Two different Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) nucleopolyhedrovirus (SpliNPV) isolates were obtained from natural infected S. littoralis larvae in Egypt. The phylogenetic analysis of the partial nucleotide sequence of the polyhedrin gene (polh) showed that both isolates, Spli-6 and Spli-7, were closed and had a common ancestor with S. littoralis NPV isolate 1263 polyhedrin gene, partial coding sequence with accession number AGE90003.1 that belongs to group II NPVs. This indicates that the natural host of Spli-6 and Spli-7 must be S. littoralis. The virulence of these isolates was tested against S. littoralis larvae in a laboratory. The LC50 against 1st instar larvae was significantly different, 3 × 104 OBs/ml and 9.5 × 104 OBs/ml for Spli-6 and Spli-7, respectively. However, the LC50 for the mixed infection of both isolates was 3.9 × 104 OBs/ml. On the other hand, the ST50 was 96 h for both isolates, while it was 120 h for the mixed infection, which was higher than that observed of each single isolate. Upon digestion of viral DNA with ScaI endonuclease, the restriction profile showed one more fragment of about ~ 25 kbp and 3 fragments of about ~ 19, ~ 5.8, and ~ 5.3 kbp in Spli-7 isolate compared to Spli-6 as well as the reference strain SpliNPV-AN1956. The differences in the fragment size and number suggest the existence of genotypic variants between both isolates. Spli-6 and Spli-7 proved to possess promising insecticidal properties for the development of virus-based biopesticide for the control of S. littoralis.

中文翻译：

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评价两种病毒分离物作为对埃及棉叶蠕虫斜纹夜蛾（Boodd。）的潜在生物防治剂（鳞翅目：夜蛾科）

从埃及自然感染的S. littoralis幼虫中获得了两种不同的斜纹夜蛾（Boidd。）（鳞翅目：夜蛾科）核多角体病毒（SpliNPV）分离株。对多角体蛋白基因（polh）的部分核苷酸序列的系统进化分析表明，两个分离株Spli-6和Spli-7都是封闭的，并且与滨海链球菌NPV分离株1263多角体蛋白基因具有共同的祖先，部分编码序列有登录号。属于第II组NPV的编号AGE90003.1。这表明Spli-6和Spli-7的自然宿主必须是滨海链球菌。在实验室中对这些分离株的毒力进行了抗沿海链球菌幼虫的测试。针对第一龄幼虫的LC50显着不同，Spli-6和Spli-7分别为3×104 OBs / ml和9.5×104 OBs / ml。然而，两种分离株混合感染的LC50为3.9×104 OBs / ml。另一方面，两种分离株的ST50为96 h，而混合感染的ST50为120 h，高于每个分离株的ST50。用ScaI核酸内切酶消化病毒DNA后，与Spli-6和Spli-6相比，限制性酶切图谱显示Spli-7分离物中还有一个约25kbp的片段和3个约19、5.8和5.3kbp的片段。参考菌株SpliNPV-AN1956。片段大小和数量上的差异表明两个分离株之间均存在基因型变异。Spli-6和Spli-7被证明具有开发基于病毒的生物农药以控制滨海链球菌的有希望的杀虫特性。混合感染时间为120小时，高于每个单独的菌株。用ScaI核酸内切酶消化病毒DNA后，与Spli-6和Spli-6相比，限制性酶切图谱显示Spli-7分离物中还有一个约25kbp的片段和3个约19、5.8和5.3kbp的片段。参考菌株SpliNPV-AN1956。片段大小和数量上的差异表明两个分离株之间均存在基因型变异。Spli-6和Spli-7被证明具有开发基于病毒的生物农药以控制滨海链球菌的有希望的杀虫特性。混合感染时间为120小时，高于每个单独的菌株。用ScaI核酸内切酶消化病毒DNA后，与Spli-6和Spli-6相比，限制性酶切图谱显示Spli-7分离物中还有一个约25kbp的片段和3个约19、5.8和5.3kbp的片段。参考菌株SpliNPV-AN1956。片段大小和数量上的差异表明两个分离株之间均存在基因型变异。Spli-6和Spli-7被证明具有开发基于病毒的生物农药以控制滨海链球菌的有希望的杀虫特性。与Spli-6以及参考菌株SpliNPV-AN1956相比，Spli-7分离物中的〜5.3 kbp。片段大小和数量上的差异表明两个分离株之间均存在基因型变异。Spli-6和Spli-7被证明具有开发基于病毒的生物农药以控制滨海链球菌的有希望的杀虫特性。与Spli-6以及参考菌株SpliNPV-AN1956相比，Spli-7分离物中的〜5.3 kbp。片段大小和数量上的差异表明两个分离株之间均存在基因型变异。Spli-6和Spli-7被证明具有开发基于病毒的生物农药以控制滨海链球菌的有希望的杀虫特性。