Affectivity of Spodoptera littoralis nucleopolyhedrovirus (SpliNPV) against first and second instar larvae of the cotton leafworm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae)

Abstract

Affectivity ofPreliminary bioassays were conducted to determine the virus activity against the 1 st and 2 nd instar larvae of the cotton leafworm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae). First instar larvae were more susceptible to the virus than the second instar larvae. Mortality response of the larvae was greater at the highest concentration of the virus than at lowest concentrations. The lethal concentration that killed 95% of the tested larvae (LC95%) was 2.32 x 10 , 2 x 10 4 , 2 x 10 5 and 2 x 10 6 PIB/ml). However, second instar (2 nd ) larvae were less susceptible to the virus than the first instar larvae with the mortality rate of 0, 4, 9.39, 25.33, 43.24, and 71.63%, for the same tested concentrations, respectively. In control treatment, no mortality was recorded. The high concentration levels caused a high rate of mortality. The same trend of mortality is similar to those found by other studies.

Molecular detection and pathogenicity of a nucleopolyhedrovirus isolated from looper caterpillar (Hyposidra talaca), a tea pest

“…Although this relation between the rate of change in mortality with the lessening dosage is not directly proportional, as the dose decreases ten times the mortality rate is decreased well less than ten times. Previous studies also support this observation (Jankevica and Zarins 1999; Sajap et al 2000; Sethuraman and Narayanan 2010; Mukhopadhyay et al 2011; Sutanto et al 2014). However, the regression result in Table 2 shows that a positive correlation exists between mortality and dosage, as all the slope values are positive and infinitesimal Chi squares signify that there is a good linear fit.…”

“…Stiles and Himmerich (1998) also observed higher LC 50 of Ac MNPV against second instar Heliothis zea (i.e., 6.38 × 10 5  POBs/ml). Second instar larvae of Spodoptera littoralis were also highly susceptible to the SpliMNPV at the higher concentration of 2 × 10 6  POBs/ml, which caused a high rate of mortality than the lower concentration (Sutanto et al 2014). …”

Impairment of Development and Reproductivity of the Egyptian cotton leafworm Spodoptera littoralis Boisduval (Noctuidae: Lepidoptera) by Cycloheximide.

“…The caterpillars feed mainly on leaves, stems and also can seriously retard growth or reduce production of the cotton crop. However, during heavy infestation they can penetrate flowers and bolls (Sutanto et al, 2014). To control this pest, several types of conventional insecticides have been used over the last five decades.…”