Most GmPAP genes are probably involved in P acquisition and recycling in plants. Also we provide the first evidence that some members of the GmPAP gene family are possibly involved in the response of plants to symbiosis with rhizobia or arbuscular mycorrhizal fungi under P-limited conditions.

Insects must undergo ecdysis for successful development and growth, and the ecdysis triggering hormone (ETH), released by the Inka cells, is a master hormone in this process. In this study, we determined the sequence of the ETH precursor and receptors in an agriculturally important pest insect, the oriental fruit fly Bactrocera dorsalis (Hendel). We identified two functionally distinct splice receptor isoforms: BdETH-R-A and BdETH-R-B, and when expressed in Chinese hamster ovary (CHO-WTA11) cells, they exhibited a high sensitivity to the two mature peptides BdETH1 and BdETH2. The BdETH transcript was detected in the tracheal tissue of the larvae. Inka cells were identified with immunohistochemical antibody staining against Drosophila melanogaster ETH1, and in situ hybridization with specific DNA probes. Selective RNA silencing of BdETH or BdETH-R-A, but not of BdETH-R-B, caused developmental failure at ecdysis. The dsRNA-treated larvae displayed tracheal defects and could not shed the old cuticle followed by death. Our results demonstrated that BdETH, via activation of BdETH-R-A but not ETH-R-B, plays an essential role in regulating the process of larva-larva ecdysis in B. dorsalis.

BACKGROUND Insect Capability neuropeptides (CAP2b/CAPA‐PKs) play a critical role in modulating different physiologies and behavior in insects. In a previous proof‐of‐concept study, the CAP2b analogues 1895 (2Abf‐Suc‐FGPRLamide) and 2129 (2Abf‐Suc‐ATPRIamide) were reported to reduce aphid fitness when administered by injection. In the current study, the insecticidal efficacy of 1895 and 2129 on the peach potato aphid Myzus persicae was analyzed by topical application, simulating a spray application scenario in the field. Additionally, the selectivity of the tested analogues was evaluated against a selection of beneficial insects, namely three natural enemies (Adalia bipunctata, Chrysoperla carnea and Nasonia vitripennis) and a pollinator (Bombus terrestris). RESULTS Within 3–5 days post topical exposure of aphids to 1895, higher mortality (33%) was observed, as was the case for the treatment with 2129 (17%) and the mixture of 1895 + 2129 (47%) compared to the control (3%). 1895 and the mix 1895 + 2129 showed the strongest and comparable insecticidal effects. Additionally, surviving aphids treated with 1895 showed a reduction in total lifetime reproduction (GRR) of 30%, 19% with 2129 and 39% with the mix 1895 + 2129. Of interest from a biosafety perspective is that by using the same delivery method and dose, no significant effects on survival, weight increase and food intake was observed for the representative natural enemies and the pollinator. CONCLUSION This study highlights the potential of exploiting CAP2b analogues such as 1895 (core structure FGPRL) as aphicides. Additionally, the CAP2b analogues used in this study were selective as they showed no effects when applied on four representative beneficial insects.

We collected Ectobiidae cockroach specimens from 44 locations in the south of the Yangtze valley. We obtained 297 COI sequences specimens and carried out phylogenetic and divergence dating analyses, as well as species delimitation analysis using a General Mixed Yule Coalescent (GMYC) framework. The intraspecific and interspecific sequence divergence in Ectobiidae cockroaches ranged from 0.0 to 7.0% and 4.6 to 30.8%, respectively. GMYC analysis resulted in 53 (confidence interval: 37–65) entities (likelihood ratio = 103.63) including 14 downloaded species. The COI GMYC groups partly corresponded to the ectobiid species and 52 ectobiid species were delimited successfully based on the combination of GMYC result with morphological information. We used the molecular data and 6 cockroach fossil calibrations to obtain a preliminary estimate of the timescale of ectobiid evolution. The major subfamilies in the group were found to have diverged between ~125–110 Ma, and morphospecies pairs were found to have diverged ~10 or more Ma.

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Corazonin (Crz) is a neuropeptide hormone, but also a neuropeptide modulator that is internally released within the CNS, and it has a widespread distribution in insects with diverse physiological functions. Here, we identified and cloned the cDNAs of Bactrocera dorsalis that encode Crz and its receptor CrzR. Mature BdCrz has 11 residues with a unique Ser 11 substitution (instead of the typical Asn) and a His in the evolutionary variable position 7. The BdCrzR cDNA encodes a putative protein of 608 amino acids with 7 putative transmembrane domains, typical for the structure of G-protein-coupled receptors. When expressed in Chinese hamster ovary (CHO) cells, the BdCrzR exhibited a high sensitivity and selectivity for Crz (EC 50 ≈ 52.5 nM). With qPCR, the developmental stage and tissue-specific expression profiles in B. dorsalis demonstrated that both BdCrz and BdCrzR were highly expressed in the larval stage, and BdCrzR peaked in 2-day-old 3rd-instar larvae, suggesting that the BdCrzR may play an important role in the larval-pupal transition behavior. Immunochemical localization confirmed the production of Crz in the central nervous system (CNS), specifically by a group of three neurons in the dorso-lateral protocerebrum and eight pairs of lateral neurons in the ventral nerve cord. qPCR analysis located the BdCrzR in both the CNS and epitracheal gland, containing the Inka cells. Importantly, dsRNA- BdCrzR -mediated gene-silencing caused a delay in larval-pupal transition and pupariation, and this phenomenon agreed with a delayed expression of tyrosine hydroxylase and dopa-decarboxylase genes. We speculate that CrzR-silencing blocked dopamine synthesis, resulting in the inhibition of pupariation and cuticular melanization. Finally, injection of Crz in head-ligated larvae could rescue the effects. These findings provide a new insight into the roles of Crz signaling pathway components in B. dorsalis and support an important role of CrzR in larval-pupal transition and pupariation behavior.

Initially, natalisin (NTL) was identified from three holometabolous insect species, Drosophila melanogaster, Tribolium castaneum and Bombyx mori, and was documented to regulate reproductive behaviours in D. melanogaster and T. castaneum. In this study, we report the sequences of the NTL precursor and its receptor (NTLR) from an important agricultural pest, Bactrocera dorsalis (Hendel). NTLR is a typical G-protein coupled receptor and phylogenetic analysis showed that B. dorsalis NTLR was closely related to insect natalisin receptors from other species. A functional assay of NTLR transiently expressed in Chinese hamster ovary cells showed that it was activated by putative natalisin mature peptides in a concentration-dependent manner, with 50% effective concentrations (EC ) at nanomolar or micromolar levels. As indicated by quantitative real-time PCR, both NTL and NTLR had the highest expression in the central nervous system of B. dorsalis compared with the other tested tissues. Three pairs of adult brain neurones of B. dorsalis were identified with immunohistochemical antibody staining against D. melanogaster NTL4, and in situ hybridization with specific DNA probes. Moreover, RNA interference mediated by double-stranded RNA injection in adults provided evidence for the important roles of NTL in regulating both male and female mating frequencies in this fly.