Species of Apocynaceae are pollinated by a diverse assemblage of animals. Here we report the first record of specialized cockroach pollination in the family, involving an endangered climbing vine species, Vincetoxicum hainanense in China. Experiments were designed to provide direct proof of cockroach pollination and compare the effectiveness of other flower visitors. METHODS: We investigated the reproductive biology, pollination ecology, pollinaria removal, pollinia insertion, and fruit set following single visits by the most common insects. In addition, we reviewed reports of cockroaches as pollinators of other plants and analyzed the known pollination systems in Vincetoxicum in a phylogenetic context. RESULTS: The small, pale green flowers of V. hainanense opened during the night. The flowers were not autogamous, but were self-compatible. Flower visitors included beetles, flies, ants and bush crickets, but the most effective pollinator was the cockroach Blattella bisignata, the only visitor that carried pollen between plants. Less frequent and effective pollinators are ants and Carabidae. Plants in this genus are predominantly pollinated by flies, moths and wasps. CONCLUSIONS: Globally, only 11 plant species are known to be cockroach-pollinated. Because their range of floral features encompass similarities and differences, defining a "cockroach pollination syndrome" is difficult. One commonality is that flowers are often visited by insects other than cockroaches, such as beetles, that vary in their significance as pollinators. Cockroach pollination is undoubtedly more widespread than previously thought and requires further attention.

Vincetoxicum hainanense is an endangered liana species endemic to China. Habitat destruction coupled with difficulties in natural pollination has reduced its population size over time. As present studies have focussed more on breeding programmes instead of molecular aspects, here we reported on the complete chloroplast (cp) genome sequence of V. hainanense. The cp genome is 161,280 bp in size and includes two inverted repeat (IR) regions of 24,884 bp each, which is separated by a large-single copy (LSC) region of 92,084 bp and a small-single copy (SSC) region of 19,428 bp. A total of 131 genes were predicted, including 37 tRNA, 8 rRNA, and 86 protein-coding genes. Phylogenetic analysis showed that V. hainanense is clustered with other Apocynaceae species and sister to Biondia chinensis.

A high efficiency output structure which is designed for W band gyrotron traveling wave tube (Gyro-TWT) is presented in this paper. With the aid of numerical calculation in Matlab, the contour of the cascaded Chebyshev tapered waveguide is got. Based on the optimized results from HFS S , the cascaded Chebyshev tapered waveguide satisfies the requirement which S 21 is more than -0.045dB and S 11 is less than -20dB in the whole working band and its size is practicable.