Research Highlights

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  • Ecology & evolution

Published online: 21 November 2007 | doi:10.1038/nchina.2007.246

Invasion biology: The mating arena

Wei Zeng

Introduction

© (2007) istockphoto.com/Marcus Lindström

In the animal kingdom, invasive species often take over native species by increasing the number of their offspring and eliminating the natives' offspring. Shusheng Liu at Zhejiang University in Hangzhou and co-workers¹ have discovered that whiteflies use an aggressive mating strategy to invade closely related fly colonies.

The researchers monitored whitefly populations in two parts of the world where the native populations have suffered invasion: Zhejiang, China, and Queensland, Australia. They found that, in both places, the female-to-male ratio of the invasive population is typically 10% higher than that of the native population. During invasion, the difference in female-to-male ratios between the two populations was even greater.

The researchers suspected that the invasion process had something to do with sex ratios. They tried to simulate their field results by housing invasive (13%) and native whiteflies (87%) with equal sex ratios in cages. They found that after 255 days (equivalent to about ten generations of whiteflies), the numbers of invasive type had almost completely taken over the native type. Moreover, they observed a similar shift of sex ratios among the invasive and native populations.

The researchers then conducted a series of experiments to look at the mating behaviour of the whiteflies more closely. They found that both males and females of the invasive type mate more aggressively than the native type. When there are excess males (invasive or native type), invasive males respond by courting and mating more often, as well as frequently interfering with the native males' courtship.

Whiteflies do not interbreed and they produce males from unfertilized eggs and females from fertilized eggs. Therefore the aggressive mating behaviour of the invaders will increase the number of females and ensure a higher population growth rate.

The authors of this work are from:
Institute of Insect Sciences, Zhejiang University, Hangzhou, China; CSIRO Entomology, Queensland, Australia; Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.

Reference

1. Liu, S. S. et al. Asymmetric mating interactions drive widespread invasion and displacement in a whitefly. Science doi: 10.1126/science.1149887 (2007). | Article |