兩種蟲生線蟲Steinernema abbasi及Steinernema carpocapsae對德國蜚蠊之致病評估

Abstract

Pathogenicity of the entomopathogenic nematodes, Steinernema abbasi and S. carpocapsae, against the German cockroach, Blattella germanica, was conducted in this study. Adult males, females, and last nymphs of B. germanica were inoculated with 2,654 IJs/cm2 S. abbasi and S. carpocapsae, respectively, at 25 ± 2°C. The LT50 values against these three stages treated with S. abbasi were 77.7, 44.4, and 116.2 h, respectively, whereas those treated with S. scarpocapsae were 29.4, 22.2, and 43.2 h, respectively. These results showed that the LT50 values of S. carpocapsae were significantly shorter than those of S. abbasi to B. germanica, and that the LT50 values of two entomopathogenic nematodes to adult females were shorter than males and last stage nymphs, suggesting that adult females was more sensitive to nematodes than others. After storing for 0, 1, and 2 months, the mortalities of adult males caused by S. abbasi were 63, 16.7, and 5%, respectively, whereas those caused by S. carpocapsae were 100, 80, and 66.7%, respectively, at 4th day post-inoculation. The pathogenicity and persistance of S. carpocapsae were better than S. abbasi at 25 ± 2°C. Dog foods and cockroach feces extracts were placed in nematode traps for evaluating the killing activity of these two nematodes. The cumulative mortality of B. germanica treated with S. abbasi traps for 4 days was 0.8 - 4.2%, while that treated with S. carpocapsae was 55.6 – 76.7%. In contact tests, S. carpocapsae caused higher mortality (23.8 – 46.3%) than S. abbasi (1.25 – 15%) after incubation for 4 days, revealing that S. carpocapsae could infect B. germanica in 10 seconds and caused 23.8% mortality, suggesting that entomopathogenic nematodes can effectively infect B. germanica in few seconds. These results showed that the nematode traps were useful for killing B. germanica, especially using S. carpocapsae.