Invasive sequence and ecological niche of main insect borers of Larix gmelinii forest in Aershan, Inner Mongolia

After the outbreak of Dendrolimus superans Buter in 2002, many insect borers quickly invaded larch （Larix gmelinii Rupr.） forests in the Aershan of Inner Mongolia. Methods involved included setting sample plots, collecting adults in iron traps and measuring areas of galleries to study the invasive sequence, their ecological niche and the extent of the different effects by the main insect borers to their hosts. The results showed that the damage of D. superans weakened L. gmelinii, first Ips subelongatus Motschulsky invaded, followed by Acanthocinus carinulatus Gebler, Monochamus urussovi Fisher and M. sutor L. After the outbreak of D. superans, the average density of longhorn beetles per L. gmelinii tree increased. The ecological niche of Ips subelongatus stretches almost from the base to the top of the trunk. The number of insects in older stands of L. gmelinii is larger than those in middle aged stands. They do not damage healthy trees of L. gmelinii. The ecological niche of A. carinulatus is higher in dead L. gmelinii trees than in weak ones. The degree of damage is directly proportional with age and depth of bark. M. urussovi mainly damages trunks below 4 m in weak trees; in dead trees they can do damage up to 6 m in height. M. sutor mainly damages trunks below 5 m in weak L. gmelinii trees; in dead trees they cause damage up to 7 m. Again, the degree of damage is directly proportional with age. None of the three species of longhorn beetles damage healthy L. gmelinii and younger trees. Among the main insect borers, the degree of damage caused by I. subelongatus is more serious than that of other insects.

Range expansion of the invasive cotton mealybug, Phenacoccus solenopsis Tinsley: An increasing threat to agricultural and horticultural crops in China

The globally invasive cotton mealybug Phenacoccus solenopsis Tinsley,has recently invaded several Chinese regions,and continues to expand its range.This mealybug is a polyphagous insect pest,with at least 200 host plants from 63 families,including cotton,food crops,fruits,ornamental plants,tobacco,and vegetables.Here,we describe the first finding of P.solenopsis in Shandong Province,and investigate the abundances of its natural enemies(predator Coccinella septempunctata L.and parasitoid Aenasius bambawalei Hayat).All three species were detected from ornamental and weed species in Linyi,Shandong,in September 2018,and were positively identified using DNA barcoding.BLAST analysis revealed significant identity(99.38-100%) between sequences of P.solenopsis obtained in this study and those published in the past.This invasive pest represents a major potential threat to agri-horticulture in Shandong,which is a key province of China for production and export of many vegetables,flowers,fruits,and other crops.This mealybug species has a wide range of potential distribution in Shandong and is easily dispersed with agricultural and horticultural transport products.Further monitoring and management strategies are required to limit the spread of this pest species.

Metagenomic analysis reveals changes of the Drosophila suzukii microbiota in the newly colonized regions

The spotted wing drosophila, Drosophila suzula＇i （Matsumura） （Diptera： Drosophilidae） is a highly polyphagous pest of a wide variety of wild or cultivated berry and stone fruit. Originating from Southeast Asia, it has recently invaded a wide range of regions in Europe and North America. It is well known that insect microbiotas may significantly influence several aspects of the host biology and play an important role in invasive species introduction into new areas. However, in spite of the great economic im- portance of D. suzukii, a limited attention has been given so far to its microbiota. In this study, we present the first in-depth characterization of gut bacterial diversity from field （native and invasive range） and lab-reared populations of this insect. The gut bacterial communities of field insects were dominated, regardless of their origin, by 2 families of the phylum Proteobacteria： Acetobacteraceae and Enterobacteriaceae, while Firmicutes, mainly represented by the family Staphylococcaceae, prevailed in lab-reared population. Locality was the most significant factor in shaping the microbiota of wild flies. More- over, a negative correlation between diversity and abundance of Enterobacteriaceae and the time elapsed since the establishment of D. suzukii in a new region was observed. Altogether our results indicate that habitat, food resources as well as the colonization phase of a new region contribute to shape the bacterial communities of the invasive species which, in turn, by evolving more quickly, could influence host adaptation in a new environment.

How behavioral plasticity enables foraging under changing environmental conditions in the social wasp Vespula germanica (Hymenoptera: Vespidae)

The foraging strategy at abundant resources of the social wasp Vespula germanica includes scanning in the direction of the nest while memorizing resource-specific landmarks and contextual cues.In the present study,we sought to explore wasps'behavioral plasticity on foraging trips to resources whose location and composition changed after a single visit.We evaluated how contextual modifications of food displacement and replacements 60 cm apart from the original site,affect re-orientation for re-finding previously memorized food resources.The results showed that wasps detected and collected the resource faster when more changes were introduced on the following visit.If returning foragers discovered several modifications on both the location and the kind of resource,they collected food more rapidly from the displaced dish,than if only a single parameter in the environment had been changed.These findings illustrate the grade of behavioral plasticity in V.germanica while foraging on abundant resources,which may contribute to the understanding of the prodigious invasive success of this species in anthropized environments.