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.

Analysis of expressed sequence tags （ESTs） from a normalized cDNA library and isolation of EST simple sequence repeats from the invasive cotton mealybug Phenacoccus solenopsis

The cotton mealybug, Phenacoccus solenopsis Tinsley, is a serious and invasive pest. At present, genetic resources for studying P. solenopsis are limited, and this negatively affects genetic research on the organism and, consequently, translational work to improve management of this pest. In the present study, expressed sequence tags （ESTs） were analyzed from a normalized complementary DNA library of/？. solenopsis. In addition, EST-derived microsatellite loci （also known as simple sequence repeats or SSRs） were isolated and characterized. A total of 1107 high-quality ESTs were acquired from the library. Clustering and assembly analysis resulted in 785 unigenes, which were classified functionally into 23 categories according to the Gene Ontology database. Seven EST-based SSR markers were developed in this study and are expected to be useful in characterizing how this invasive species was introduced, as well as providing insights into its genetic microevolution.

Preferential feeding of an anthocorid predator Blaptostethus pallescens Poppius on different stages of cotton mealybug

Blaptostethus pallescens Poppius (Heteroptera:Anthocoridae),which is amenable to mass rearing,has proved to be a potential predator of sucking pests like mites and thrips.Recently,the cotton mealybug Phenacoccus solenopsis Tinsley emerged as a serious pest on cotton in India.Laboratory studies indicated that B.pallescens could feed on the cotton mealybug.Hence,further investigations were conducted to understand the stage of the predator which is most potential and the pest stage preferred by the predator.Mature nymphs and adults of B.pallescens could predate equally well on the neonates of cotton mealybug.Young (three to four-day-old) nymphs of the predator could not feed on any stage of the cotton mealybug.Mature nymphs (seven-day-old and above) and adults could effectively predate on both young and mature cotton mealybug crawlers,though preference was more for the younger crawlers.However,nymphs and adults of B.pallescens could not predate on the adult stage of the mealybug.Different predator:pest ratios were tested in cage studies and it emerged that B.pallescens adults released against the mealybug crawlers at a ratio of 1:5 and nymphal release at 1:10 caused maximum mortality of the mealybug crawlers.Considering the fast multiplication rate of cotton mealybug and the large number of predators which have to be released to manage them,further detailed studies are necessary on utilizing B.pallescens to target the neonates and younger stages of the cotton mealybug in field conditions.

Transcriptome profile analysis of the accompanying migratory parasitic wasp Aenasius bambawalei(=Aenasius arizonensis girault)(Hymenoptera:Encyrtidae):Genes related to fertilization involved at different stage of ovary development

Age-related declines in fertilization success have been reported for a wide range of species.The fertilization of parasitic wasps is closely related to egg production and sperm storage.Aenasius bambawalei(Hymenoptera:Encyridae)is a key parasitic wasp of the important invasive mealybug Phenacoccus solenopsis(Hemiptera:Pseudococcidae).The female offspring ratio of this parasitic wasp was declined with parental age in mass rearing under laboratory conditions.To investigate the molecular mechanisms involved in the reproduction of A.bambawalei,an extensive analysis of the impact of age on transcriptome profile of mated ovaries of this wasp was performed by comparing the gene expression profiles of various maternal ages:the early stage(ES),the intermediate stage(IS),and the advanced stage(AS).In total,358 differentially expressed genes were identified,with 17.60%(63 genes)of the changes associated with greater expression in fertilization.Moreover,the expression of serine protease 47 precursor,serine protease inhibitor 3/4,glucose dehydrogenase,fatty acyl-CoA reductase 1-like,major royal jelly,and acyl-CoA delta(11)desaturase-like was detected by real-time fluorescence quantitative(RT-qPCR).The results showed that fertilization related genes exhibited a stage-specific pattern.Egg production and sperm storage genes in A.bambawalei were significantly modified in the transcriptome,providing a starting point for the genetic dissection of fertilization.

Chinese species of the genus Prochiloneurus Silvestri with description of a new species(Hymenoptera: Encyrtidae)

Four species of the genus Prochiloneurus Silvestri, belonging to the family Encyrtidae of Hymenoptera, are reported from China. Among them, P. stenopterus sp. nov., which is reared as the hyperparasitoid of Phenacoccus solenopsis Tinsley （Hemiptera： Pseudococcidae）, an invasive mealybug to China, is reported as new to science. A key of the genus is provided for the recognition of the females of Chinese species. Notes on the parasitoid and hyperparasitoid of the mealybug Phenacoccus solenopsis are provided.