• Korean journal of applied entomology
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• v.49 no.4
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• pp.357-362
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• 2010

Soybean seed injury was analyzed in the experiments in which the bean bug, Riptortus pedestris(Hemiptera: Alydidae), was released into screen-caged pots containing full seed stage(R6) of soybean. When the different stages of insects, from the 3rd instar nymphs to adults, were released into pots during 8 days in soybean R6 stage, soybean seeds with injury marks (B-type seeds) increased. The weight reduction ratio in B-type seeds was highest in the injury by the 5th instar nymphs, while the daily-produced number ratio of B-type seeds was small in the treatment. In the injury by the different number of adult released into pots, 4, 8, 16 adults caused a significant increase of B-type seeds, while 16 adults caused the significant increase of the deformed (C-type) seeds. In the injury by the different release period of adults, the total number of pods was not significantly different among treatments, while the total seed number harvested was significantly small in the release for 48 days. The release for 8 and 16 days caused a significant increase of B-type seeds, while the release for 48 days caused the increase of C-type seeds. The results indicated that injury of soybean R6 stage by the bean bug produced soybean seeds with distinct injury marks at relatively low density and during short term attack period, while it produced deformed seeds at high density and during long attack period.

• Korean journal of applied entomology
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• v.33 no.2
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• pp.114-121
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• 1994

Population densities of intermediate nymphs and egg saw of Matsucoccus thunbergianae, a major insect pest of Pinus thunbergiona in southern coastal area of Korean peninsula, were est~mated. Tree samples of ca. 10cm D.B.H. were collected from old infestation area and newly invaded area. The numben of plimaly branches per tree were not significantly different by the locality, but those of secondaly and smaller branches were smaller in old infestation area The numbers of intermediate nymphs per tree in old infestation area and in newly invaded area were 10.8 and 13.1 times more than those on the trunk, respectively Approximately between 4, 200 and 208, 500 nymphs per tree were estimated. Men secondaw and smaller bmnch samples collected from the basal part of middle crown height, or from the central or the basal part of lower crown height, the number of samples required for the emr range of 20% were 21 and 11 far 10-20cm and 20-3 crn long branches, respectively. Approx~mately 63.6% of egg sacs of the whole tree were on the trunk. The node/intemode bearing the largest branch had the highest egg sac density; including that, four adjacent nodes/intemodes had ca. 37% of egg saw on the trunk.

• Korean journal of applied entomology
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• v.49 no.4
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• pp.305-312
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• 2010

The developmental time of immature stages of Paromius exiguus (Distant) was investigated at nine constant temperatures (15, 17.5, 20, 22.5, 25, 27.5, 30, 32.5, $35{\pm}1^{\circ}C$), 20-30% RH, and a photoperiod of 14:10h (L:D). Eggs did not develop at $15^{\circ}C$, and their developmental time decreased with increasing temperatures. Its developmental time was longest at $17.5^{\circ}C$ (28.2 days) and shortest at $35^{\circ}C$ (5.9 days). The first nymphs failed to reach the next nymphal stage at 17.5 and $35^{\circ}C$. Nymphal developmental time decreased with increasing temperatures between $20^{\circ}C$ and $32.5^{\circ}C$, and developmental rate was decreased at temperatures above $30^{\circ}C$ in all stages except for the fourth nymphal stage. The relationship between developmental rate and temperature fit a linear model and three nonlinear models (Briere 1, Lactin 2, and Logan 6). The lower threshold temperature of egg and total nymphal stage was $l3.8^{\circ}C$ and $15.3^{\circ}C$, respectively. The thermal constant required to reach complete egg and the total nymphal stage was 109.9 and 312.5DD, respectively. The Logan-6 model was best fitted ($r^2$=0.94-0.99), among three nonlinear models. The distribution of completion of each development stage was well described by the 3-parameter Weibull function ($r^2$=0.91-0.99).