Partial aphid resistance in lettuce negatively affects parasitoids.

Area of Science:

• Agricultural Entomology
• Plant-Insect Interactions
• Chemical Ecology

Background:

• Lettuce aphid (Nasonovia ribisnigri) is a significant pest of cultivated lettuce (Lactuca sativa).
• Parasitoids, such as Aphidius ervi, are crucial biological control agents for aphids.
• Plant resistance mechanisms can influence insect performance and trophic interactions.

Purpose of the Study:

• To evaluate the impact of partial plant resistance in lettuce on the fitness of the lettuce aphid, Nasonovia ribisnigri.
• To assess the consequences of this plant resistance on the performance of the parasitoid Aphidius ervi.
• To determine if partial host plant resistance creates an ecological sink for natural enemies.

Main Methods:

• Rearing Nasonovia ribisnigri on susceptible (L. sativa) and partially resistant (Lactuca serriola) lettuce varieties.
• Parasitizing aphids with Aphidius ervi females and measuring fitness proxies.
• Quantifying aphid developmental time, fecundity, size, and weight.
• Assessing parasitoid offspring emergence, adult weight, size, and female fecundity.

Main Results:

• Aphids reared on partially resistant lettuce exhibited longer developmental times, reduced size, weight, and fecundity.
• Parasitoid offspring emergence, adult weight, size, and female fecundity were significantly reduced when developing from aphids on resistant plants.
• Partial plant resistance negatively affected both aphid herbivores and their parasitoid natural enemies.

Conclusions:

• Partial resistance in lettuce negatively impacts both aphid pests and their natural enemies.
• Cultivated lettuce with partial resistance may act as an ecological sink for aphid parasitoids.
• These findings have implications for integrated pest management and breeding for host plant resistance.