The specificity of the double-stranded RNA (dsRNA) used in the RNA interference (RNAi) technique is crucial for the success of sequence-specific gene silencing.  Currently, RNAi-mediated insect control is a trending research topic.  However, the off-target effects of the dsRNA in RNAi are a major concern.  In this study, the dsHvβ´COPI (coat protein complex I, β´ subunit)-treated and untreated transcriptomes of the 28-spotted potato lady beetle (Henosepilachna vigintioctopunctata) were compared to understand its off-target gene silencing effects.  The RNA-seq results revealed that 63 and 44 differentially expressed genes (DEGs) were upregulated and downregulated, respectively, in the dsHvβ´COPI treated group as compared with the control.  Validation of the differential expressions of some selected DEGs via reverse transcription-quantitative PCR (RT-qPCR) analysis confirmed the reliability of the transcriptome analysis results.  Further downstream analysis revealed that there were no genes homologous with Hvβ´COPI in H. vigintioctopunctata.  Additionally, no genes with a >11 bp continuous match with dsHvβ´COPI were found in the H. vigintioctopunctata transcriptome.  Six genes (Hvcitron, Hvhelicase, Hvtransposase, Hvserine, Hvdynein, and HvE3 ubiquitin) were selected to examine the off-target activity of dsHvβ´COPI based on their potential involvement in various H. vigintioctopunctata metabolic pathways.  The severity of silencing these six off-target genes was evaluated by employing RNAi.  The RNAi results confirmed the downregulation of the expression of all six genes, although there was no significant lethality.  The findings of this study will be helpful in the risk analysis of future RNAi-mediated pest control experiments.

The present study reports the sublethal effects of the entomopathogenic fungus, Aschersonia aleyrodis (Webber) on Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae).  A fungal suspension of A. aleyrodis isolate Aa005 containing 1×10⁷ conidia mL^–1 was sprayed against B. tabaci on eggplant leaves under greenhouse conditions.  The effects of fungal application on survival as well as life table parameters of the whitefly were observed at different post inoculation periods.  The results indicated that A. aleyrodis can significantly affect the survival of 1st, 2nd, and 3rd nymphal instars of B. tabaci.  Developmental periods of different instar nymphs were not affected by fungal application.  A. aleyrodis spores persisted well and significantly affected the survivorship of young instar nymphs of B. tabaci at different post incubation periods.  Life table results suggested that A. aleyrodis has no impact on general fecundity and longevity of B. tabaci.  When the pathogen was exposed to the open environment and maintained for a relatively longer period, a reduction in the reproductive rate and intrinsic rate of increase was caused by the fungal spores, though the sublethal effects were not as good as the control treatment.  The results suggest that the ability of spores to suppress an increase in whitefly population persists well after incubation of spores to the external environment (up to 9 days).  

The sweetpotato whitefly Bemisia tabaci (Homoptera: Aleyrodidae) is a destructive pest of agriculture and horticulture worldwide. Recent phylogenetic analysis using mitochondrial cytochrome oxidase 1 sequences indicates that this whitefly is a species complex including at least 24 morphologically indistinguishable but genetically distinct cryptic species. In this study, the inter-species crosses of Middle East-Asia Minor 1 (MEAM1), Mediterranean (MED) and Asia II 7 cryptic species, which were referred to as B, Q and Cv biotypes before, were conducted in two different devices, leaf cages (7 cm3) and cylinder cages (280 cm3), and at three temperatures of 22, 30 and 38°C. Results indicated that no female progeny were produced in the reciprocal cross between MEAM1×Asia II 7, between MED×Asia II 7 cryptic species neither in leaf cage nor in cylinder cages, while 0.81 and 1.37% of females in the offspring were recorded in the reciprocal cross between MEAM1×MED in leaf cage experiments. Approximately 0.95-0.98% female progeny were recorded in the reciprocal cross between MEAM1×MED at 30°C, 0.77% female progeny were recorded in the single cross direction between MEAM1 × MED at 22°C, and no female progeny were found in their reciprocal cross at 38°C in leaf cage. Our findings indicated that neither space dimension nor temperature have a significant effect on the hybridization of different B. tabaci cryptic species.

The blue gum chalcid, Leptocybe invasa Fisher & La Salle, invaded China in 2007 and has subsequently caused substantial damage to eucalyptus trees. In the current paper, we investigated the susceptibility of 10 Eucalyptus spp. and Eucahetus dunnii to L. invasa in the field, determined the density of galls as well as the gall volume on these tree species, and monitored the population dynamics of wasps in Hainan and Guangdong provinces of China. The order of susceptibility to L. invasa was Eucalyptus urophylla×Eucalyptus camaldulensis>E. urophylla (coppices)>Eucalyptus exserta> Eucalyptus grandis×E. urophylla in Hainan, and Eucalyptus propinqua>Eucalyptus saligna>E. exserta>Eucalyptus microcorys>Eucahetus dunnii>E. camaldulensis>Eucalyptus tereticornis>Eucalyptus robust in Guangdong, China. Although L. invasa generally damages the midribs and petioles of young leaves and the tender bark of twigs of eucalyptus, galls were not observed on leaves of E. microcorys, E. camaldulensis, or E. dunnii. Gall volume significantly differed among the tree species, and gall volume and wasp number were positively correlated. In Dongfang, Hainan Province, the overwintering period of L. invasa emergencing through the year was from the end of December to March of the next year, and the number of population was the greatest on E. urophylla×E. camaldulensis, and the smallest on E. grandis×E. urophylla. In Guangzhou, Guangdong Province, L. invasa hardly emerged in winter from December to June of the next year, and the population was the greatest on E. propinqua, and the smallest on E. microcorys.