Biological activity of Dittrichia viscosa (L.) Greuter extracts against adult Sitophilus granarius (L.) (Coleoptera, Curculionidae) and identification of active compounds

Giuseppe Rotundo,Giacinto S Germinara,Antonia Barberio,Gianluca Paventi,Ivan Notardonato,Mario V Russo,Antonio De Cristofaro

doi:10.1038/s41598-019-42886-4

Giuseppe Rotundo, Giacinto S Germinara + Show 5 more

Open Access

https://doi.org/10.1038/s41598-019-42886-4

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Journal: Scientific Reports	Publication Date: Apr 23, 2019
Citations: 13	License type: open-access

Affiliation: University of Molise, University of Foggia

Abstract

Dittrichia viscosa (L.) Greuter, a perennial weed of the Mediterranean area, was reported to be source of active substances. Here, by means of both ingestion and contact assays, the biological activity of three different extracts (n-hexane, methanol, and distilled water) of D. viscosa aerial part has been evaluated against Sitophilus granarius (L.) adults, an important pest of stored grains. Ingestion assays showed negligible mortality and food deterrence for all the extracts, whereas only a slight reduction of some nutritional parameters (relative growth rate, relative consumption rate, food efficiency conversion) was recorded for water extract. High contact toxicity was found only for the n-hexane extract (24 h median lethal dose LD50 = 53.20 μg/adult). This extract was further subfractioned by silica gel column chromatography and then by thin layer chromatography. Further contact toxicity bioassays highlighted two active subfractions which were analyzed by GC-MS. This revealed the occurrence, in both subfractions, of two major peaks that were identified as α- and γ- costic acid isomers. Moreover, D. viscosa active subfractions, did not cause acetylcholinesterase (AChE) inhibition; therefore, in the light of progressive limitation of compounds acting by this mechanism of action, D. viscosa represents a promising eco-sustainable source of natural products for pest control.

Highlights

The indiscriminate use of synthetic insecticides for several decades has led to the accumulation of toxic residues in the environment and food as well as to the development of resistant pest populations[1]
The highest dose of the aqueous extract caused a significant reduction of relative growth rate (RGR) and relative consumption rate (RCR) indexes compared with control values, the resulting efficiency conversion of ingested food (ECI) was not found to be significantly different from control
Results of this study confirm D. viscosa as an important source of biologically active compounds[11,12] and, more importantly, suggest the possible application of this weed plant against stored-product pests. This consideration mostly relies on the high contact toxicity exerted by the n-hexane extract of D. viscosa aerial part against S. granarius adults

Summary

Introduction

The indiscriminate use of synthetic insecticides for several decades has led to the accumulation of toxic residues in the environment and food as well as to the development of resistant pest populations[1]. Botanical pesticides offer a good alternative to traditional chemicals in Integrated Pest Management (IPM)[4,5,6] Their use reduces the risk to non-target organisms, due to their rapid degradation in the environment, and provides novel and multiple modes of action that reduce the probability of developing pest resistance[1,7]. In this regard, the insecticidal activity of plants belonging to the Asteraceae family has been investigated in many previous studies[8,9,10]. Control of the granary weevil is difficult due to the endophytic development of immature stages that are well protected within grains from pesticides, the increasing legislation limits to the use of some fumigants and broad-spectrum contact insecticides, and the increasing consumer demand for safe food[30]

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