Silencing of odorant binding protein gene AlinOBP4 by RNAi induces declining electrophysiological responses of Adelphocoris lineolatus to six semiochemicals

Odorant binding proteins （OBPs） are believed to be important for transporting semiochemicals through the aqueous sensillar lymph to the olfactory receptor cells within the insect antennal sensilla. Here, we injected AlinOBP4-siRNA into the conjunctivum between prothorax and mesothorax of the lucerne plant bug, Adelphocoris lineolatus and evaluated the silencing of AlinOBP4 by reverse transcription polymerase chain reaction （RT-PCR） analysis, quantitative real-time PCR （qPCR） test and electroantennogram （EAG） assay. The combination of RT-PCR and qPCR analyses revealed that the levels of mes- senger RNA transcript were significantly reduced ~95% in AlinOBP4-siRNA-treated A. lineolatus males and ~75% in RNAi-treated females within 48 hours. It was found that there are different EAG responses between male and female bugs when the AlinOBP4 gene was silenced by RNAi. The EAGs of A. lineolatus to two plant volatiles, tride- canal and hexyl alcohol, were reduced 9.09% and 79.45% in RNAi-treated males, 62.08% and 62.08% in RNAi-treated females compared to the controls, separately. Antennae of RNAi-treated bugs showed significantly lower electrophysiological responses to four sex pheromone analogs, butyl butanoate, 1-hexyl butyrate, （E）-2-hexenyl butyrate and hexyl hexanoate. The EAG recordings were reduced 35.43%, 35.24%, 39.96% and 78.47% in RNAi-treated males and 64.52%, 18.13%, 36.88% and 49.52% in RNAi-treated females, respectively. The results suggested that AlinOBP4 might play dual-roles in the identifi- cation of plant volatiles and sex pheromones. It was suspected that AlinOBP4 may have different functions in odor perception between male and female A. lineolatus.

Behavioral responses of potato tuber moth (Phthorimaea operculella) to tobacco plant volatiles

Potato tuber moth(PTM)Phthorimaea operculella,also known as tobacco splitworm,is an important pest of tobacco plants.The knowledge on the interaction of tobacco plant volatiles and PTM behavior is limited.To clarify the effect of tobacco plant volatiles on the orientation and oviposition behaviors of PTM and to identify potential compounds for PTM control,tobacco plant volatiles were collected by headspace collection method,and volatile compounds were identified by gas chromatography-mass spectrometry.Thirteen electrophysiological active compounds were screened by employing coupled gas chromatography-electroantennogram detection and from which nine available compounds were further verified by electroantennogram recording.cis-3-Hexen-1-ol showed significant attractant effect on the orientation behaviors of both male and female moths.Nonanal and decanal could only attract females,while octanal exhibited repellent effect on males.Oviposition selection experiment indicated that nonanal,decanal,decane and methyl hexadecanoate could stimulate the gravid females to lay more eggs,while octanal and 2,6-bis(1,1-dimethylenthyl)-4-methyl phenol inhibited their oviposition.Our study added more compounds to the list that could serve as potential PTM deterrents or attractants.

Biosynthesis of artemisinic acid in engineered Saccharomyces cerevisiae and its attractiveness to the mirid bug Apolygus lucorum

Artemisia annua is an important preferred host of the mirid bug Apolygus lucorum in autumn.Volatiles emitted from A.annua attract A.Iucorum.Volatile artemisinic acid of A.annua is a precursor of artemisinin that has been widely investigated in the Chinese herbal medicine field.However,little is known at this point about the biological roles of artemisinic acid in regulating the behavioral trends of A.lucorum.In this study,we collected volatiles from A.annua at the seedling stage by using headspace solid phase microextraction(HS-SPME).Gas chromatography-mass spectrometry(GC-MS) analysis showed that approximately 11.03±6.00 and 238.25±121.67 ng hartemisinic acid were detected in volatile samples and milled samples,respectively.Subsequently,a key gene for artemisinic acid synthesis,the cytochrome P450 gene cyp71 av1,was expressed in engineered Saccharomyces cerevisiae to catalyze the production of artemisinic acid.After the addition of exogenous artemisinic alcohol or artemisinic aldehyde,artemisinic acid was identified as the product of the expressed gene.In electroantennogram(EAG) recordings,3-day-old adult A.lucorum showed significant electrophysiological responses to artemisinic alcohol,artemisinic aldehyde and artemisinic acid.Furthermore,3-day-old female bugs were significantly attracted by artemisinic acid and artemisinic alcohol at a concentration of 10 mmol L,whereas 3-day-old male bugs were attracted significantly by 10 mmol Lartemisinic acid and artemisinic aldehyde.We propose that artemisinic acid and its precursors could be used as potential attractant components for the design of novel integrated pest management strategies to control A.lucorum.

In vivo field recordings effectively monitor the mouse cortex and hippocampus under isoflurane anesthesia

Isoflurane is a widely used inhaled anesthetic in the clinical setting. However, the mechanism underlying its effect on consciousness is under discussion. Therefore, we investigated the effect of isoflurane on the hippocampus and cortex using an in vivo field recording approach. Our results showed that 1.3%, 0.8%, and 0.4% isoflurane exerted an inhibitory influence on the mouse hippocampus and cortex. Further, high frequency bands in the cortex and hippocampus showed greater suppression with increasing isoflurane concentration. Our findings suggest that in vivo field recordings can monitor the effect of isoflurane anesthesia on the mouse cortex and hippocampus.

Functional types of long trichoid sensilla responding to sex pheromone components in Plutella xylostella

Sex pheromones,which consist of multiple components in specific ratios pro-mote intraspecific sexual communications of insects.Plutella xylostella(L.)is a world-wide pest of cruciferous vegetables,the mating behavior of which is highly dependent on its olfactory system.Long trichoid sensilla on male antennae are the main olfactory sen-silla that can sense sex pheromones.However,the underlying mechanisms remain unclear.In this study,3 sex pheromone components from sex pheromone gland secretions of P xy-lostella female adults were identified as Z11-16:Ald,Z11-16:Ac,and Z11-16:0H in a ratio of 9.4:100:17 using gas chromatography-mass spectrometry and gas chromatography with electroantennographic detection.Electrophysiological responses of 581 and 385 long trichoid sensilla of male adults and female adults,respectively,to the 3 components were measured by single sensillum recording.Hierarchical clustering analysis showed that the long trichoid sensilla were of 6 different types.In the male antennae,52.32%,5.51%,and 1.89%of the sensilla responded to Z11-16:Ald,Z11-16:Ac,and Z11-16:0H,which are named as A type,B type,and C type sensilla,respectively;2.93%named as D type sen-silla responded to both Z11-16:Ald and Z11-16:Ac,and 0.34%named as E type sensilla were sensitive to both Z11-16:Ald and Z11-16:OH.In the female antennae,only 7.53%of long trichoid sensilla responded to the sex pheromone components,A type sensilla were 3.64%,B type and C type sensilla were both 0.52%,D type sensilla were 1.30%,and 1.56%of the sensilla responded to all 3 components,which were named as F type sen-silla.The responding long trichoid sensilla were located from the base to the terminal of the male antennae and from the base to the middle of the female antennae.The pheromone mixture(Z11-16:Ald:Z11-16:Ac:Z11-16:0H=9.4:100:17)had a weakly repellent effect on female adults of P xylostella.Our results lay the foundation for further studies on sex pheromone communications in P.xylostella.