Abstract
Some experiments were conducted to investigate the effects of the chemosterilant, hempa, on the biology of the rice weevil, Sitophilus oryzae L., and the transmission of the lethal factors in the progeny. One to three days old adult males were fed on the wheat grains treated with concentrations of 0.0625, 0.125, 0.25, and $0.5\%$ of hempa water solution. The effects of the treatment on the mortality, longevity, and the performance of oviposition were examined for the Pl generation, and the hatchability and mortality in the postembryonic development were also tested in the $F_1,\;F_2,\;BC_1,\;F_3,\;and\;BC_2$ generations to analyze the inheritance of the lethal factors. The results obtained were summarized as follows. (1) The average longevity of the treated males were ranged from 26.6 to 30.4 days, and indicated no statistical differences. (2) The mortality of the treated males were ranged between $3.3\%\;and\;13.3\%$ and showed no statistical significance. (3) The overall mean number of eggs laid by a female mated to a treated male with concentrations of 0.0625, 0.125, 0.26 and $0.5\%$ were 3.78, 4.05, 3.75 and 3.61 for the respective treatments, and they were not differ significantly from those of control which were 3.60 per female per 3 day period. The unmated female laid 1.91 in the same period, and significantly differ from those in other experimental groups. (4) The overall mean hatchability of the eggs laid by the females mated with males that had been treated with various concentrations of hempa were 86.82, 64.77, 53.47, 40.33 and $24.78\%$ for the respective concentrations of 0, 0.0625, 0.125, 0.25 and $0.5\%$. The hatchability decreased with the increasing concentrations. (5) The minimum hatchabilities were obtained from the eggs laid in the period of 10-12 days after treatment, then the hatchability increased showing some recovery. The recovery seemed to be very much delayed for the males which had been treated with the greater concentrations. Such a difference in hatchability might be related with the sensitivity of the developmental stages of the sperms, and broader spectrum in the stages and severer effects seemed to be associated with the increased concentrations. (6) The overall mean of larval mortality in the $F_l$ generation were 6.55, 17.89, 27.40, 35.42 and $52.17\%$ for the respective concentrations of 0,0.0625, 0.125,0.25 and $0.5\%$. And there was a tendency to increase in the mortality with the increase of concentrations. (7) The correlation coefficients between per cent sterile eggs and larval mortality for the experimental plots of 0.125, 0.25 and $0.5\%$ treatments showed r=+0.83 and +0.85, respectively, and it seemed to be close correlation between the lethal effects on the embryonic and post-embryonic developments. (8) Since the $SC_{50}$ of the sterile eggs was $0.133\%$ and $SC_{50}$ of the larval mortality was $0.565\%$, it was considered that tile lethal factors expressed more in the egg stages than the larval stages. (9) The ratio of female to male in the $F_l$ adults showed 100 : 125, 100 : 108 and 100 : 124 for the plots of 0.125, 0.25 and $0.5\%$ treatments, respectively. And it n·as considered that the sex ratio distortions might occur with the higher concentrations. (10) When the F, males originated 1.on the eggs had been laid by p, in the period of 16-18 days after treatment, were crossed to normal females $(BC_1)$ and made sib matings $(F_2)$, the per cent sterile eggs of the $BC_1$ generation were 13.88 and $33.04\%$ , and were 31.01 and $38.73\%$ for the $F_2$generation with the plots of 0.0625 and $0.125\%$ treatment, respectively. And these seemed to be a results of the $F_1$ individuals are carrying some chromosomal aberrations (11) The larval mortality was the highest in the $F_2$ plot and followed the female backcross plot, and the least in the male backcrosses. (12) The proportions of 1st and 2nd instar larvae among the larval development at tile 17th day after oviposition were 10.98, 27.26, 32.98 and $15.73\%$ in the normal female $\times$ normal male, $F_1$ female$\times$normal male, normal $female \;\times F_1$ male and $female \;\times F_1$ male plots, respectively. It was considered that the larval development might be delayed by the treatment in the 2nd generation. (13) Per cent larval mortality and sterile eggs were greater in the $F_2$ sib mating plots $(F_3)$ than both of $F_2$ backcrosses. Therefore, it seemed that some of the recessive lethal mutations might affect in the further generations. (14) The sterility, induced by the treatment of chemosterilant, hempa, was considered as the result of the dominant lethal mutations due to chromosomal aberrations such as translocation and/or deletion. The effects of these lethal factors seemed to be inherited tip to 3rd generation after treatment.
본 실험은 Hempa 처리가 쌀바구미 (Sitophilus oryzae L.)에 미치는 생물학적 영향과 부분불임성의 유전성에 미치는 영향을 조사하기 위하여 우화후 1-3일된 숫컷을 $0.0625\%,\;0.125\%,\;0.25\%,$ 및 $0.5\%$의 Hempa로 처리된 소맥에서 2일간 섭식처리하여 당대의 치사율, 수명 및 산란수에 미치는 영향을 조사하고 $F_l,\;F_2,\;BC_1,\;F_3\;BC_2$ 세대에 미치는 처리효과를 조사하여 다음과 같은 결과를 얻었다. (1) 처리웅충의 평균수명은 대조구에 비하여 차가 없었으며 당대 치사율도 $0.5\%$ 처리시 보정 치사율은 $7.07\%$로 유의차가 없었다. (2) 처리웅충과 교배된 정상 자충의 3일간 평균 산란수는 무처리구 3.60에 비하며 $0.0625\%,\;0.125\%,\;0.25\%,\;0.5\%$구에서 각각 3.78, 4.05, 3.75 및 3.61개로 유의차가 없었으며 비교배자충 구에서는 1.91로 현저한 산란수의 감소를 보였다. (3) 처리웅충과 무처리자충의 교배에서 얻은 $F_l$대의 처리후 27일간 총평균 부화율은 대조구 $86.82\%$에 대하여 $0.0625\%,\;0.125\%,\;0.25\%,\;0.5\%$구에서 각각 $64.77\%,\;53.47\%,\;40.33\%,\;24.78\%$로 처리농도의 증가에 따라 부화율이 감소되었다. (4) 처리후 산란 시기별로 산하된 란의 부화율은 모든 처리구에서 처리후 10-12일까지는 부화율이 감소하다가 그후 다시 증가하는 회복현상을 보였다. (5) 고농도 처리구인 $0.5\%$구에서는 처리후 1-3일에 산하된 란의 부화율이 낮았고 10-12일 이후에도 회복의 속도가 느렸다. 이와같은 현상은 배우자 형성 과정에서 영향을 받는 시기의 범위가 넓기 때문이라고 생각되었다. (6) 유충기 치사율은 대조구 $6.55\%$에 비하여 $0.0635\%,\;0.125\%,\;0.25\%,\;0.5\%$구에서 각각 $17.89\%,\;27.40\%,\;35.43\%,\;52.17\%$로 처리농도의 증가에 따라 치사율의 증가를 보였다. (7) 난기 치사율과 유충기 치사율의 관계는 $0.125,\;0.25,\;0.5\%$ 처리구에서 상관계수가 각각 r=+0.89, +0.83 및 +0.85로 난기 치사와 유충기 치사는 동일형의 영향임을 알 수 있었다. (8) 치사인자 발현에 대한 난기와 유충기의 감수성은 각각 $SC_{50}=0.133\%$ 및 $LC_{50}=0.565\%$초 난기가 유충기보다 감수성이 쳤다. 또한 미우화에 미치는 영향은 이들 둘의 공동작용의 결과임으로 $LC_{50}=0.09\%$로 더욱 감수성이 컸다. (9) $F_1$대의 우화 성충은 $0.125\%,\;0.25\%\;,\;0.5\%$ 처리구에서 암컷대 숫컷의 비율이 100 : 125, 100 : 108 및 100 : 124로 숫컷의 출현빈도가 높은 듯 하였으나 우화 개체수가 적은 관계로 통계적인 유의성은 없었다. (10) $P_1$이 처리후 16-18일에 산하한 난에서 우화한 $F_l$ 웅충을 무처리 자충과 교배하였을 때 $0.0625\%$구에서는 $13.88\%,\;0.125\%$ 구에서는 $33.04\%$의 난기 치사율을 나타내었고 $F_2$도 각각 $31.01\%$와 $38.73\%$의 치사율을 나타내고 있어 염색체 이상의 결과라고 생각되었다. (11) $F_2$ 세대의 유충기 치사율은 자충 퇴교배구가 웅충 퇴교배구 보다 높았고 $F_l$ 형매교배에서 가장 높았다. (12) $F_2$ 및 $BC_1$ 세대의 유충발육은 산난후 제17일에 1-2영충이 대조구 $10.98\%$에 비해 자충 퇴교배구, 웅충 퇴교배구 및 $F_2$구에서 각각 $7.26\%,\;32.98\%$ 및 $15.73\%$로 분화의 지연작용을 나타내는 듯하였다. (13) $F_3$ 세대에서도 난기 및 유충기 치사율이 형매교배구가 퇴교배구 보다 높았다. 이는 열성치사인자가 영향한 때문이라고 생각한다. (14) Hempa 처리에 의하여 유기된 불임은 주로 전좌나 결실과 같은 염색체 이상로 유기되는 우성치사돌연변이에 기인된 것이라고 생각되었으며 이들 인자의 영향은 처리 후 제3세대에까지 전달됨을 알 수 있었다.