BACKGROUND RNA interference (RNAi) has been evaluated in several insect pests as a novel strategy to be included in integrated pest management. Lepidopterans are recognized to be recalcitrant to gene silencing by RNAi. As such, double‐stranded RNA (dsRNA) delivery needs to be adjusted to assure its stability until it reaches the target gene transcript for silencing. Gene silencing by RNAi offers the potential to be used in the control of Tuta absoluta (Meyrick), one of the main insect pests of tomato (Solanum lycopersicum) worldwide. Here, we tested the delivery of dsRNA expressed in Escherichia coli HT115(DE3) and supplied to larvae in an artificial diet by screening target genes for silencing. We tested six target genes: juvenile hormone inducible protein (JHP); juvenile hormone epoxide hydrolase protein (JHEH); ecdysteroid 25‐hydroxylase (PHM); chitin synthase A (CHI); carboxylesterase (COE); and arginine kinase (AK). RESULTS Based on larval mortality, the duration of the larval stage in days, pupal weight, and the accumulation of the target gene transcript, we demonstrated the efficacy of bacterial dsRNA delivery for the functional effects on larval development. Providing dsRNA targeted to JHP, CHI, COE and AK by bacteria led to a significant decrease in transcript accumulation and an increase in larval mortality. CONCLUSION Bacteria expressing dsRNA targeting essential T. absoluta genes supplied in artificial diet are efficient to screen RNAi target‐genes. The oral delivery of dsRNA by bacteria is a novel potential alternative for the control of T. absoluta based on RNAi. © 2019 Society of Chemical Industry

Summary This study aimed to enumerate and identify lactic acid bacteria and Enterobacteriaceae from spoiled and nonspoiled chilled vacuum‐packaged beef and determine their potential to cause blown pack spoilage. These microbial groups were also enumerated in nonspoiled samples and detected in abattoir samples. The potential of isolates to cause ‘blown pack’ spoilage of vacuum‐packaged beef stored at chilled temperature (4 °C) and abuse temperature (15 °C) was investigated. Populations of lactic acid bacteria in exudate of spoiled and nonspoiled samples were not significantly different (P > 0.05), whereas the number of lactic acid bacteria on the surface was significantly higher (P < 0.05) in spoiled samples as compared to nonspoiled samples. The population of Enterobacteriaceae species in exudate and on the surface of samples were significantly higher (P < 0.05) in spoiled packs in comparison with nonspoiled packs. Results of the deterioration potential showed that ‘blown pack’ spoilage was noticeable after 7 days at 15 °C and after 6 weeks at 4 °C for samples inoculated with Hafnia alvei.