A Simple and Efficient Method for Correction of Basin-Scale Evapotranspiration on the Tibetan Plateau

Evapotranspiration (ET) is one of the important components of the global hydrologic cycle, energy exchange, and carbon cycle. However, basin scale actual ET (hereafter ETa) is difficult to estimate accurately. We present an evaluation of four actual ET products (hereafter ETp) in seven sub-basins in the Tibetan Plateau. The actual ET calculated by the water balance method (hereafter ETref) was used as the reference for correction of the different ETp. The ETref and ETp show obvious seasonal cycles, but the ETp overestimated or underestimated the ET of the sub-basins in the Tibetan Plateau. A simple and effective method was proposed to correct the basin-scale ETp. The method was referred to as ratio bias correction, and it can effectively remove nearly all biases of the ETp. The proposed method is simpler and more effective in correcting the four ETp compared with the gamma distribution bias correction method. The reliability of the ETp is significantly increased after the ratio bias correction. The ratio bias correction method was used to correct the ETp in the seven sub-basins in the Tibetan Plateau, and regional ET was significantly improved. The results may help improve estimation of the ET of the Tibetan Plateau and thereby contribute to a better understanding of the hydrologic cycle of the plateau.

Spatial and temporal sex ratio bias and Wolbachia-infection in New Zealand Crambidae (Lepidoptera: Pyraloidea)

The New Zealand fauna of snout moths (Pyraloidea) predominantly consists of endemic species. During 2017 and 2018, 56 species of Pyraloidea in 1,749 individuals were collected at 14 localities. All species were screened for Wolbachia-infection, with specimens of eight species (14%) being positive, of which six species belong to Scopariinae. This is the first record of Wolbachia-infection amongst New Zealand Lepidoptera. The most common pyraloid species, Eudonia submarginalis and Orocrambus flexuosellus, were analysed for a larger set of individuals looking for sex ratio and Wolbachia-infection. There is a sex ratio bias towards females in both species, but it varies in space and time. Wolbachia is found in all populations of E. submarginalis with 10–80% of the tested individuals being positive, depending on locality. No Wolbachia-infection has been found in O. flexuosellus. Thus, sex ratio bias might be linked to Wolbachia-infection in E. submarginalis, but not in O. flexuosellus.

Sexual dimorphism and sex ratio bias in the dioecious willow Salix purpurea L

PremiseSexual dimorphism in dioecious plant species is often not obvious or is absent. Dioecious species populations also often exhibit deviations from expected sex ratios. Previous studies on members of the Salicaceae family have shown strong, partial, and no sexual dimorphism. Some studies have shown sex-biased ratios in several Salix spp., however, S. purpurea has never been examined for evidence of sexual dimorphism or for the presence of sex-ratio bias, and therefore a comprehensive phenotypic study is needed to fill this knowledge gap.MethodsThis study examined a suite of morphological, phenological, physiological and wood composition traits from multi-environment and multi-year replicated field trials in a diversity panel of unrelated S. purpurea accessions and in full-sib F1 and F2 families produced through controlled cross pollinations to test for sexual dimorphism and sex ratio bias.Key ResultsSignificant evidence of sexual dimorphism was found in vegetative traits with greater means for many traits in male genotypes compared to females across three populations of S. purpurea, measured across multiple years that were highly predictive of biomass yield. Male plants exhibited greater nitrogen accumulation under fertilizer amendment as measured by SPAD in the diversity panel, and males showed greater susceptibility to fungal infection by Melampsora spp in the F2 family. There were also consistent female-biased sex ratios in both the F1 and F2 families.ConclusionsThese results provide the first evidence of sexual dimorphism in S. purpurea and also confirm the prevalence of female-biased sex ratios previously found in other Salix species.

Female bias in an immigratory population of Cnaphalocrocis medinalis moths based on field surveys and laboratory tests

Sex ratio bias is common in migratory animals and can affect population structure and reproductive strategies, thereby altering population development. However, little is known about the underlying mechanisms that lead to sex ratio bias in migratory insect populations. In this study, we used Cnaphalocrocis medinalis, a typical migratory pest of rice, to explore this phenomenon. A total of 1,170 moths were collected from searchlight traps during immigration periods in 2015–2018. Females were much more abundant than males each year (total females: total males = 722:448). Sex-based differences in emergence time, take-off behaviour, flight capability and energy reserves were evaluated in a laboratory population. Females emerged 0.78 days earlier than males. In addition, the emigratory propensity and flight capability of female moths were greater than those of male moths, and female moths had more energy reserves than did male moths. These results indicate that female moths migrate earlier and can fly farther than male moths, resulting more female moths in the studied immigratory population.