BackgroundTo understand the processes of invasions by alien insects is a pre-requisite for improving management. The whitefly Bemisia tabaci is a cryptic species complex that contains some of the most invasive pests worldwide. However, extensive field data to show the geographic distribution of the members of this species complex as well as the invasion by some of its members are scarce.Methodology/Principal FindingsWe used field surveys and published data to assess the current diversity and distribution of B. tabaci cryptic species in China and relate the indigenous members to other Asian and Australian members of the complex. The survey covered the 16 provinces where indigenous B. tabaci occur and extends this with published data for the whole of China. We used molecular markers to identify cryptic species. The evolutionary relationships between the different Asian B. tabaci were reconstructed using Bayesian methods. We show that whereas in the past the exotic invader Middle East-Asia Minor 1 was predominant across China, another newer invader Mediterranean is now the dominant species in the Yangtze River Valley and eastern coastal areas, and Middle East-Asia Minor 1 is now predominant only in the south and south eastern coastal areas. Based on mtCO1 we identified four new cryptic species, and in total we have recorded 13 indigenous and two invasive species from China. Diversity was highest in the southern and southeastern provinces and declined to north and west. Only the two invasive species were found in the northern part of the country where they occur primarily in protected cropping. By 2009, indigenous species were mainly found in remote mountainous areas and were mostly absent from extensive agricultural areas.Conclusions/SignificanceInvasions by some members of the whitefly B. tabaci species complex can be rapid and widespread, and indigenous species closely related to the invaders are replaced.

Abstract-The use of peer-to-peer (P2P) applications is growing dramatically, particularly for sharing large video/audio files and software. In this paper, we analyze P2P traffic by measuring flowlevel information collected at multiple border routers across a large ISP network, and report our investigation of three popular P2P systems-FastTrack, Gnutella, and Direct-Connect. We characterize the P2P trafffic observed at a single ISP and its impact on the underlying network. We observe very skewed distribution in the traffic across the network at different levels of spatial aggregation (IP, prefix, AS). All three P2P systems exhibit significant dynamics at short time scale and particularly at the IP address level. Still, the fraction of P2P traffic contributed by each prefix is more stable than the corresponding distribution of either Web traffic or overall traffic. The high volume and good stability properties of P2P traffic suggests that the P2P workload is a good candidate for being managed via application-specific layer-3 traffic engineering in an ISP's network.

Abstract-The use of peer-to-peer (P2P) applications is growing dramatically, particularly for sharing large video/audio files and software. In this paper, we analyze P2P traffic by measuring flowlevel information collected at multiple border routers across a large ISP network, and report our investigation of three popular P2P systems-FastTrack, Gnutella, and Direct-Connect. We characterize the P2P trafffic observed at a single ISP and its impact on the underlying network. We observe very skewed distribution in the traffic across the network at different levels of spatial aggregation (IP, prefix, AS). All three P2P systems exhibit significant dynamics at short time scale and particularly at the IP address level. Still, the fraction of P2P traffic contributed by each prefix is more stable than the corresponding distribution of either Web traffic or overall traffic. The high volume and good stability properties of P2P traffic suggests that the P2P workload is a good candidate for being managed via application-specific layer-3 traffic engineering in an ISP's network.

The invasive Middle East‐Asia Minor 1 (MEAM1) cryptic species (formerly referred to as the B ‘biotype’) of the whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) complex has become a major crop pest worldwide due to its global invasion as well as epidemics of begomoviruses it transmits. Previous studies demonstrated that MEAM1 performed better on tobacco [Nicotiana tabacum L. (Solanaceae)] plants infected by Tomato yellow leaf curl China virus (TYLCCNV) than on uninfected plants. However, mechanisms underlying the interactions are not completely understood. In this study, we compared the composition of sugars and amino acids in the phloem sap of uninfected and TYLCCNV‐infected tobacco plants with or without whiteflies feeding on the plants. No significant differences were detected in terms of amino acid profiles, percentage of essential amino acids, and sugars:amino acids ratio. However, whiteflies feeding on TYLCCNV‐infected plants excreted comparatively a lower percentage of amino acids, especially essential amino acids, or proportionally a higher level of sugars than those feeding on uninfected plants, suggesting that whiteflies feeding on virus‐infected plants are able to achieve a more balanced nutritional assimilation. We also compared the honeydew excreted by viruliferous and non‐viruliferous whiteflies feeding on cotton [Gossypium hirsutum L. (Malvaceae)], a non‐host plant for TYLCCNV, to test the direct effects of the virus on whiteflies. Although the amino acids profiles in honeydew were similar between viruliferous and non‐viruliferous whiteflies, the sugars:amino acids ratio in honeydew excreted by viruliferous whiteflies was lower than that of non‐viruliferous whiteflies, suggesting that the viruliferous whiteflies assimilated a more imbalanced nutrition with proportionally more sugar. Taken together, our data indicate that although a plant virus may exert negative direct effects on its vector, feeding by the vector on virus‐infected plants may improve nutritional assimilation and consequently performance of the vector.

Embryogenic calli of Festuca arundinacea were transformed with the Agrobacterium tumefaciens isopentenyl transferase (ipt) gene driven by a maize ubiquitin promoter. Tillering ability, levels of chlorophyll a and b, and cold tolerance were greatly increased in the transgenic turfgrass, which resulted in the plants remaining more vigorous and staying green longer under lower temperatures.