Genetic relationships of introduced Colorado potato beetle Leptinotarsa decemlineata populations in Xinjiang, China

The Colorado potato beetle （CPB）, Leptinotarsa decemlineata （Say）, is an infamous invasive species worldwide that aggressively attacks potato and other Solanaceae crops. CPB was first found in China in 1993 and has since spread across 2.77 × 105 km2 in Xinjiang Uygur Autonomous Region. To better understand genetic variation and migration patterns, we used seven polymorphic microsatellite loci to elucidate the genetic relationships and gene flow among 10 CPB populations across Xinjiang. （i） Overall low levels of genetic diversity were detected on the entire population in Xinjiang but most of the diversity was retained among populations during invasion. （ii） The mean pairwise FST was low （0.071 ± 0.043） among populations. The genetic differentiation was little （pairwise FST 0.038 ± 0.016） between the five interior populations （Wusu, Urumqi, Jimsar, Qitai and Mulei） and Tacheng population. The six populations might come from the same genetic group via Bayesian clustering and were closely related on a neighbor-joining tree. Combining the history data, the five interior populations may have originated from Tacheng. （iii） Gene flow was frequent, especially among the five interior populations. Individuals from the interior populations could be assigned to Tacheng at higher probabilities （means 0.518 ± 0.127） than vice versa （means 0.328 ± 0.074）, suggesting that the beetle population has spread from the border to the interior in Xinjiang.

Preparation of Nylon MXD6/EG/CNTs Ternary Composites with Excellent Thermal Conductivity and Electromagnetic Interference Shielding Effectiveness

In this article, hybrid fillers with different dimensions, namely, 2-dimensional（2-D） expanded graphite（EG） and 1-dimensional（1-D） multi-walled carbon nanotubes（CNTs）, were added to aromatic nylon MXD6 matrix via melt-blending, to enhance its thermal and electrical conductivity as well as electromagnetic interference shielding effectiveness（EMI SE）. For ternary composites of MXD6/EG/CNTs, the electrical conductivity reaches up nine orders of magnitude higher compared to that of the neat MXD6 sample, which turned the polymer-based composites from an insulator to a conductor, and the thermal conductivity has been enhanced by 477% compared with that of neat MXD6 sample. Meanwhile, the EMI SE of ternary composite reaches ~50 d B at the overall filler loading of only 18 wt%. This work can provide guidance for the preparation of polymer composites with excellent thermal and electrical conductivity via using hybrid filler.

Use of ryegrass strips to enhance biological control of aphids by ladybirds in wheat fields

Non-crop habitats may play a vital role in conservation biological control. This study tested the effect of ryegrass （Lolium multiflorum L.） strips on aphid and la- dybird populations in adjacent winter wheat fields. The field experiment was conducted in three ryegrass-margin wheat plots and three control plots in 2010 in North China. In spring, the same aphid species, Sitobion miscanthi （Takahashi）, was found in both the ryegrass strips and wheat plots. The population density of ladybirds in the ryegrass strips （3.5 4- 0.9/m2） was significantly higher than in the wheat plots （1.5 4- 0.5/m2）. We cut the ryegrass, forcing the ladybirds to migrate to the wheat fields. Three and eight days after cutting the ryegrass, the aphid numbers in the ryegrass-margin wheat plots decreased significantly： they were 19.9% and 53.6%, respectively, lower than in control plots. In the early period of ladybird population development, the percentage of larvae was greater in the ryegrass-margin wheat plots than in controls, and the peak number of pupae in the ryegrass-margin wheat plots occurred 5 days earlier than in the control plots. The results suggest that ryegrass strips may promote the development of ladybird populations. Cutting ryegrass can manipulate ladybirds to enhance biological aphid control in wheat fields. The efficiency of this management approach is discussed.

The endoparasitoid Psyllaephagus arenarius benefits from ectoparasitic venom via multiparasitism with the ectoparasitoid Tamarixia lyciumi

As solitary nymphal parasitoids of Pamtrioza sinica,the ectoparasitoid Tamarixia lyciumi and the endoparasitoid Psyllaephagus arenarius act as effective biocontrol agents.Thus,it is necessary to facilitate mass productions of both species.Despite showing an excellent parasitic ability,Ps.arenarius is often trapped fatally inside 5th-instar nymphs of Pa.sinica due to strong host immunity.To improve the emergence rate of Ps.arenarius,we evaluated whether Ps.arenarius could utilize T.lyciumi venom via multiparasitism,so the parasitism characteristics of both species were examined between separate-existence(monoparasitism only)and co-existence(mono-and multiparasitism)systems.Further,the parasitism characteristics of Ps.arenarius on venom-injected hosts with/without T.lyciumi eggs were tested to further identify the facilitator.The results showed the parasitism rate of T.lyciumi was increased while that of Ps.arenarius did not change from separate-existence to co-existence systems.The intrinsic performances of two species in monoparasitism did not differ between separate-and co-existence systems.From monoparasitism(separate-existence)to multiparasitism(co-existence),no differences were detected in the intrinsic performances of T.lyciumi,but those of Ps.arenarius were greatly improved.After T.lyciumi venom injection,the parasitism characteristics of Ps.arenarius did not differ between venom-injected hosts with T.lyciumi eggs and those without,further indicating Ps.arenarius benefited from the venom of T.lyciumi females rather than T.lyciumi egg/larval secretions.Instead of negative effects,multiparasitism with ectoparasitoids improves endoparasitoids due to ectoparasitic venom.The study increases host resource utilization and provides creative ways for mass production of endoparasitoids.