Direct and Ambient Light Pollution Alters Recruitment for a Diurnal Plant-Pollinator System

Area of Science:

• Ecology
• Pollination Biology
• Environmental Science

Background:

• Artificial light at night (ALAN) is an emerging environmental factor impacting species interactions.
• Nocturnal pollinator responses to ALAN are known, but effects on diurnal pollinators and underlying mechanisms are unclear.
• The obligate mutualism between yucca moths and yucca plants provides a model to study ALAN's influence on plant-pollinator dynamics.

Purpose of the Study:

• To investigate how direct light and skyglow from ALAN affect the yucca moth-yucca plant mutualism.
• To determine if adult yucca moths exhibit positive phototaxis (attraction to light).
• To assess the impact of ALAN on yucca plant reproductive success (fruit set) and moth larval recruitment.

Main Methods:

• Field experiments using light towers during peak yucca flowering to simulate ALAN conditions.
• Comparison of moth abundance in light-treated versus dark-controlled traps to assess phototaxis.
• Measurement of skyglow and direct light intensity to correlate with fruit set and larval recruitment.

Main Results:

• Adult moth abundance significantly increased in the presence of artificial light, suggesting altered activity patterns.
• Both fruit set and larval recruitment increased with skyglow exposure.
• Fruit set showed a weaker increase with direct light, while larval recruitment was unaffected by direct light, possibly due to physiological impacts on moths.

Conclusions:

• ALAN can positively influence the fitness of both yucca plants and moths in their mutualistic relationship.
• The benefits of ALAN depend on whether the light exposure is direct or indirect (skyglow).
• Further research is needed to understand the broader implications of ALAN on plant-pollinator relationships and potential susceptibility mechanisms.