The salivation and ingestion behavior of the aster leafhopper, Macrosteles fascifrons STAL on sucrose and plant substrates was recorded using the electronic measurement system developed by MCLEAN and KINSEY (1964). The salivation and ingestion activities of the leafhopper when probing into a feeding chamber filled with a 5% solution of sucrose produced two kinds of waveforms : salivation (S) and ingestion (I). These waveforms were similar to those observed with the pea aphid, Acythosiphon pisum HARRIS (MCLEAN and KINSEY, 1964, 1965. 1967). On rice plants, the leafhoppers often produced other waveforms in addition to S and I waveforms. The acitivities associated with these waveforms during leafhopper probing within rice plant tissue were not determined but it is possible that these unknown wave forms may be important in understanding in more detail, the probing and ingestion behavior of leafhoppers. These unknoen waveforms were labelled U₁, U₂ and U₃. It appears that some modification of the original aphid measurement system will be necessary in order to more precisely interpret leafhopper salivation and ingestion activities.

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The action of juvenile hormone (JH) on the accumulation and release of neurosecretory material in the cerebral neurosecretory cells of the cabbage armyworm, Mamestra brassicae, was investigated. When a juvenile hormone analogue (JHA, ZR-515) was injected into a 6-day-old last instar larva immediately followng removal of the prothoracic glands, which normally causes the release of neurosecretory material from type II cerebral neurosecretory cells (type II-NSC), release of this material was inhibited and accumulation was observed in the type II-NSC. Conversely, when JHA was injected into the larva 24 hr after removal, of the prothoracic glands, stainable neurosecretory material did not accumulate in the type II-NSC. Brains from 0-, 8-day-old last instar larvae and 1-day-old pupae cultured in vitro in medium containing JHA accumulated ceurosecretory material in the type II-NSC. While, when the effects of JHA on prothoracicotropic hormone (PTTH) release from the brains was examined by the implantation experiments, and the releasing PTTH from the brains of 0-, 6- and 8-day-old last instar larvae was really inhibited by JHA application. These results suggest that in the limited stages, JH inhibits the release of PTTH which seems to be released from the type II-NSC in M. brassicae, but may not affect the synthesis of neurosecretory material in these cells.

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DNA content in the whole body of Bombyx mori remained almost unchanges for the first 2-3 days after larval-pupal ecdysis and then decreased continuously throughout subsequent development. RNA content in the whole body decreased slightly for the first 2-3 days, increased up to day 6-7 of the development and again decreased thereafter. RNA/DNA ratio in the whole body rose constantly with an initial lag period and reached a maximum 2-3 days before adult emergence. The ratio then fell slightly. A cross relationship was observed between the loss of wet weight from the fat body and the gain in the ovary and carcass, supporting that the fat body functions as a storage tissue of reserve materials. Meconium production was more prominent in males than in females, possibly reflecting a weak demand to nitrogeneous compound for the gonad growth in the males.Both the content and the concentration of nucleic acids in several tissues changes considerably in the course of pupal-adult development, reflecting histolysis and histogenesis. The most characteristic changes were found in DNA of the degenerating silkgland and the midgut. Both the tissues in histolysis showed conspicuously high levels in DNA concentration, resulting in minima of RNA/DNA ratio, which indicates that DNA decrement was not synchronized with the decrease in tissue weight and the RNA loss in these tissues. It is suspected that such delayed decrement of DNA may be attributable to the rigidity of DNA-histone complex in the chromatin.

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The essential amino acids for the growth of insect cells in cultures were determined by the use of single amino acid-deficient media. The continuous cell lines derived from a moth, Mamestra brassicae, and from two mosquito species, Aedes aegypti and Culex molestus, were cultured in the media from which one of amino acids had been omitted. The growth rate in 8-day cultures was examined, and further continuous subculturing was conducted up to 10th passage with amino acid-deficient media. Arginine, cystine, glutamine. histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine and valine were found to be essential for the growth of all the cell lines examined. α-Alanine, β-alanine, asparagine, aspartic acid and glutamic acid seem to be non-essential for the growth of the cells. The role of glycine could not be determined.

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KNIPLING and MCGUIRE's (1966) equation describing the competition between pheromone traps and adult females for adult males was critically discussed. It was revealed that their equation could not properly deal with such competition because of the unrealistic assumptins they adopted in it. A new equation was developed in this paper, and the relationship between the number of males capatured in traps and the number of females mating was derived from it. Data from competition experiments were applied to this new equation and it was shown that it is applicable to a wide variety of trap-female competition situations.

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For practical application of synthetic sex pheromone to control Spodoptera litura, it is needed to develop a trap useful for monitoring and mass-trapping.The trap reported in this paper was a box (30 cm×25 cm×8 cm) made of polyvinyl chloride plates. The trap had two ducts (section : 3 cm×3 cm) the openings of which were attached to the perforated end walls. On the shunt end of the duct, a valve made of perforated thin plastic plate was hung to lead the males inside and to prevent their escape. The results of greenhouse tests demonstrated that the most suitable weight of the valve was 0.7 g for efficient trapping and that the optimum width of the slit between the bottom of the duct and the end of the valve was 6 mm. The captured males were killed rapidly in the trap by the heat of the sun. The desiccated dead bodies in the trap did not influence the trapping efficiency. Each trap caught about 2000 wild males from June to November in field tests.

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Susceptibility of three carbamate insecticides and secsitivity of acetylcholinesterase (A-ChE) to a carbamate in susceptible and resistant strains and their F₁, F₂ and backcross progenies of the green rice leafhopper were determined. The results suggested that the carbamate-resistance is mainly contolled by an incompletely dominant autosomal factor, and that the gene responsible for the insensitivity of AChE is probably on the same autosome. Evidence based on the results of repeated backcrosses to the susceptible strain under selection with a carbamate suggested that both the carbamate-resistance and the carbamate-insensitivity of AChE are due to the same gene. It was also considered that non-specific esterases do not play a role in carbamate-resistance.The relationships between the insensitivity of AChE and cross-resistance in the multi-resistant leafhopper was analyzed using a special strain in which the gene for the insensitivity of AChE was introduced by repeated backcrosses into the background of the susceptible strain. By comparing susceptibility to insecticides and sensitivity of AChE to inhibitors in the substrain versus the two parental strains, it was found that resistance to the carbamates propoxur, Tsumacide [○!R] (3-methylphenyl N-methylcarbamate), carbaryl, Bassa[○!R] (2-sec-butylphenyl N-methylcarbamate) and Knockbar[○!R] (3-tert-butylphenyl N-methylcarbamate) is caused mostly by the insensitivity of AChE. In contrast, resistance to carbanolate, Hydrol[○!R] (4-diallylamino-3, 5-dimethylphenyl N-methylcarbamate) and methomyl was influences little or not at all by the alteration of AChE. The altered AChE was also found to contribute a part of the resistance to organophosphates such as malathion, phenthoate, fenitrothion and Fujithion[○!R] (S-(p-chlorophenyl)O, O-dimethyl phosphorothiolate), but had no influence on the resistance to pyridafenthion, propaphos, acephate and diazinon. Diazoxon, pyridafenthion-oxon and propaphos inhibited the altered AChE of the resistant strain more strongly than the normal enzyme of the susceptible strain.

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The control threshold and the tolerable injury level for the rice leaf beetle, Oulema oryzae KUWAYAMA, an important rice insect pest in northern Japan, were studied from 1974 to 1977 in Akita, Japan.Adults of the rice leaf beetle oviposited egg-masses on rice leaves in early June, and larvae injured leaves from mid to late June. The relation between damage and rice yield was examined in experimental paddy fields. From these experiments, the tolerable injury level was set at 20% injured leaves in late June. From surveys on egg-mass density and percentage of injured leaves in various paddy fields, the control threshold was estimated at 0.5 egg-masses per hill in early June.If this control threshold is adopted in Akita Prefecture, insecticide applications for the rice leaf beetle can be reduced.

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Field and laboratory experiments were conducted to assess the validity of the theoretical model; A_t=1-exp (-α·N_A·L·P), where A_t is the percentage of rice hills infected with rice dwarf virus (RDV), α is the number of hills infected successfully by a vector per day, N_A is the total number of adults per hill that have immigrated, L is the mean longevity of the adults in the rice field and P is the percentage of infective individuals. The calculated value obtained by substituting observed values for the parameters in the model showed close agreement with the observed value for A_t. Management of RDV infection in rice fields based on the relationship between the proportion of infected hills (A_t) and the product of parameters (α·N_A·L·P) is also discussed.

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The effects of moth age on the mating behavior of the rice stem borer moth, Chilo suppressalis WALKER, were investigated. The mating frequency of same-aged pairs was low at 1 day old, reached the maximum at 2 or 3 days old, and, thereafter, decreased rapidly with age. The pattern of effects of age on mating activity was different between male and female. The female activity maintained a high level up to an age of 4 days, but thereafter, it decreased rapidly. The male activity was at a low level in newly emerged moths, attained a peak at 3 or 4 days old, and was kept rather high level until 8 or more days of age. It seems that in same-aged pairs, the low level of mating success at 1 day old was due to male activity and the rapid reduction of it after 4 days was determined by the females. The begining of mating and calling became earlier with age. These results should be considered whne the sex pheromone is applied in the field to control this insect.

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