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Effect of Bacillus thuringiensis B. in mixed with Neemarin and Matrine against forest pest, Lymantria dispar L. | ||
| تحقیقات حمایت و حفاظت جنگلها و مراتع ایران | ||
| Article 8, Volume 22, Issue 2 - Serial Number 44, March 2025, Pages 268-284 PDF (596.46 K) | ||
| Document Type: Research Paper | ||
| DOI: 10.22092/ijfrpr.2024.367089.1641 | ||
| Authors | ||
| Mahdieh Mousavi1; Shahram Aramideh* 2; Samaneh Akbari1 | ||
| 1PhD in Entomology, Department of Plant Protection, Faculty of Agriculture, Urmia University, Urmia, Iran | ||
| 2Corresponding author, Associate Professor., Department of Plant Protection, Faculty of Agriculture, Urmia University, Urmia, Iran | ||
| Abstract | ||
| Background and objectives: The gypsy moth, Lymantria dispar L., is one of the most significant pests of forest and orchard trees, feeding on a wide range of tree and shrub species. Larval feeding on tree leaves is a common occurrence that severely impacts tree growth and productivity. Even if infested trees do not die, they experience significant reductions in growth and yield in subsequent years, leading to irreversible damage. Chemical control poses serious risks, including the destruction of natural enemies, pest resistance, secondary pest outbreaks, and environmental pollution. Therefore, this study aimed to evaluate the efficacy of botanical pesticides Neemarin and Matrine, in combination with the microbial pesticide Bacillus thuringiensis subsp. kurstaki (Btk), for controlling L. dispar larvae. Methodology: Egg masses of L. dispar were collected from infested black poplar (Populus nigra L.) trees on the Nazloo campus of Urmia University in 2023 and reared on fresh poplar leaves in a growth chamber. The leaves were replaced daily with fresh ones. The microbial pesticide used was the commercial formulation Belthirul, based on Btk (Problet, Madrid, Spain). Neemarin (Neemarin EC15%) is an Azadirachta indica Juss A. extract containing azadirachtin, manufactured in India and procured from the Iranian Research Institute of Plant Protection. Matrine (brand name: Rui Agro) is a contact and oral insecticide derived from Sophora flavescens Ait., produced in China under the supervision of Ecocert France. Bioassay experiments were conducted to assess the effects of Neemarin, Matrine, and Btk individually and in combination on second and third instar larvae. Additionally, the impact of sublethal concentrations (LC25) of these compounds on pest metamorphosis (larval-to-pupal and pupal-to-adult transformation) was evaluated under laboratory conditions using a germinator (27±2 °C, 65±5% relative humidity). The effectiveness of recommended concentrations was also tested on third instar larvae under field conditions. Results: Probit analysis of different concentrations of Neemarin (150.00, 267.50, 385.00, 502.50, 620.00 ppm), Matrine (22.50, 38.25, 54.00, 69.75, 85.50 ppm), and Btk (300.00, 712.50, 1125.00, 1537.50, 1950.00 ppm) after 24 and 48 hours showed that Matrine had higher toxicity (lower LC50) than Neemarin and Btk. The combined treatments demonstrated significant differences (P<0.05), with the Neemarin+Matrine+Btk mixture causing the highest larval mortality after 72 hours in both instars. Under field conditions, the highest third instar larval mortality was observed in the Neemarin+Matrine treatment, followed by Matrine+Btk. Evaluating sublethal concentrations of Neemarin (136.94 ppm), Matrine (15.92 ppm), and Btk (302.75 ppm) on larval metamorphosis revealed that Neemarin had the highest inhibitory effect on larval transformation to pupae and pupal development into adults. Conclusion: Given the limitations and adverse effects of chemical pesticides, the use of biological and botanical alternatives for pest control is essential. The results of this study demonstrated that these biological compounds, both individually and in combination, effectively control L. dispar larvae under laboratory and field conditions. Additionally, sublethal concentrations significantly disrupted the pest’s life cycle. Therefore, these bio-insecticides, particularly in combination, can be recommended as effective alternatives for managing L. dispar larvae and similar pests in forests and orchards. | ||
| Keywords | ||
| Forest pest; plant pesticides; microbial pesticides; biological control | ||
| References | ||
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