Trigonotylus Caelestialium Research Articles

イタリアンライグラス圃場におけるアカヒゲホソミドリカスミカメの卵寄生蜂の寄生率の消長

Egg parasitoids of the rice leaf bug, Trigonotylus caelestialium, and seasonal trends in parasitism by them were studied during 2000–2002 in Italian rye-grass fields, Joetsu, Niigata Prefecture, Japan. Oligosita sp. and Telenomus sp. were identified as the parasitiods of the bug eggs. Parasitism by each of these two egg parasitoids fluctuated widely between May and September.

合成性フェロモントラップによるアカヒゲホソミドリカスミカメの水田内発生消長の把握

The efficiency of a pheromone trap was evaluated as an alternative to the “sweeping method” that has been established as a monitoring method of the rice leaf bug, Trigonotylus caelestialium. A sticky trap, a plate with sticky surfaces on both sides, was used and a rubber septum impregnated with 0.01 mg of the synthetic sex pheromone was placed at the center of the upper side of the plate. The sticky traps were installed in paddy fields in Joetsu and Nagaoka, Niigata Prefecture and Toyama, Toyama Prefecture. The most effective trap height was estimated to be near the canopy of rice plants; therefore, the sticky trap was placed by poles at the height of the canopy in the center of a paddy field, and the traps were checked every day throughout the growing season in 2005. Monitoring by means of the sweeping method was also performed in the same fields at approximately five-day intervals. The number of adults captured by sweeping increased from the middle of June to early or mid-July, and then decreased, irrespective of region or rice variety, and the adults increased again at the heading time of each rice variety. The fluctuation pattern of males caught in traps and the number of males captured by sweeping were roughly synchronized in each paddy field. This result suggests that the pheromone trap can be utilized as a monitoring tool for the rice leaf bugs in paddy fields.

Seasonal Occurrence of Adults of Rice Leaf Bug Trigonotylus caelestialium (Heteroptera: Miridae) Caught by Synthetic Sex Pheromone Trap and Sweeping Method

Seasonal Occurrence of Adults of Rice Leaf Bug <I>Trigonotylus caelestialium</I> (Heteroptera: Miridae) Caught by Synthetic Sex Pheromone Trap and Sweeping Method

種子の吸汁がアカヒゲホソミドリカスミカメの幼虫発育と産卵数に与える影響

The effects of supplying grains as supplementary food on nymphal development and the fecundity of adults in the rice leaf bug, Trigonotylus caelestialium (Kirkaldy), were investigated under laboratory conditions. The emergence rate of adults was 3.3% when nymphs were reared on rice seedlings alone, while the rate was 93.1–96.7% when nymphs were reared on rice seedlings with wheat grains or hulled rice. As compared with bugs reared on wheat seedlings alone, the developmental periods of nymphs reared on wheat seedlings with wheat grains or hulled rice were shorter, and the forewing length of the emerged adults was longer. The number of eggs produced by females fed on wheat seedlings with grains was 3.3–5.2-fold that of females fed on wheat seedlings alone. It was concluded that grains are very important food for the rice leaf bug, and that grain feeding raises its reproduction rate. It is suggested that the availability of seeds on the host plant affects the development and fecundity of this bug.

Effects of Trap Height and Position on Male Catches of Rice Leaf Bug Trigonotylus caelestialium in Sex Pheromone Trap

Effects of Trap Height and Position on Male Catches of Rice Leaf Bug <I>Trigonotylus caelestialium</I> in Sex Pheromone Trap

Resistance to the rice leaf bug, Trigonotylus caelestialium, is conferred by Neotyphodium endophyte infection of perennial ryegrass, Lolium perenne

Abstract Neotyphodium fungal endophytes form mutualistic symbiotic associations with many grasses of the subfamily Pooideae, including important forage and turfgrass species. This relationship provides a competitive advantage to the host plant by increasing abiotic/biotic stress tolerance, such as its resistance to drought, diseases, and insect pests. The insect deterrent effects of endophytes are now receiving attention in Japan, as insect pests growing in meadows are causing problems in adjacent rice paddies. One of the most serious problems is the kernel spotting of rice grains caused by the rice leaf bug, Trigonotylus caelestialium Kirkaldy (Heteroptera: Miridae), which reproduces on Lolium species grown as forage. To determine the potential of Neotyphodium endophytes to reduce the invasion of rice crops by T. caelestialium from adjacent Lolium crops, we carried out choice and no‐choice feeding tests using endophyte‐infected and endophyte‐free clonal perennial ryegrass (Lolium perenne L.) (Poaceae). Our experiments revealed that the presence of the Neotyphodium endophyte strongly deterred the feeding of both first‐instar larvae and adults of T. caelestialium. These results show the potential of Neotyphodium endophytes to reduce the number of T. caelestialium in forage fields and grasslands, and thus to reduce the damage to rice grains caused by this insect pest.

Examination of Shape of Synthetic Sex Pheromone Trap in Rice Leaf Bug, Trigonotylus caelestialium

Examination of Shape of Synthetic Sex Pheromone Trap in Rice Leaf Bug, <I>Trigonotylus caelestialium</I>

Substantiation for Control of Rice Leaf Bug, Trigonotylus caelestialium (Heteroptera: Miridae) by One-Time Dispersion of Dinotefuran in Field

Substantiation for Control of Rice Leaf Bug, <I>Trigonotylus caelestialium</I> (Heteroptera: Miridae) by One-Time Dispersion of Dinotefuran in Field

アカヒゲホソミドリカスミカメの休眠卵率の季節的な推移と休眠卵産下に関与する環境要因

Seasonal changes in egg diapause induction and the effects of photoperiod and temperature on egg diapause in the rice leaf bug, Trigonotylus caelestialium (Kirkaldy), were examined using a population in Joetsu, Niigata Prefecture. The bugs were reared from egg to adult at five temperatures, ranging from 22 to 34°C, combined with eight photoperiods, ranging from 9L–15D to 16L–8D. The critical photoperiod for egg diapause induction fell between 13L–11D and 14L–10D at 25°C. However, the females reared at 28, 31 and 34°C deposited a large proportion of non-diapause eggs even if the photophase was shorter than 14 h. When the females laying diapause eggs were transferred to 11L–13D at 31°C, the number of females laying non-diapause eggs increased gradually on and after five days. Therefore, it is concluded that the females reared at a high temperature from the egg stage produce non-diapause eggs regardless of the photoperiod, and that a high temperature at the adult stage causes females laying diapause eggs to deposit non-diapause eggs. Seasonal changes in the proportion of diapause eggs produced by females collected in the fields were examined for three years, from 1999 to 2001. In 1999 and 2001, the percentage of diapause eggs increased gradually in September. However, the percentage of diapause eggs produced by the females collected on 20 September, 2000, decreased to less than 10%. It is considered that this phenomenon was caused by high temperatures for 4 days in the previous week.

Relationship between the Pecky Rice Damage Caused by Rice-Feeding Bugs (Trigonotylus caelestialium Kirkaldy) and Contents of Silica in Maturity Stage of Rice

Relationship between the Pecky Rice Damage Caused by Rice-Feeding Bugs (Trigonotylus caelestialium Kirkaldy) and Contents of Silica in Maturity Stage of Rice

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The rice leaf bug, Trigonotylus caelestialium (Kirkaldy), is an important species of stink bugs causing pecky rice. Control of this bug with fenitrothion is insufficient in paddy fields of Niigata Prefecture. Therefore, susceptibility to fenitrothion was assayed in populations sampled from seven regions of Niigata Prefecture in 2001 and 2002. LD50 values of five populations ranged from 50.6 to 146.2 μg/g, and these values were remarkably higher than 18.8 μg/g of the most susceptible population tested. I concluded that resistance to fenitrothion developed with continuous applications of fenitrothion.

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The attractiveness of synthetic sex pheromones of the rice leaf bug, Trigonotylus caelestialium (Kirkaldy), was evaluated in the field. The rubber septum was soaked in synthetic sex pheromone, mixture of n-hexyl n-hexanoate, (E)-2-hexenyl n-hexanoate, n-octyl n-butyrate in ratios of 100 : 40 : 3. The rubber septum was used as a lure and was hung on a water pan trap about 10 cm above the water surface. The attractiveness of the synthetic pheromone at 0.001 mg and 0.01 mg per rubber septum to males was equal to that of 10 virgin females. The rubber septum impregnated with 0.01 mg synthetic pheromone remained attractive to males for one month.

Population Estimation of the Rice Leaf Bug, Trigonotylus caelestialium (Kirkaldy), with Mark and Recapture Methods

Population Estimation of the Rice Leaf Bug, <I>Trigonotylus caelestialium</I> (Kirkaldy), with Mark and Recapture Methods

The sex pheromone components for mating disruption of the rice leaf bug, Trigonotylus caelestialium (Heteroptera: Miridae)

The sex pheromone components for mating disruption of the rice leaf bug Trigonotylus caelestialium were examined in both the laboratory and the field. A rearing cage test in the laboratory showed that the copulation rate of T. caelestialium adults in cages treated with a dispenser loaded with the synthetic sex pheromone, a mixture of n-hexyl n-hexanoate, (E)-2-hexenyl n-hexanoate, and n-octyl n-butyrate (100 : 40 : 3), was lower than that of bugs in untreated cages, and that populations of the next generation were also reduced. In small-scale field tests (9 dispensers loaded with 50 mg of the sex pheromone placed at 5 m intervals in a 10 m×10 m square area), the numbers of males captured by traps baited with a lure containing the three components of the sex pheromone were reduced to some degree by treatment with either n-hexyl n-hexanoate or (E)-2-hexenyl n-hexanoate alone, or a 100 : 40 mixture of these two components. Furthermore, male capture by traps baited with the lure were mostly reduced by treatment of the 3-component sex pheromone, and also those baited with 3 virgin females. In large-scale field tests (200 dispensers each containing 300 mg of the 3-component sex pheromone in an area of 10,000 m2), the population densities of T. caelestialium and the numbers of males captured by traps in the treated fields were lower than those in the untreated fields.

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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.

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Effects of aging and copulation on the flight ability of the rice leaf bug, Trigonotylus caelestialium (Kirkaldy), were investigated by a tethered flight technique. Three day old unmated females showed the longest total flight duration per 1 h. A high flight activity in 3 day old females appears to be closely related to mating behavior. There was little difference in the flight activity of unmated males at all ages. The flight activity in 5 day old females was similar to 5 day old unmated females. Therefore, mating status does not appear to affect the flight activity of females. We conclude that the flight activity of adult bugs is low and they repeat short flights in their habitats and among the host plants in the field.

Growth and Oviposition of the Rice Leaf Bug, Trigonotylus caelestialium (Kirkaldy) (Heteroptera: Miridae), on Gramineous Weeds and Italian Rye Grass

Growth and Oviposition of the Rice Leaf Bug, <I>Trigonotylus caelestialium</I> (Kirkaldy) (Heteroptera: Miridae), on Gramineous Weeds and Italian Rye Grass

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Cultivars ‘Ishikari’ and ‘Hoshinoyume’ showed a stable high split-hull paddy rate regardless of location or year, while the rate was relatively low in ‘Kirara 397’ and ‘Yukihikari’. In both ‘Hoshinoyume’ and ‘Kirara 397’, split-hull paddies began to appear 3–4 weeks after emergence of the panicle neck (i.e. after the dough ripe stage) and reached a peak 5–7 weeks after that stage. In normal paddies (=without split-hull paddies), Trigonotylus caelestialium produced more pecky rice grains at the flowering to milk-ripe stage or at the milk ripe stage, then decreased as the growing stage proceeded. Most of these pecky rice grains were damaged at the top part of the grain. However, the occurrence of pecky rice grains did not decrease remarkably with growth of the ear in split-hull paddies. Most pecky rice grains were injured on the side of the grain, and it was also verified that each injury site coincided with the split part of the paddy. These results indicate that T. caelestialium fed from the split part or joint (particularly the top of the joint) of the hull. Furthermore, this bug had difficulty in attacking grains as the growth of the ear progressed, although it was able to attack hardened grains (i.e. after the yellow ripe stage) in the case of split-hull paddies.

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The rice leaf bug, Trigonotylus caelestialium (Kirkaldy), is a plant feeder which feeds on gramineous grasses. It has been confirmed that the conspecific eggs are sucked dry by female and male adults. This egg predation indicates the bug is omnivorous. Fecundity and longevity of adults served wheat seedlings, as both a food source and oviposition site, were examined at 30°C, 25°C and 20°C with a 16-h photophase. The mean preoviposition period at 20°C was significantly longer than at 30°C and 25°C. The averages of the total number of eggs laid per female were 127.3, 107.7 and 107.6 at 30°C, 25°C and 20°C, respectively. Both females and males lived longer at lower temperatures. Males tended to live longer than females under all temperature conditions.

Preference to Spring Gramineous Weeds and Italian Rye Grass as Food of Trigonotylus caelestialium (Kirkaldy) (Heteroptera: Miridae)

Preference to Spring Gramineous Weeds and Italian Rye Grass as Food of <I>Trigonotylus caelestialium</I> (Kirkaldy) (Heteroptera: Miridae)