Effects of nonsteroidal ecdysone agonist RH-5992 and chitin biosynthesis inhibitor lufenuron on Spodoptera littoralis (Boisduval, 1833)

Abstract

Abstract:Comparative studies of the effects of two compounds, tebufenozide (an ecdysone agonist) and lufenuron (an insect growth regulator inhibiting chitin synthesis), were conducted on Spodoptera littoralis (Boisduval, 1833). The compounds, orally administered, caused larval mortality proportional to the concentrations in the food source. Tebufenozide initiated precocious molting, and lufenuron, and inhibited chitin synthesis. In both cases, larvae were unable to complete the molting process and died in the old larval cuticle. Larvae contaminated by sublethal doses completed their development to adulthood. Lufenuron is more active than is tebufenozide. LD-50 for lufenuron is 0.0001ppm and for tebufenozide 0.001ppm. Topical application of the test compounds to eggs caused dose-and agedependent inhibition of embryonic development. Application of tebufenozide in the second half of embryogenesis caused precocious molting of eclosed larvae of the 1 st instar. Some morphological changes in the process of larval-pupal transformation were also observed. Tested compounds also reduced reproduction in adult individuals that had been treated by the tested compounds in the larval stage.

Effect of buprofezin on the growth, development and morphometric parameters of Spodoptera litura (Fabricius) (Order: Lepidoptera, Family: Noctuidae) adult

“…These findings could be linked with Wang and Tian (2009) and Gelbic et al (2011) who successfully tested IGRs compounds against several insect species example Spodoptera litura and S. littoralis which inhibits or prevents normal metamorphosis of immature stages to the adult stages.…”

“…Among different IGRs Buprofezin is one of the important chitin synthesis inhibitors (CSIs) that prevent chitin bio-synthesis and deposition in insect body. As a result, new cuticle formation is arrested and old cuticles become fractured and insect finally die (Gelbic et al, 2011;Mulder, 1973).…”

“…These compounds have been tested successfully against several insect species e.g. S. litura (Wang, 2009) and S. littoralis (Gelbic et al, 2011). In Bangladesh Buprofezin, potent chitin synthesis inhibitor (CSI) brings to table as possible alternatives of broad-spectrum insecticides in integration with other components of integrated pest management (IPM) for proper control of S. litura (Fabricius).…”

Practical approaches to adverse outcome pathway development and weight‐of‐evidence evaluation as illustrated by ecotoxicological case studies

“…Organisms exposed to these EcR agonists fail to shed their old exoskeletons during molting (i.e., incomplete ecdysis; event 990) and suffer from increased mortality (event 351) as a result of a combination of physiological abnormalities and reduced feeding. This molting defect-associated AO has been widely reported in insects such as the spruce budworm (Choristoneura fumiferana), cotton leafworm (Spodoptera littoralis), and tobacco hornworm (Manduca sexta) [14,25,28] and occasionally reported in crustaceans such as the water flea (Daphnia magna), crab (Rhithropanopeus harrisii), and barnacle (Balanus amphitrite) [29,30] for both endogenous (e.g., 20E) and exogenous (e.g., TEB) EcR agonists. Individual mortality may potentially affect the population size and ultimately cause population decline.…”

Integration betweenSteinernema feltiaeand some of environmental friendly compounds to controlSpodoptera littoralis(Lepidoptera: Noctuidae)

“…Methoxyfenozide is a potent ecdysone agonist against Lepidoptera by ingestion, and this compound is highly active, and to a lesser degree, by contact or topical application. The results indicated that Methoxyfenozide significantly reduced both of the total number of eggs laid and their hatching rate in comparison with the control similarly like tebufenozide (Gelbič et al 2011). This reduction in fecundity is most likely caused by the ecdysone agonists affecting the female reproductive system.…”