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Volume 38 (1994)
- Issue 4 Pages 219-
- Issue 3 Pages 141-
- Issue 2 Pages 65-
- Issue 1 Pages 1-
Volume 38, Issue 1
Displaying 1-7 of 7 articles from this issue
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I. Adaptive Significance of Egg-Covering Behavior by Adult FemalesTakeshi SHIMODA, Norizumi SHINKAJI, Hiroshi AMANO1994 Volume 38 Issue 1 Pages 1-6
Published: February 25, 1994
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe materials used for the egg-covering behavior of adult females of Oligota kashmirica benefica NAOMI, a natural enemy of spider mites, were investigated on leguminous arrowroots, Pueraria lobata (WILD.) OHWI, in 1989-1991. Most eggs (93.3%) on leaves collected in the field were covered, partially or completely, with a pile of debris (feces, skins, egg shells and dead bodies of Tetranychus spider mites), but prey eggs were rarely used as egg-covering materials. Females of a closely-related species, O. yasumatsui KISTNER, also showed similar behavior with the same materials. A series of experiments was conducted under laboratory conditions at 25±1°C to evaluate the adaptive value of this egg-covering behavior. Covered eggs were preyed upon less frequently by their predators (Stethorus japonicus KAMIYA, Scolothrips takahashii PRIESNER, and Amblyseius longispinosus (EVANS) etc.), compared to uncovered eggs as well as eggs covered articially with prey eggs. On the other hand, egg-covering hardly influenced hatchability at various humidities. These results suggest that egg-covering plays a significant role in protecting eggs from attack by predators rather than in protecting them from harsh physical conditions (e.g. desiccation).View full abstractDownload PDF (2031K) -
Tomonari WATANABE, Kazushige SOGAWA, Yoshito SUZUKI1994 Volume 38 Issue 1 Pages 7-15
Published: February 25, 1994
Released on J-STAGE: March 31, 2009
JOURNAL FREE ACCESSYearly changes in the occurrence of long-distance migratory planthoppers were analyzed from light trap data recorded at Chikugo in Fukuoka Prefecture for 40 years from 1951 to 1990. The number of catches at the immigrant generation (G0) and three successive generations (G1, 2, 3) were identified on the basis of effective heat units required for completing one generation. Annual catches of N. lugens showed a downward trend throughout the 40-year period, but annual catches of S. furcifera increased from the mid 1970s. The variances of G0 and G1-3 in N. lugens were the largest in 1980s. The variance of G0 in S. furcifera was also the largest in the 1980s, but that of G1-3 decreased consistently after the 1960s. Negative relationships were found between G0 and population growth rate (G1-3/G0) for both planthopper species. The rate of density-dependent reduction of the population growth rate in S. furcifera in the 1980s was greater than in the other decades. Population growth patterns from G0 to G3 were classified into three groups according to the 1st and 2nd component scores of principal component analysis for both species. Groups I and II differed in the population growth rate of successive generations, although the immigrant density was similar. The causes of the difference were the initial date of immigration and the August temperature for N. lugens, and September precipitation for S. furcifera. Group III was characterized by a high G0 and low population growth rate.View full abstractDownload PDF (1114K) -
Hiroya HIGUCHI1994 Volume 38 Issue 1 Pages 17-21
Published: February 25, 1994
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSEgg masses laid by Piezodorus hybneri were checked every three days from June to August in 1988-1990 in a soybean field in Kyushu, Japan. The mortality factors of eggs were investigated in 1989 and 1990. Egg masses found in the field were left for 6 days to check hatching 3 and 6 days later. The egg masses were then collected and kept in laboratory until parasitoids emerged. The density of egg masses increased just after soybean plants reached the pod-development stage and egg masses were found until about 45 days after flowering. Females of P. hybneri tended to lay eggs on pods of soybean plants; more than 55% of egg masses were found on pods. The number of eggs per egg mass ranged from 2 to 47 with a mean (±SD) of 20.4±8.4. The most important mortality factor was parasitism by Telenomus triptus. The percentage parasitism was estimated at 91.3% in 1989 and 78.0% in 1990. Percentage parasitism by T. triptus was high regardless of the size of egg mass. Ooencyrtus nezarae was another egg parasitoid emerging from P. hybneri eggs. However, the percentage parasitism was very low below 2.5% in both 1989 and 1990. Eggs often disappeared in the field suggesting another important but unknown mortality factor.View full abstractDownload PDF (702K) -
Keiichiro YASUMI, Katsuaki OHBA, Chisato HIRANO1994 Volume 38 Issue 1 Pages 23-28
Published: February 25, 1994
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe structure of the mouthparts of adult female Thrips palmi KARNY was examined under a scanning electron microscope. The mouthparts form a broad proboscis called the mouthcone consisting of anteclypeus, labrum, maxillary lobes and labium. The mouthcone apex is usually covered by a membraneous labial lobe, paraglossa, with more than 10 pairs of hooks (possibly sensory hairs). When feeding, the insect retracts the covering paraglossa laterally and protracts three stylets on the exposed apex. The stouter mandibular stylet, about 1.7μm in diameter at the base, is thought to puncture holes through the plant epidermis. The slender, paired maxillary stylets seem to combine with each other lengthwise to form a long tube, about 1.7μm in diameter, for sucking cell sap. A large concave structure, possibly a labral pad, is located around the stylets on the exposed mouthcone apex. After examination of injured leaves, only a few feeding marks, about 2μm in diameter, were found on all collapsed epidermal cells. No destroyed, torn or gashed cells, or exposed cell content were observed at all. The morphology of mouthparts, and the feeding marks on injured leaves indicate that T. palmi is a true sap feeder with no biting behavior.View full abstractDownload PDF (2231K) -
Yôzô MURAKAMI, Takaaki HIRAMATSU, Masataka MAEDA1994 Volume 38 Issue 1 Pages 29-41
Published: February 25, 1994
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSTo predict the possible effect of native parasitoids on the effectiveness of an introduced parasitoid, native parasitoid complexes of the chestnut gall wasp, Dryocosmus kuriphilus were investigated in Miyagi (38°10′N) and Okayama (34°50′N) Prefectures where T. (S.) sinensis has not yet occurred. The results were compared to those from a chestnut orchard in Kumamoto Prefecture (31°50′N) where the parasitoid has already been released and become established. The parasitoid complex structure and size differed with locality. The number of native primary parasitoid species tended to increase toward lower latitudes. The dominant parasitoid was T. (S.) beneficus in both localities, but the degree of dominancy differed with locality. The parasitism rate was not different between localities, nor did it correlate with the number of parasitoid species at each sampling site. T. (S.) beneficus suffered high mortality during its mature larval stage. However, the mortality showed no significant relationship with initial density of mature larvae in Miyagi, whereas it was negatively correlated in Okayama. Hyperparasitism by facultative hyperparasitoids suffered an inverse densitydependent mortality to T. (S.) beneficus populations in Okayama, whereas in Miyagi the level was low and had little effect. Thus, it was predicted that populations of T. (S.) sinensis, which is closely related to beneficus, should take a long time to increase when introduced into Okayama because of the inverse density-dependent effect of facultative hyperparasitoids, but not in Miyagi.View full abstractDownload PDF (1737K) -
Yukio SHIMOJI, Tsuguo KOHAMA1994 Volume 38 Issue 1 Pages 43-46
Published: February 25, 1994
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSThe oviposition behavior of the West Indian Sweet Potato Weevil, Euscepes postfasciatus FAIRMIRE was observed in the laboratory. Oviposition behaviors were composed of searching for an egg-laying site, resting, excavating an egg-laying hole with mouthparts, ovipositing into the hole, lidding the egg-laying hole with feces, and resting after ovipositing. The size of the egg, features of the egg-laying hole and the fecal lid were also noted.View full abstractDownload PDF (538K) -
Atsushi MOCHIZUKI1994 Volume 38 Issue 1 Pages 46-49
Published: February 25, 1994
Released on J-STAGE: February 12, 2009
JOURNAL FREE ACCESSDownload PDF (562K)
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