What question did this study set out to answer?

To determine how varying LED daylength extensions influence the daily activity patterns of Aphidius matricariae.

March 10, 2026Open Access

The Effects of LED Daylength Extensions on the Daily Activity Patterns of a Greenhouse Biological Control Agent, Aphidius matricariae

JFJ. W. FraserAgriculture and Agri-Food Canada PAPaul K. AbramAgriculture and Agri-Food Canada MDMartine Dorais

Key Points

To determine how varying LED daylength extensions influence the daily activity patterns of Aphidius matricariae.
Examined locomotor activity of Aphidius matricariae under different photoperiods: 14, 16, 18, and 20 hours, and 12-hour days extended by 6 hours.
Utilized various spectral qualities of LED lighting to assess effects on activity patterns.
Conducted experiments in growth chambers over multiple days.
Parasitoids adjusted their daily activity distribution without changing total daily activity.
Activity duration and peak timing shifted due to different photoperiods and light spectra but overall activity remained consistent.
Findings suggest behavioral traits of parasitoids show resilience to LED light changes.

Abstract

ABSTRACT Supplemental lighting, such as with LED lamps, allows greenhouse producers to maintain yields when natural light levels are low. Since both insect pests and their natural enemies are sensitive to light, both the duration and spectrum of LED daylength extensions could affect biological pest control in greenhouses. For example, they could extend periods of foraging activity for biological control agents. Insect responses to light can be species‐specific, so it would be useful to have a high‐throughput method to study the effects of novel light regimes on many different greenhouse biological control agents. It is unknown to what extent parasitoids change their daily activity patterns under longer days due to artificial illumination on multi‐day timescales. In growth chambers, we examined the locomotor activity of the parasitoid biocontrol agent Aphidius matricariae Haliday (Hymenoptera: Braconidae) over multiple days under different illumination regimes. We compared the effects of 14, 16, 18, and 20 h photoperiods, and 12 h days extended by 6 h with three different spectral qualities. The parasitoids adjusted how their activity was distributed throughout the lit period of the day (i.e., total activity duration and peak timing) without changing the total amount of daily activity, regardless of the photoperiod or the light spectrum used for daylength extension. Our results suggest that at least some behavioral traits of parasitoids can be resilient to changes in their light environment, and may help to mechanistically interpret subsequent experiments showing that their biological control effects are also resilient to different LED lighting regimes. This experimental approach may be useful in screening other biological control agents for strong responses to LED spectra or artificially‐extended photoperiods, which can then be confirmed through more in‐depth research in more realistic settings.

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