Laboratory evaluation of the effects of Manilkara subsericea (Mart.) Dubard extracts and triterpenes on the development of Dysdercus peruvianus and Oncopeltus fasciatus

Abstract

The results indicate that extracts and triterpenes from Manilkara subsericea act as potent growth inhibitors of phytophagous hemipteran nymphs. It is also concluded that the mixture of several different molecules in the extracts used produces synergic effects that do not occur after using the triterpenes (PFT) alone. These secondary metabolites in the M. subsericea extracts can potentially be used in integrated control programmes against crop pests.

Development of an insecticidal nanoemulsion with Manilkara subsericea (Sapotaceae) extract

“…Perhaps, differences in the speed of absorption between HFNE and blank nanoemulsion by insect metabolic systems may explain this not expectable result. Physiological mechanisms of metabolization of these compounds by invertebrates remains unknown [9] and is now under investigation by our research group.…”

“…Acetylthiocholine iodide (ATCI), 5,5-dithiobis-2-nitrobenzoic acid (DTNB), physostigmine (eserine) and acetylcholinesterase from electric eel (type VI-S, C3389-2UK, lyophilized powder) were purchased from Sigma (Sigma-Aldrich Corporation, St Louis, MO). Hexane-soluble fraction from fruits of M. subsericea was previously obtained [9] and stored at 4°C for further utilization.…”

“…Dysdercus peruvianus were obtained from the colony maintained in the Laboratory of Insect Biology of the Universidade Federal Fluminense (GBG-UFF), being kept at 24-25°C, relative humidity of 70-75% and a 16:8 h light:dark cycle [9]. …”

“…Several non-polar pentacyclic triterpenes have been described as major constituents of M. subsericea , mainly alpha- and beta-amyrin esters [7,8]. Hexane-soluble fraction from ethanolic crude extract from fruits of M. subsericea and its major substances (alpha- and beta-amyrin acetate) was able to induce mortality, delayed development and inhibition of moulting in Dysdercus peruvianus [9], a hemiptera species which causes serious loss of cotton crops [10]. This apolar fraction and its triterpenes have poor water solubility and are soluble in toxic organic solvents, such as chloroform and dichloromethane, being this intrinsic characteristic a technological challenge if development if a viable product is desired.…”

Bioactivity of the latex from Parahancornia amapa (Apocynaceae) on the development of Rhodnius nasutus (Hemiptera, Reduviidae, Triatominae) under laboratory conditions

“…There is no report of any morphological alterations of R. nasutus in the literature. However, some authors have Bioactivity of the latex from P. amapa on the development of R. nasutus under laboratory conditions reported that natural extracts can cause morphological alterations in insect species (Fernandes et al 2012;Cabral et al 2000). These morphological alterations found using the scanning electron microscopy can hinder the locomotion of the insect and decrease the dispersion activity of the triatomine.…”