Factors Affecting the Ratio of Female to Male of Pinewood Nematodes Bursaphelenchus xylophilus (Steiner &amp; Buhrer) Nickle

Pengfei Wei,Wei Zhang,Yongxia Li,Xingyao Zhang,Mengge Gao,Zhenkai Liu

doi:10.3390/f12060763

Factors Affecting the Ratio of Female to Male of Pinewood Nematodes Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle

Pengfei Wei, Wei Zhang + Show 4 more

Open Access

https://doi.org/10.3390/f12060763

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Abstract

The pinewood nematode Bursaphelenchus xylophilus (B. xylophilus) is responsible for a devastating disease of pine forests. Its pathogenicity is closely related to the numbers of individual B. xylophilus. The ratio of female to male (sex ratio) is key to understanding population change in this species. The sex ratio of B. xylophilus varies widely, but it is unclear how it is affected by environmental changes. The sex ratios of nematodes, isolated from different samples in the wild, varied between 0.93 and 2.20. Under laboratory conditions, maternal age and the population did not affect the sex ratio of progeny. A change from good to poor nutritional status was associated with a reduction of the sex ratio of progeny from 1.85 to 1.41, which was speculated to result from a change in the primary sex ratio. Thus, B. xylophilus effectively maintains the sex ratio with maternal age and population changes but adjusts the sex ratio of progeny on the basis of the changes in nutrition.

Highlights

In the samples collected from different regions, the sex ratio of pinewood nematode varied between 0.93 and 2.20 (Table 1)
The sex ratios of B. xylophilus in the propagative phase collected from the pine trees deviated significantly from 1.0 (N = 6, df = 5, p = 0.001, one-sample t-test), and were female biased
As it is difficult to distinguish the sex of the L2 stages, it was not included in the calculations; the sex ratios of L3, L4, and adults were not significantly different (1.90 ± 0.06, 1.90 ± 0.05, and 1.94 ± 0.03, respectively)

Summary

Introduction

In addition to elucidating relationships among the sexual selection, population dynamics, and evolutionary trajectories [1,2,3,4], it is the focal point of adaptive allocation strategies in which individuals match current and expected fitness payoffs through the adjustments to their relative investment in males and females [5,6,7]. In both natural and experimental infections of acanthocephalan and nematode parasites, the sex ratio is often biased toward females among the adult population [8].

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