The oviposition site and development of Halyomorpha halys and Homalogonia obtuse were examined in apple orchards from 1997 to 2000. Many egg batches of both species were found on the apple leaves. When adults of both species were released on the apple trees in late May, progeny adults emerged the middle of August. Larvae fed on the current shoots, leaves and fruit. Half of the overwintering female adults of Ha. halys that immigrated to the apple orchards had mature eggs. Ha. halys adults right after overwintering that were released on the apple tree in early May began to oviposit on the apple leaves starting in early June. These observations suggest that apple trees can be one of the early host plants for both Ha. halys and Ho. obtusa.
The adult density of the tea rust mite, Acaphylla theavagrans Kadono, on tea leaves at different levels and the reproductive rate of the mite were investigated in the laboratory using different tea varieties and lines. The adult density of the mite was highest on the 4th to 5th leaves from the terminal leaf. Laboratory experiments revealed that females laid more eggs on the middle leaves. The difference in the adult density in relation to the leaf order was mainly caused by a difference in the oviposition rate of the mite since the number of eggs laid per 20 females for 3 days was the highest on the 5th leaf. Among the 8 Japanese cultivars, the number of eggs laid per 20 females for 3 days varied from 34.8 on the ‘Kuritawase’ to 97.8 on the ‘Ooiwase’ and were significantly different among the varieties. Large differences in the number of eggs were found among the 9 introduced tea lines, ranging from 3.5 on the ‘Miya taiwan-yamacha’ to 63.5 on the ‘Chinshindapan.’ Moreover, the intrinsic rate of natural increase varied from 0.1559 on the ‘Miya taiwan-yamacha’ to 0.1973 on the ‘Chinshindapan.’
Developmental zeros and effective heat units of Eysarcoris aeneus (Scopoli) were calculated from its developmental periods at different constant temperatures. The developmental zeros were 13.7°C in the egg, 10.2°C in the egg and nymph, and 17.0°C during the preoviposition period. The effective heat units were 66.7 day-degrees in the egg, 500.0 day-degrees in the egg and nymph, and 73.5 day-degrees in the preoviposition period. The number of annual generations of E. aeneus was estimated based on these data and the meteorological data for 20 years recorded by an AMeDAS system with six observation points in Ishikawa Prefecture. The number of annual generations was estimated to be two or three, differing between years or areas. Analysis of overwintered adult density surveyed in 50 grassland fields for nine years showed a significant positive correlation (r=0.81) between the annual effective heat unit for E. aeneus in each year and the overwintered adult density in the following year.
In order to develop a new strategy for control of B. paupera, a serious pest insect in production of mushroom, Agaricus bisporus the mating behavior and related regulatory factors were elucidated in laboratory experiments. Mating behavior was analyzed by observation of 75 pairs of cultured flies. The typical mating sequence was: 1) beginning of male intermittent wing fanning (WF), 2) walking in a zigzag approach (ZA) while continuing WF, 3) abdominal curling (AC) forward beneath the thorax while opening claspers to grab female abdomen when near the female, 4) pivoting 180 degrees around body axis (P180), 5) mating occurrence (MO). This sequence was very stereotypical whereas the females exhibited no characteristic synchronous actions. Mated females refused copulation with subsequent male copulation attempts by kicking the male off with the hind legs or escaping the males mating attempts. Bioassay results demonstrated that a female produced volatile sex pheromone evokes typical male copulating behavior. The threshold activity of the crude female extract eliciting WF and ZA in males was shown to be 2×10−3 female equivalents (FE) in the tube assay. Attractive activity of female extract was corroborated in wind tunnel assays. Male flies showed WF, ZA, and AC responses to all parts of the female body. Effects of female age on male responsiveness to pheromones seemed non-critical, because males demonstrated all responses (WF, ZA, AC) whenever exposed to females from the teneral period to 3 days after emergence. Males responded to melanized pupae with WF and ZA. In male flies, sexual responses began 30 min after adult eclosion, and increased to a maximum 2 h after emergence.
Detailed mating behavior of the persimmon fruit moth, Stathmopoda masinissa Meyrick (Lepidoptera: Oecophoridae); female calling time, mating time, mating duration, and male response to virgin females and their abdominal extracts were investigated under controlled laboratory conditions. Female moths typically exposed their abdominal tips for calling, and males responded by showing a series of 4 behavioral components; fierce antennal swing (AS), orientation flight (OF), mating dance (MD), abdominal contact (AC) and copulation (CP). The maximal calling and mating was concentrated at the end of scotophase. Time profiles of these behaviors were affected by adult age as well as generation tested. Crude extracts of female abdominal tips significantly elicited a series of reproductive behaviors from male moths. The hind femural hair-tuft of both sexes seems to not be related to the mating behavior. Pheromonal activity of the female abdominal extract increased with the dose of the extract up to 5 female equivalents. The threshold doses for MD and AC were significantly higher than those for AS and OF.
The degree of damage and the time of injury by fruit-piercing stink bugs was investigated in various apple cultivars (Malus pumila Mill. var. domestica Schneid.). In 1996, the degree of damage by stink bugs was significantly high in the early-harvest cultivar, Sansa and the mid-harvest cultivars, Starking delicious and Hokuto. In 1998, the damage by released Halyomorpha halys (Stål) was investigated every 10 days from 10 June to 20 September and shown to be heavier in early- and middle-harvest cultivars than in late-harvest cultivars. These results suggest that the degree of damage by stink bugs differed among apple cultivars even if the apple fruits were damaged at the same time within an year.
A census by sweeping in Joetsu (37°06′N, 138°16′E), Niigata Prefecture, Japan, showed that early instar nymphs and adults of the rice leaf bug, Trigonotylus caelestialium (Kirkaldy), occurred on the levees covered with weeds in early November. To determine if nymphs and adults found in late autumn overwinter in the field, bugs collected from the levees in late October to November were confined to a cage along with seedlings of Italian rye grass, Lolium multiflorum, and maintained under natural conditions. No bugs survived until late March of the following year. This indicates the nymphs and adults occurring in late autumn in the field are not likely to overwinter.
To evaluate the effect of predation by a water strider Geriss nepalensis (Hemiptera : Geriidae) on the population fluctuation of the leaf beetle Galerucella nipponensis (Coleoptera : Chrysomeridae) on an aquatic host plant Trapa japonica in the field, availability of the leaf beetle as prey for the water strider was examined in the laboratory. Beetle larvae of the 1st, 2nd and 3rd instars on leaves of T. japonica rosette were exposed to a pair of water striders with alternative prey, a blow fly Lucilia illustris, or without alternative prey. The survival rate of the larvae without the alternative prey was significantly lower than that with the alternative prey. A similar experiment was also conducted for the eggs of the beetle. A few eggs were sucked by the water strider when the predators were extremely hungry under the conditions without the alternative prey. These results show that quality of the beetle as prey for the water strider is relatively low, however, the beetle will be attacked by the water strider in the field when abundance of suitable prey is low.