Control of larval-pupal-adult molt in the moth Sesamia nonagrioides by juvenile hormone and ecdysteroids

Response of Chrysoperla nipponensis (Okamoto) (Neuroptera: Chrysopidae) Under Long and Short Photoperiods

Photoperiod is an important factor influencing many biological processes including population dynamics of many insect species in temperate zones. To determine the population response of Chrysoperla nipponensis under altered conditions (high temperature and short photoperiod) and to test whether the short photoperiod was suitable for artificial storage, the life table data of were collected at 25 °C under a long photoperiod, 15:9 h (L:D), and a short photoperiod, 9:15 h (L:D) and analyzed using the age-stage, two-sex life table approach. We found that developed faster under long photoperiod than under the short photoperiod. The shorter developmental time, higher fecundity, and higher proportion of females found during the long photoperiod resulted in higher intrinsic and net reproductive rates, but a shorter mean generation time and life expectancy compared to those reared during the short photoperiod. Individuals reared under the short photoperiod also had a high reproductive value. Population projection demonstrated that reared at long photoperiod would complete four generations in 150 d, while reared under short photoperiod would just be entering the second generation. Our results demonstrated that the different fitness values obtained for individuals by varying photoperiod lengths, were readily distinguishable when using the age-stage, two-sex life table.

Dynamic expression of miRNAs across immature and adult stages of the malaria mosquito Anopheles stephensi

Background

MicroRNAs are small non-coding RNAs that are involved in various biological processes including insect development. Anopheles stephensi serves as primary vector of malaria parasite in Asia and exhibits holometabolous life cycle that involves four different stages of development. Regulation and role of mosquito miRNAs during various stages of mosquito development remain largely unknown.

Methods

High throughput small RNA sequencing was employed for identification and profiling of miRNAs across immature and adult stages of malaria vector, which were further validated using Northern hybridization and real time PCR. Target prediction and pathway analysis was carried out to understand the role of regulated miRNAs in insect development. Degradome sequencing was employed to identify cleaved targets of some regulated miRNAs. Loss of function strategy was employed for miR-989 to understand its probable role in female reproductive process.

Results

Small RNA sequencing and data analysis revealed 111 and 14 known and novel miRNAs respectively across all stages of Anopheles stephensi. Nine miRNAs showed gender specific regulation across different stages of mosquito development. Analysis of miRNAs revealed regulation of 24 and 26 miRNAs across different stages of male and female mosquito development respectively. mRNA targets and significant pathways targeted by regulated miRNAs were identified for each stage of mosquito development. Degradome sequencing revealed twenty nine cleaved targets of insect miRNAs. MicroRNA-989 showed significant up-regulation in the adult female as compared to adult male mosquito. Knockdown of miR-989 expression in adult female using miRNA specific antagomir affected targets playing roles in protein binding, proteolysis and nucleic acid binding in ovary tissue of female mosquito post blood feeding.

Conclusions

This is the first comprehensive effort to understand regulation of Anopheles stephensi miRNAs across developmental stages of male and female mosquito. Preliminary role of regulated miRNAs in mosquito development was revealed by target prediction and pathway analysis. MicroRNA-989 emerged to have important roles in adult female mosquitoes showing significant up-regulation which was further studied using miR-989 specific antagomir. This study provides insights into mosquito development and reproductive process and has implications for effective control of mosquito population required for reducing spread of mosquito-borne infectious diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-015-0772-y) contains supplementary material, which is available to authorized users.

Comparative analysis of hemolymph proteome maps in diapausing and non-diapausing larvae of Sesamia nonagrioides

Background

Sesamia nonagrioides is a noctuid that feeds on maize, sugar cane and sorghum in North Africa and Southern Europe. Larvae reared under long day conditions pupate after 5 or 6 larval instars, whereas larvae reared under short day conditions enter diapause and undergo up to 12 molts before dying or pupating. To better understand the mechanism of larval development and diapause, we identified proteins with different expressions in the sixth instar of diapausing and non-diapausing larvae.

Results

A total of 52 differentially regulated proteins were detected in the hemolymph of the diapausing or non-diapausing larvae at the beginning or end of the sixth instar. From these proteins, 11 were identified by mass spectrometry (MALDI-TOF MS or MALDI-TOF/TOF MS/MS): 5 were upregulated in the hemolymph of non-diapausing larvae and 6 in the hemolymph of the diapausing larvae. Interestingly, some proteins were expressed only in non-diapausing larvae but none was expressed only in the hemolymph of diapausing larvae. The possible functions of some of these proteins related to diapause maintenance or to larval-pupal metamorphosis are discussed.

Conclusions

The 2-DE proteomic map of S. nonagrioides hemolymph shows differential protein expression in diapausing and non-diapausing larvae. Some proteins that showed higher expression in the diapausing larvae at the end of the sixth instar could be involved in JH level maintenance thus in the diapause status maintenance. On the contrary, other proteins that showed the highest expression or that were expressed only in the non-diapausing larvae could be involved in larval-pupal metamorphosis.

UHPLC-MS analysis of juvenile hormone II in Mediterranean corn borer (Sesamia nonagrioides) hemolymph using various ionization techniques

The juvenile hormones (JHs) have been considered the most versatile hormones in the animal kingdom. JH-II is the most abundant JH in Sesamia nonagrioides, important maize pests in the Mediterranean basin. This study compared the sensitivities and matrix effects of four ionization modes on analyzing JH-II in S. nonagrioides hemolymph using ultrahigh-performance liquid chromatography-mass spectrometry (UHPLC-MS) in single ion monitoring (SIM) mode. The ionization techniques tested were electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), atmospheric pressure photoionization (APPI), and APPI with the lamp turned off, which corresponds to atmospheric pressure thermospray ionization (APTSI). ESI was discarded because of the high matrix effect. APPI was discarded because the correlation responses between solvent and matrix on the instrumental quality parameters were worse than those for APTSI and APCI. In our analytical conditions, APCI has shown the best validation parameter values. APCI ionization is widely available in instrumental laboratories.