Impact of Larinus latus Infestation on the Growth and Reproductive Performance of Silybum marianum under Field Conditions in Egypt
Sharshar A. A. H
The Survey, Ecology and Physiological Weeds Department, Weed Research Central Laboratory (WRCL), Agricultural Research Center (ARC), Giza, Egypt.
Abd-Elsalam A. Farag *
Department of Cotton Pesticides Evolution, Plant Protection Research Institute, Agriculture Research Centre, 12619 Giza, Egypt.
Mousa, R. A.
Weed Control in Hort. Crops- Department, (WRCL), ARC, Giza, Egypt.
H. M. Amine
Plant Protection Dep. Faculty of Agriculture Tanta University, Egypt.
Azza E. Khaffagy
Weed Control in Field Crops Department, (WRCL), ARC, Giza, Egypt.
*Author to whom correspondence should be addressed.
Abstract
Larinus latus is one of the most important phytophagous insects associated with Silybum marianum weed (milk thistle). A comprehensive field survey was conducted over two consecutive winter growing seasons (2023/2024 and 2024/2025) starting in January for both seasons in El-Beheira and Kafr El-Sheikh Governorates, Egypt. The study aimed to assess the biological impact of L. latus infestation on key reproductive traits of S. marianum, including the number and fresh weight of insect-infested inflorescences and their seeds, across multiple field locations (18 sites in each governorate). The main findings showed that insect infestation of S. marianum inflorescences caused a marked reduction in fresh weight and resulted in the production of fewer and lighter seeds compared with uninfected inflorescences in both seasons. Moreover, insect infestation significantly inhibited the reproductive capacity of S. marianum, suggesting a regulatory role in limiting its growth. This study underscores the ecological importance of weed–insect interactions and supports the potential for incorporating insect-induced effects into integrated and sustainable management strategies for S. marianum weed.
Keywords: Larinus latus, Silybum marianum, biological weed control, insect infestation