Sensitivity of polyphagous(Plodia interpunctella)and stenophagous(Ephestia kuehniella)storage moths to residual insecticides:effect of formulation and larval age

Pyralid moths,Ephestia kuehniella and Plodia interpunctella,are prevalent stored product pests.The insecticides are the main tool to control these moths in the stores.The data describing the response of these moths to insecticides are scarce.The lethal effect of the organophosphate,pyrethroid,and halogenated-pyrrole on moths larvae were compared in laboratory test.The hypothesis was that the very polyphagous P.inter-punctella would have generally higher insecticide tolerance than that of the stenophagous E.kuehniella.Different insecticide concentrations were applied onto the inner surface of glass tube vials.Ten larvae of 14 or 21 d old of E.kuehniella and 7 or 14 d old of P.interpunctella were used by treatment.The larval mortality was checked after 24 h of exposure.The mortality was significantly influenced by age of larvae and the groups of chemicals.No differences among the efficacies of the tested formulations with identical active compounds were found,except significant different mortality of E.kuehniella on deltamethrin formulations.A comparison of analytical standards showed that P.interpunctella was less susceptible to the active ingredient pirimiphos-methyl than E.kuehniella,while E.kuehniella was less susceptible to deltamethrin than P.interpunctella.No differences between the two species were observed for chlorfenapyr.We therefore rejected the hypothesis that polyphagy/stenophagy can be a general predictor of insecticide tolerance in the two tested storage moths.The most important finding for effective use was that the young larvae of both species were more susceptible to tested insecticides than older larvae.

Do the microorganisms from laboratory culture spent growth medium affect house dust mite fitness and microbiome composition?

The interaction of house dust mites(HDM)and microorganisms is the key factor in the survival of these mites in human-made environments.Spent growth medium(SPGM)provides the rest of the dict,along with dead mite bodies and microorganisms.SPGM represents a source of microorganisms for the recolonization of mite food and the mite digestive tract.An experiment was performed to observe how adding SPGM to the HDM diet affects HDM population growth,the microbiome composition and the microbial respiration in microcosms.We analyzed American house dust mite(Dermatophagoides farinae)and European house dust mite(Dermatophagoides pleronyssinus)originating from control diets and diets treated with an extract of SPGM from 1-and 3-month-old mite cultures.The microbiome was described using 16S and 18S barcode sequencing.The composition of the bacterial and fiungal microbiomes differed between the HDM species,but the SPGM treatment influenced only the bacterial profile of D.farinae.In the D.farinae microbiome of specimens on SPGM-treated dicts compared to those of the control situation,the Lactobacillus profile decreased,while the Candinium,Staphylococ-cus,Acinetobacter,and Sphingomonas profiles increased.The addition of SPGM extract decreased the microbial respiration in the microcosms with and without mites in almost all cascs.Adding SPGM did not influence the population growth of D.farinae,but it had a variable effect on D.pteronyssimus.The results indicated that the HDM are marginally influenced by the microorganisms in their feces.