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Application of neem seed kernel extracts result in mouthpart deformities and subsequent mortality in Nezara viridula (L.) (Hem: Pentatomidae)
Author(s) -
Singha A.,
Thareja V.,
Singh A. K.
Publication year - 2007
Publication title -
journal of applied entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.795
H-Index - 60
eISSN - 1439-0418
pISSN - 0931-2048
DOI - 10.1111/j.1439-0418.2006.01134.x
Subject(s) - nezara viridula , biology , pentatomidae , instar , nymph , toxicology , arthropod mouthparts , botany , horticulture , heteroptera , larva , zoology
The effect of topical application of neem seed kernel aqueous suspension (NSKAS) and neem seed kernel hexane extract (NSKHE) on 2‐day‐old fourth instar nymphs of Nezara viridula (L.) was studied under laboratory conditions. The applications resulted in loosening of the proboscis, along with separation and deformation of mouthparts, predominantly in the stylets in fifth instar nymphs, adults and in inter‐stadial moults. This rendered the insects incapable of feeding and led them to death. Application of NSKAS at 2.5% concentration led to 100% mortality, of which 40% was due to mouthpart deformities. Application of NSKHE at 2.5% concentration led to only 70% mortality, of which 3.33% was due to mouthpart deformities. At 5% concentration, mortality was again 100% for NSKAS and reached close to 100% for the NSKHE application. Dose‐dependent mortality was observed for both the applications. However, dose‐dependent mouthpart deformities were observed only for NSKAS, the highest being 60% at the 5% concentration. Moreover, for both the applications, more than 50% of the total mortality was observed up to the fifth instar at almost all the concentrations. The LC 50 values for NSKAS and NSKHE applications, for mortality up to the fifth instar were 0.36% and 5.22%, and for mortality to the adult stage (10 days old) they were 0.23% and 1.32% respectively. The percentage of bugs showing mouthpart deformities and toxicity was higher for NSKAS than NSKHE, and indicated that NSKAS was more potent than NSKHE.