, Opogona sacchari (Bojer) is known as a pest of many tropical crops, fruits, and ornamental plants in Africa, Europe, the West Indies, Brazil, the southern United States, and elsewhere. It has rarely been recorded in Asia. Its first detection in Japan was in 1986 at the Moji Plant Protection Station, where larvae were found feeding on the stem of Dracaena sp. (Agavaceae). This moth was also spotted in Chichi-jima, Ogasawara, in 1999. However, through the identification performed in our laboratories, a number of records on this moth have accumulated from many localities in Japan. O. sacchari's presence in Japan appears to be in the warm regions of Honshu, Shikoku, Kyushu, and the Ryukyu Islands.
To demonstrate influence of water content of host tees on attacking behavior of Platypus quercivorus and on symbiotic fungi (yeasts and Raffaelea quercivora), the number of beetles landing on bait logs with their water content artificially changed and the number of entry holes bored by the beetles into the bait logs were counted, and the ratio of galleries with eggs or larvae and the ratio of wood pieces with the symbiotic fungi were investigated. A multiple regression analysis of the number of beetles captured and the number of entry holes bored by the beetles was performed with the length and water content of bait logs as explanatory variables. The result suggest that males land on bait logs by judging the length of bait logs or something related to their length, and that males bore into bait logs by judging both the length of the bait logs and water content of the bait logs at the time of breeding or by judging something related to both these factors. At a part with the low water content at the time of breeding, the number of entry holes per m2, the ratio of galleries with eggs or larvae, and the ratio of wood pieces containing symbiotic fungi were low, suggesting that P. quercivorus fails to reproduce in a part with low water content, because symbiotic fungi fail to propagate in this part. From the above, it is hypothesized that male P. quercivorus chooses host trees with large breeding capacity by a certain method, resulting in them tending to choose host trees where the symbiotic fungi grows easily because the water content is maintained for a long time.
Effects of light intensity on Bradysia paupera male mating behavior and upwind flight to female sex pheromone extracts were assessed in cage and wind tunnel tests. Typically the five behavioral components of mating behavior: wing fanning, zigzag approach, abdominal curing, body pivoting and copulation were not affected by light intensity at 500 lx and 1 lx. In wind tunnel tests, male upwind flight to the pheromone source was, however, remarkably inhibited by light intensity less than 100 lx. Lower light intensity at 1 lx significantly depressed male flight activity but not walking activity in the cage tests. The decrease in trap catches in the wind tunnel resulted from reduced upwind flight due to suppression of flight activity by low light intensity. A higher light intensity of 1,500 lx also showed a tendency to reduce male trap catches in the wind tunnel tests. These results suggest that the light conditions should be considered when pheromone traps are used in mushroom cellars and green houses to control or manage fungus gnats.