# Behavioral Responses of Chrysoperla defreitasi (Neuroptera: Chrysopidae) and Myzus persicae (Hemiptera: Aphididae) to Volatile Compounds from Wild and Domesticated Ugni molinae

## TL;DR

Wild murtilla plants naturally repel pests and attract predators, but domestication has reduced these defenses, making them more vulnerable to insects like aphids.

## Contribution

The study reveals how domestication of murtilla altered its volatile chemical emissions, weakening natural defenses against pests and attracting fewer beneficial insects.

## Key findings

- Wild murtilla emits more protective volatile compounds like α-caryophyllene and 2-hexanone compared to domesticated plants.
- Domesticated murtilla attracts fewer lacewing larvae and more aphids due to reduced volatile emissions.
- Lacewing larvae and aphids show distinct preferences for specific compounds from wild and domesticated plants.

## Abstract

Many crops changed through domestication to improve traits such as yield and fruit quality, but this process often weakens their natural defenses against pests. Murtilla, a berry native to Chile, has undergone similar changes, producing fewer natural chemicals that help protect it from insects. Wild murtilla plants release more of these compounds, which attract helpful predators, such as lacewing larvae, and deter harmful pests, such as aphids. In contrast, domesticated murtilla emits fewer defensive chemicals, making it more vulnerable to aphid infestations. In this study, we compared the chemical profiles of wild and domesticated plants and tested how insects responded to them. We found that wild plants emitted higher amounts of key protective compounds, while domesticated plants produced less. Experiments showed that lacewing larvae were more attracted to certain chemicals found in wild plants, while aphids preferred those present in domesticated ones. These findings suggest that domestication unintentionally made murtilla more susceptible to pests by weakening its natural defenses. Understanding these changes can help improve future agricultural practices, potentially leading to breeding strategies that balance fruit quality with natural resistance to pests, reducing the need for chemical pesticides.

Domestication significantly altered the phenotypic and chemical traits of murtilla, notably reducing the emission of volatile compounds essential for plant–insect interactions. This reduction may affect the plant’s natural defense mechanisms, influencing its interactions with herbivores and predators. Therefore, this study tests whether domestication reduces volatile emissions in murtilla, increasing aphid preference and decreasing lacewing attraction. We selected wild ancestors (19-1, 22-1, and 23-2) from a longterm Ugni molinae germplasm bank. Crosses between these wild ancestors generated four first-generation domesticated ecotypes, 10-1, 16-16, 17-4, and 66-2, used in this study. These first-generation domesticated ecotypes were six years old at the time of the study and were used for comparisons in volatile profile and insect interaction analyses. The olfactometric preference index (OPI) for lacewing larvae and aphids revealed that wild ancestors attracted more predators than domesticated plants. For example, Ecotype 19-1 had an OPI of 1.64 for larvae and 1.49 for aphids, while Ecotype 10-1 showed lower attraction (OPI of 1.01 for larvae and 1.00 for aphids). Gas chromatography analysis identified differences in volatile organic compounds, with wild ancestor ecotypes emitting higher levels of compounds such as 2-hexanone, 1,8-cineole, and α-caryophyllene. Principal component analysis and hierarchical clustering confirmed these chemical distinctions. In olfactometer assays, lacewing larvae preferred α-caryophyllene and 2,4-dimethyl acetophenone, while aphids favored 2-hexanone and 3-hexanol. In Y-tube assays, lacewing adults showed strong attraction to α-pinene and 2,4-dimethyl acetophenone, with preferences increasing with concentration. These results indicate that domestication altered the volatile murtilla profile, reducing its attractiveness to natural predators while increasing its susceptibility to herbivores, supporting the plant domestication defense theory.