Pest Control Research

Behavioral responses to various inorganic chlorides and zinc compounds in rats were determined by the gradual two-bottle preference method. In the concentrations beyond the threshold for discrimination, rats had a rejective response to these test compounds. Two series of taste stimulating effects of the test compounds (epressed as a reciprocal of the threshold for discrimination) was obtained in the order of larger values (M) as follows: HgCl₂>ZnCl₂>PbCl₂≧CuCl₂>NiCl₂>BaCl₂>FeCl₃>SnCl₂>LiCl>AlCl₃>MgCl₂
>CaCl₂>SrCl₂>CsCl>KCl>NH₄Cl>NaCl, and ZnCl₂≧ZnSO₄≧Zn(NO₃)₂≧
Zn(CHCOO)₂. Neural responses of the chorda tympani nerve to these inorganic chlorides in rats were datermined and on the basis of the magnitude of initial phase of the integrated responses, a series of gustatory effectiveness of these inorganic chlorides was different from that above mentioned. Accordingly, an intimate relationship between these two series was not obtained.

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Room temperature affected the frequency of delivery of the roof rat, Rattus rattus. The frequency in February was the lowest and 12.5% which was about one third of that in May or July. Regression of the frequency (%) on a mean room temperature (℃) of each month was Y=1.0X-5.9 (r=0.69. p<0.01).
The rat in urban buildings maintains probably a high frequency of delivery owing to such a mild room temperature.

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The head width of hidernating cockroaches, Asiablatta kyotoensis Asahina, in an unheated room divided nymphs into two groups, young nymphs (2nd-4th instars) and older nymphs (7th-8th or final instars and excessively molted instars). The older nymphs emerged into adults in early summer, producing several oothecae before dying in fall. The younger nymphs overwintered again in older stages. New nymphs hatching before mid-summer developed into final or penultimate instar stage before overwintering, while those hatching in fall overwintered in 2nd-4th instars. The formation of two phases in hibernating nymphs indicates the existence of timing mechanisms such as diapause.

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Two kinds of pheromone traps,Biolure^® for pyralid moths and New Serrico^® for cigarette beetles, were used in a factory producing animal foods and three ordinary houses in Shizuoka Prefecture, Japan, from spring through the fall in 1992.

Three species of pyralid moths were caught in high numbers in the factory. The most abundant was Ephestia kueniella, followed by E. cautella and then Plodia interpunctella. In the three houses, however, only P. interpunctella moths were caught abundantly ; seven E. cautella moths and no E. kueniella moths.

Many cigarette beetles, Lasioderma serricorne, were caught in the factory from May to October (inclusive) with the first peak in July and the second in October. Each of the three houses showed only one peak late in August or early in September, no or very few individuals in the other months.

No breeding site for the species was found in the three houses. One of the houses that had an especially high density of the insects during the peaks had poorer seailing conditions, having so many voids and crevices in the wall as well as ill―fitting doors and windows.

These facts suggest that the insects may invade consumers' houses from outdoors or nearby fascilties, causing insects contamination of foods at home.

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