Abstract
For insects, female density is closely related to reproductive output. However, little is known about the effects of female density on male mating and female postmating performances. Here, we explored the effects of female density in cotton mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), an invasive, rapidly spreading pest in Asia damaging multiple crops and horticultural plants. Using USB digital microscopes, we investigated the frequency, duration, and intervals of mating for males that were individually supplied with 1, 5, 10, and 15 females. We also evaluated the reproduction of mated females and the sex ratio of their offspring. As the female density increased, males mated with more females while substantially shortening mating intervals. Mating occurred actively at the densities of 10 and 15 females, where males mated four times on average, and some mated 6–9 times. However, mating duration and the observed reproductive parameters of females (preoviposition period, overall period from formation of ovisacs to female death, fecundity, and offspring sex ratio) did not differ significantly with female density. A weak trade-off existed between males’ mating frequency and longevity, but there was no relationship between females’ fecundity and longevity. In conclusion, despite their short lifespan, P. solenopsis males have a high mating capacity, and their mating frequency and intervals can be significantly affected by female density. In contrast, female density has little influence on females’ postmating performance. Our findings indicate the significance of the reproductive biology and life history strategies for rapid establishment and population development of mealybugs in newly invaded regions.
Highlights
Female density is closely related to reproductive output
Insects and Host Plants P. solenopsis used in this study were derived from a colony that was established from individuals collected from the ornamental plant, Rose of Sharon, Hibiscus syriacus L. (Malvales: Malvaceae) in Jinhua, central Zhejiang, China, in June 2016
This colony was reared on tomato plants in a climatically controlled chamber maintained at 27 ± 1°C and 75% relative humidity (RH) with a photoperiod of 14:10 (L:D) h
Summary
Female density is closely related to reproductive output. little is known about the effects of female density on male mating and female postmating performances. The solenopsis mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), is native to North America, and is an invasive alien pest in Asia and beyond (Wang et al 2010) It can rapidly establish and develop population in newly invaded regions, and is continually extending its geographic range because of its adaptive life features, including its broad host range, high fecundity, protective benefits from mutualistic ants, and its ability to adapt to diverse abiotic environmental conditions (reviewed by Tong et al 2018). Both adults and crawlers damage plants by sucking cell sap from phloem tissue of leaves, stems, twigs, flower buds, and young bolls, causing premature leaf drop, dieback, and even the death of whole plant. The mating and reproductive features of P. solenopsis have attracted much research interest, including its mating frequency (Wei et al 2010), mating duration (Wei et al 2010, Zhang et al 2015), mating preferences (Xu et al 2016), fecundity (Wang et al 2014), and associations between mating and females’ ovarian development and oviposition (Huang et al 2013, Zhang et al 2015, Arif et al 2016). Wei et al (2010) reported that males of cotton mealybug mated only once during their lifetime, but an average of 4.5 matings was reported by Wang et al
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