Neonicotinoid pesticide applications affect pollinator abundance and visitation, leading to implications for sunflower production (Helianthus annuus L.)

Abstract

AbstractPesticides are considered a risk to pollinators; however, little is known about the possible effects of their injudicious use on pollinators, including the ecosystem services provided to crops and wildflowers. Recently, great attention has been paid to the effects of neonicotinoids pesticides on pollinators and their potential role in harming the health of bees all over the world. Sunflowers, being self-incompatible plants, rely on insects, primarily bees, for effective cross-pollination and successful seed-set. Ensuring the presence of sufficient pollinators in the field is crucial for facilitating pollen movement between flowers and promoting optimal seed development. However, the reliance on insect-mediated cross-pollination also makes sunflowers susceptible to pest attacks, which can negatively impact seed production. To mitigate these potential threats and achieve increased seed yields, careful consideration is given to the judicious use of pesticides. Striking the right balance between providing adequate pollinators and implementing appropriate pest management strategies is vital for maximizing sunflower crop productivity. To reveal such potential impacts of neonicotinoid insecticides, we undergo the current study that aimed to estimate flower visitation and pollination in a sunflower crop by applying three neonicotinoid insecticides i.e. imidacloprid, clothianidin, and thiamethoxam, including the control group for two years i.e. 2020, and 2021. In all experimental plots, we quantified floral visitors for fourteen days at three different times (8 am, 12 pm, and 5 pm). Floral visitors were divided into three groups, Apis bees, Non-Apis bees, and butterflies. After the maturation period, the achenes from each capitulum were separated and brought for weight. We discovered that this study confirmed the adverse effect of neonicotinoids pesticides on sunflower production.Our research revealed that the use of imidacloprid, clothianidin, and thiamethoxam had a negative impact on the visitation of Apis bees, with reductions of 19%, 18.5%, and 23% respectively, as compared to the control group during the year 2020. Furthermore, these pesticides also caused a decrease in the visitation of Non-Apis bees by 15%, 15%, and 17% respectively. The visitation of butterflies was also affected, with reductions of 17.4%, 14.6%, and 15.8% for imidacloprid, clothianidin, and thiamethoxam respectively. Based on our research conducted in the year 2021, the use of imidacloprid, clothianidin, and thiamethoxam caused a reduction of 22.5%, 24%, and 25.5% respectively in the visitation of Apis bees, as compared to the control group. Similarly, non-Apis bees experienced a decrease in visitation by 19.5%, 23.5%, and 25% respectively for imidacloprid, clothianidin, and thiamethoxam, compared to the control group. The visitation of butterflies was also affected, with reductions of 18.2%, 22.2%, and 26% respectively for imidacloprid, clothianidin, and thiamethoxam, compared to the control group. Our findings suggest that the use of these pesticides affected the diversity of floral visitors and contributed to a decline in the number of fruit during the year 2020 and 2021.Moreover, the abundance of floral visitors, the mass of fruits, and the quantity of oil in the seeds were significantly lower after treatment with neonicotinoid pesticides, thus evidencing its negative effect on sunflower productivity. [Figure: see text]

Keywords

• Sunflower
• Abundance
• Pollinators
• Neonicotinoids
• Pesticide toxicity
• Productivity