Keizi Kiritani

Quantitative evaluation of predation by spiders on the green rice leafhopper,Nephotettix cincticeps Uhler, by a sight-count method

A sight-count method for evaluation of predation by spiders on the green rice leafhopper,Nephotettix cincticeps was proposed and its applicability was tested under natural conditions. The number (n) of leafhoppers preyed on by spiders per rice hill per day was estimated by the formula: (1)

Co-existence of the two related stink bugsNezara viridula andN. Antennata under natural conditions

n = \frac{{F \cdot C}}{P}

An analysis of the predator-prey system in the paddy field

whereF is the frequency of predation observed per hill:P is given by dividing the time spent feeding on prey by 24 hours; andC refers to the total amount of feeding activity expressed in terms of the activity during the standard time interval. The total number (N) of prey attacked during the specified period can be given as follows: (2)

Studies on the adult polymorphism in the southern green stink bug,Nezara viridula (hemiptera: Pentatomidae)

N = \sum \left\{ {(n_i + n_{i + 1} ) \times \left( \begin{gathered} census interval between \hfill \\ times i and i + 1 \hfill \\ \end{gathered} \right) \times \tfrac{1}{2}} \right\}

A method for estimating natural survival rate and mean fecundity of an adult insect population by dissecting the female reproductive organs

With this method, the role of paddy-inhabiting spiders,Lycosa pseudoannulata, Oedothorax insecticeps, Tetragnatha spp, andEnoplognatha japonica, as predator ofN. cincticeps was evaluated with reference to life tables of the prey. The advantages and limitation of the sight-count method were discussed as compared with other methods so far proposed.

A preliminary model to simulate the effect of insecticides on a spider-leafhopper system in the paddy field

An application ofHokyo andKiritanis method (1967) was attempted to estimate the stage specific survival rates of the population with overlapping stages. This method can be written as follows assuming a constant daily survival rate (K) throughout the life: