3种光敏剂毒杀白纹伊蚊幼虫的实验室与野外应用研究

Study on the killing efficacy of three photosensitizers to Aedes albopictus larvae in the laboratory and the field

目的研究光敏剂琥红(RB)、赤鲜红B、α-三噻吩对实验室饲养及野外白纹伊蚊4龄幼虫的杀灭效应。方法分别在实验室和野外条件下,计数不同药物浓度、不同光源照射和照射强度、不同处理时间的RB、赤鲜红B、α-三噻吩作用后白纹伊蚊4龄幼虫的死亡数,分析其影响杀蚊幼虫的实验参数。用组织化学的方法,研究其毒理机制。结果RB、赤鲜红B、α-三噻吩无暗毒性。用固定光源100W日光灯照射,照射强度为320×102lx,时间为6h;RB药物浓度分别为10、25μg/ml,赤鲜红B药物浓度分别为100、150μg/ml,皆可达到100%杀灭白纹伊蚊4龄幼虫的效果。用中低强度的太阳光照射5h,α-三噻吩药物浓度为1μg/ml,亦可达到100%杀灭白纹伊蚊4龄幼虫的效果。初步将赤鲜红B、α-三噻吩分别应用于野外不清澈和清澈自然水体内控制白纹伊蚊幼虫,赤鲜红B、α-三噻吩在野外不清澈水体内的杀虫率分别为46%和49%,而在清澈自然水体内的杀虫率分别为67%和89%;但当持续强度太阳照射,α-三噻吩在前2种水体内杀虫率皆可达到98%。组织化学试验结果显示:用RB、赤鲜红B、α-三噻吩处理的白纹伊蚊4龄幼虫,经光毒作用后,蚊中肠绒毛消失,细胞肿胀,细胞核消失。脂肪体在表皮下广泛分布,马氏管外形不规则及管腔狭窄等病理变化。结论RB、赤鲜红B、α-三噻吩3种光敏剂皆是高效、实用的光敏化杀虫剂。

Objective To assess the killing efficacy of three photosensitizers such as rose bengal（RB）, erythrosin B and α-terthiophe to the fourth-instar larvae of Aedes albopictus in the laboratory and the field. Methods The number of dead larvae was recorded after application of RB, erythrosin B and α-terthiophen at different illumination conditions, and experimental parameters affecting photoinsecticidal was analyzed. The toxicity mechanism of RB, erythrosin B and α-terthiophen was studied by hislochemistry metllod. Results RB, erythrosin B and α-terthiophen showed less activity in dark . The killing effect to larvae could reach 100% using 10 or 25 μg/ml RB and 100 or 150 μg/ml erythrosin B after exposed to 320 × 10^2 lx of light intensity generated by daylight lamp （100 W） for 6 h. The killing effect of α-terthiophen also achieved 100% at the concentration of 1 μg/ml after exposure to moderate or low intensity sunlight for 5 h. Erythrosin B and α-terthiophen was applied to control Ae.albopictus larvae in the clear water or muddy water of the field respectively. The result showed the killing rates of RB and α-tcrthiophen were 46% and 49% in the muddy water body, and 67% and 89% in the clear water body. However, that of α-terthiophen reached 98% in the above mentioned water body after continuously exposed to strong sunlight. Severe pathological damage of larvae caused by RB, erythrosin B and α-terthiophen were observed with optical microscopic. The damage were as follows： villus of midgut disappeared, midgut cells swell and cell nucleus disappeared. Fat body widely distributed under the epidermis and the shape of malpighian tubes was abnormal and its lumens narrowed. Conclusion RB, erythrosin B and α-terthiophen are high-efficiency and applied photo-insecticides.