Susceptibility of field and laboratory strains of Cotton leafworm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) to spinosad pesticide under laboratory conditions

Abstract

Ahmed M.A.I., Temerak S.A.H., Abdel-Galil F.A.-K., Manna S.H.M. (2016): Susceptibility of field and laboratory strains of Cotton leafworm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) to spinosad pesticide under laboratory conditions. Plant Protect. Sci., 52: 128-133.The susceptibility of field and laboratory strains against all instars larvae of S. littoralis to spinosad pesticide after a 24-and 48-h exposure and under laboratory conditions was investigated. As a result against 1 st instar larvae, the LC 50 values after 24 h were 12 and 0.275 µg/ml for laboratory and field strain, respectively. In addition, the resistance ratio (RR) of 1 st instar was 43.64-fold. In this interim, the 48 h LC 50 values were 8.7 and 0.18 µg/ml for laboratory and field strain, respectively and the RR was 48.33-fold, which revealed the field strain was more susceptible to spinosad than the laboratory strain. Distinctly similar trend was shown for later instar larvae stages. For instance, in 6 th instar larvae, the LC 50 values after a 24-h exposure to spinosad were 1100 and 105 µg/ml for the laboratory and field strain, respectively, and the RR value was 10.48-fold. Furthermore, after a 48-h exposure, the LC 50 values for laboratory and field strains were 500 and 42 µg/ml, respectively, with RR value being 11.90-fold. On the other hand, according to relative tolerance values, the 6 th instar larvae were the most tolerant instar of all the instars tested. The susceptibility of 6 th , 5 th , and 4 th instar larvae was comparable and significantly lower than that of 3 rd , 2 nd , and 1 st instar larvae. However, the 1 st instar was the least tolerant. The results implied that spinosad may play a potential role in the control of S. littoralis and, therefore, it is considered a promising tool in integrated pest management program to control Cotton leafworm which is becoming resistant to conventional pesticides in Egypt.

Pesticide contamination of milkweeds across the agricultural, urban, and open spaces of low elevation Northern California

“…It is not clear how an LD 50 of one compound over 36 hours compares with an LD 50 of a different compound over 48 hours, and what either of these can tell us about risk in the field. A larval monarch will consume a plant for much longer than 48 hours, and generally longer exposure times will decrease survival (Abivardi et al, 1999; Yue et al, 2003; Wang et al, 2009, 2013; Nasr et al, 2010; Rehan and Freed, 2015; Ahmed et al, 2016; Liu et al, 2018b). Thus, considering shorter exposure times is likely to be a conservative approach which underestimates risk.…”

Enhancing the Toxicity of Cypermethrin and Spinosad against Spodoptera littoralis (Lepidoptera: Noctuidae) by Inhibition of Detoxification Enzymes

“…In addition, SPD may have a potential role in controlling S. littoralis . Therefore, it is considered a promising tool in integrated pest management programs for controlling cotton leafworm under laboratory conditions [ 27 ]. Rotation of SPD with none and negative cross-resistance can effectively control S. littoralis [ 4 ].…”

An Experimental Study of Certain Neonicotinoid Insecticides on the Incidence of Early Infestation of the Spiny and the American Bollworms, Growth and Lint Yield Characteristics of Cotton Plants

“…Because of their systematic characteristic, they are applied against soil-living pests and seed as well as foliar treatments (Magalhaes et al 2009;Lanka et al 2013). In recent years, the use of systemic insecticide as seed treatments is considered one of the most effective compounds against sucking insects such as aphid, whiteflies, thrips and many coleopterans as well as some lepidopteran species (Yue et al 2003;Ahmad et al 2013;Ahmed 2014) . In general, seed treatments require much less active ingredient to control pests than traditional application methods, this will led to reduce exposure of the insecticide to the agriculture workers, environment and natural enemies (Nault et al 2004;Younis et al 2007).…”

“…Moreover, only few data are available on the lethal and sub-lethal effects of insecticides belonging to neonicotinoids on the lepidopteran insects e.g. Helicoverpa armigera (Ahmad et al 2013) and Spodoptera littoralis (Ahmed, 2014) under laboratory conditions; and Ostrinia nubilalis (Yue et al 2003) under field conditions. That, emphasis the need of advanced research works to through more lights on the potential toxic effect of two insecticides belonging to neonicotinoids i.e., (imidacloprid and thiamethoxam) against two lepidopteran insect species under field conditions.…”