The First Evidence of the Insecticidal Potential of Plant Powders from Invasive Alien Plants against Rice Weevil under Laboratory Conditions

Abstract

In a laboratory experiment, we studied the insecticidal effects of invasive alien plants on the rice weevil. The research was carried out in two parts. In the first part, we studied the insecticidal properties of seven different plant species, namely, Bohemian knotweed (Fallopia × bohemica), Japanese knotweed (Fallopia japonica), false indigo-bush (Amorpha fruticosa), tree of heaven (Ailanthus altissima), staghorn sumac (Rhus typhina), Canada goldenrod (Solidago canadensis), and giant goldenrod (Solidago gigantea). Mixtures of powders and wheat were prepared in two different concentrations, namely, 2.5 w% and 1.25 w%. The experiment was performed at temperatures 20 °C and 25 °C and at two humidity levels, 55% R.h. and 75% R.h. Very low mortality (below 8%) was found when using combinations with the higher relative humidity. No significant differences were observed between the effects of these concentrations. In the second part of the experiment, Norway spruce wood ash and diatomaceous earth (product SilicoSec®) were added to the powder obtained by milling leaves of four different invasive plant species (Canada goldenrod, staghorn sumac, tree of heaven, false indigo). In the independent application, wheat was added to the powder at a concentration 2.5 w%. In the treatments that involved mixtures of powder and wood ash/diatomaceous earth, we applied 1.25 w% plant powder and 1.25 w% wood ash or 1.25 w% plant powder and 450 ppm of a SilicoSec® preparation. The positive control was carried out as two separate treatments with 2.5 w% wood ash of Norway spruce and 900 ppm of the SilicoSec® product, while untreated wheat represented the negative control. The experiment was performed at two temperatures (20 °C and 25 °C) and two R.h. values (55 and 75% R.h.). The mortality of beetles was recorded on the 7th, 14th, and 21st day after the start of the experiment. Higher mortality rates of rice weevil adults were found at the higher relative humidity, and an important factor of mortality was also the day of exposure, as a higher mortality was found when the exposure of individuals to the tested substances was for a longer time period. After 21 days at 25 °C and 55% R.h., the combinations in which the lower concentration of Norway spruce wood ash was added to the powder of invasive alien plants achieved more than 90% mortality of beetles. By adding the plant powder of invasive alien plants to wood ash, we achieved a greater insecticidal efficacy of invasive plants and lower concentrations of wood ash. Nevertheless, the results of our research do not indicate any great usefulness of the plant powder of invasive plants in suppressing the rice weevil. Additional studies should primarily focus on the insecticidal efficacy of powder from the genus Solidago, which in our study, displayed the greatest insecticidal potential among the tested invasive plants.

Effect of Tasmanian blue gum (Eucalyptus globulus Labill.) leaf extract on cowpea weevil (Callosobruchus maculatus [Fabricius, 1775], Coleoptera: Chrysomelidae)

“…The use of natural toxicants from plants as insecticides had been existent since the ancient times (Bohinc et al, 2013) and is investigated in recent times (Bohinc et al, 2020) The natural insecticides which require low cost to prepare, are readily available, environmentally and ecologically friendly are best suited for use in the storage of produce. Botanical control is said to be the best pest control of stored grain pests because it is biodegradable, environmentally friendly and does not leave toxic residues.…”

Antifeeding and Insecticidal Activity of Ailanthus altissima and Morus alba Extracts Against Gipsy Moth (Lymantria dispar (L.), Lepidoptera, Lymantridae) Larvae Under Laboratory Conditions

“…Plants are a rich source of compounds that exhibit high biological activity against harmful insects, thus botanical preparations are good potential substitutes for synthetic insecticides in agricultural and forest pest control (Bohinc et al, 2020;Šućur et al, 2015;Hikal, Baeshen & Said-Al Ahl, 2017;Gvozdenac, Šućur, Manojlović, Prvulović & Malenčić, 2018). In recent years, antifeeding effects of various plants and plant extracts have been studied for gypsy moth larvae and several findings confirm the antifeedant or repellent activity of Pinus taeda L., Juniperus virginiana L., Acer rubrum L. (Keena & Richards, 2020), Ocimum basilicum L. (Kostić et al, 2008;Popović et al, 2013), Morus alba L. and Aesculus hippocastanum L. (Gvozdenac, Inđić, Vuković, Grahovac & Tanasković, 2012).…”

New Insights Into Biopesticides: Solid and Liquid Formulations of Essential Oils and Derivatives

“…The recent development of natural plant protection products has been successful, being approved for pest control and integrated into agricultural practice with the support of organizations authorized to market these products (Bohinc et al, 2020). The most commonly used commercial EOs include eugenol (e.g., clove and laurel oils), pine, anise, eucalyptus, and thyme oils (Lubbe and Verpoorte, 2011).…”