Susceptibility of field and laboratory strains of pink and spiny cotton bollworms larvae to different insecticides | ||
| Journal of Pest Control and Environmental Sciences | ||
| Volume 15, Issue 1, June 2007, Pages 87-100 PDF (200.35 K) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/jpces.2007.459651 | ||
| Authors | ||
| A. A. Ismail* 1; M. A. Salama1; S. A. Hamed2; S. A. Aref3 | ||
| 1Pesticides Department, Fac. of Agric. Kafr-ElSheikh Univ., Egypt | ||
| 2Pesticides Department, Fac. of Agric., Tanta Univ., Egypt | ||
| 3Protection Research Institute, Agric. Res. Center, Giza Dokki, Egypt. | ||
| Abstract | ||
| The susceptibility of field and laboratory strains of pink (Pectinophora gossypiella) and spiny (Earias insulana) cotton bollworms larvae to three different insecticides was studied. The significant differences between insecticidal-treatments and control are due to the high mortality of treated larvae before entering the bolls. Based on the LC50 values, it is quite clear that cypermethrin was the most toxic insecticide against both strains, followed by profenofos and thiodicarb in a descending order. The LC50 values in case of the laboratory strain are: 17, 90 and 300 ppm for cypermethrin, profenofos and thiodicarb, respectively. Based on the toxicity index values, it is apparent that cypermethrin is the most potent compound against the 2nd larval instar of both strains followed by profenofos and thiodicarb with toxicity index values of 100, 18.9 and 5.7, respectively (in case of lab strain) and 100, 16.8 and 6.9, respectively (in case of field strain). Based on the tolerance levels, the data showed that no single case of tolerance was observed since the calculated tolerance values are: 1.53, 1.72 and 1.25 for cypermethrin, profenofos and thiodicarb, respectively. The data also showed that no change in the reactions of the lab and field strains to the three tested insecticides occurred as their degree of homogeneity (D.H.) values are equal to 0.96. 0.95 and 1.03 (which is almost equal to 1.0). Cypermethrin was the most toxic insecticide against both laboratory and field strains followed by profenofos and thiodicarb in a descending order. The data revealed that cypermethrin is the most toxic compound against both second and fourth instars larvae followed by profenofos and thiodicarb. Based on the initial mortality cypermethrin is more toxic against both bollworms followed by profenofos while thiodicarb is the least toxic compound in this respect. Based on the residual percent mortality, the data confirmed the previous trend of result. In other words, cypermethrin has relatively long residual action followed by profenofos and thiodicarb. In term of figures, in case of pink bollworm, their percentages mortality is, 66.77, 63.72 and 33.39, respectively. The corresponding values, in case of spiny bollworm, are: 57.00, 55.54 and 34.88, respectively. Based on the residual toxicity, one could figure out that, apart of thiodicarb, the spiny bollworm showed little tolerant towards both profenofos and cypermethrin in comparison with the pink bollworm. | ||
| Keywords | ||
| Cotton bollworms; Susceptibility; Pectinophora gossypiella; Earias insulana; Insecticides; Field strain; Laboratory strain | ||
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