Explore the vast range of titles available.

Key message

Oil palm is one of Colombia’s main agribusinesses, with more than 590,000 ha planted. The eastern palm-growing region accounts for 47% of the planted area. It is also the area affected by the Lethal Wilt disease, which has caused the eradication of more than a million palms, equivalent to 7790 ha. Haplaxius crudus is considered a vector of the causal agent of this disease, and management strategies are focused on reducing H. crudus populations in the field. However, the population parameters of the insect, which are essential for adequate control, are unknown. Therefore, it was proposed to determine the life cycle and life table parameters under semi-controlled conditions in an oil palm plantation. The life cycle was 62.7 ± 15.5 days (average ± standard deviation). The egg stage lasted 14.6 ± 0.6 days, the nymphal stage 48.1 ± 14.9, and adult longevity was 14.8 ± 8.4 days. The highest specific mortality rate (qx) was in the egg phase: 0.14. The net reproductive rate was Ro = 10.96; the generation time was T = 62.3 days, the intrinsic natural growth rate was rm = 0.03, the and finite growth rate was λ = 1.03. These results contribute to the knowledge of the population dynamics of this insect in the field and for the development of population control studies. The palm leafhopper, Haplaxius crudus, is a possible vector of the pathogen that causes the Lethal Wilt of oil palms in Colombia. This disease represents the biggest phytosanitary problem in the eastern palm zone. From 2010 to 2021, more than 7700 ha have been eradicated, with economic losses exceeding 154 million USD. Therefore, knowing the biology of this insect and its population parameters is necessary for developing population control tools. To evaluate these parameters, a cohort of 100 eggs obtained from H. crudus adults from the breeding unit established in the Campo Experimental Palmar de las Corocoras de Cenipalma in Paratebueno, Cundinamarca, was monitored to record the life cycle and the population parameters using a life table under semi-controlled conditions in an oil palm plantation. The life cycle from egg to adult was 62.7 ± 15.5 days (26.1 ± 2.9 °C; HR: 89.8 ± 14.0%). The egg stage lasted 14.6 ± 0.6 days, the nymphal stage 48.1 ± 2.8 days through five instars, and the adult longevity was 14.8 ± 8.4 days. The specific mortality rate (qx) calculated in the life table was 0.14 (for the egg stage), 0.05 (for I instar), 0.05 (for II instar), 0.03 (for III instar), 0.04 (for IV instar), and 0.07 (for V instar). The population parameters’ values were as follows: net reproductive rate Ro = 10.96; generation time T = 62.3 days, intrinsic natural growth rate rm = 0.03, and finite growth rate λ = 1.03. These results help us to understand the population dynamics of this insect in the field and for the development of population control studies.

The stolbur phytoplasma vector Hyalesthes obsoletus is generally considered as a polyphagous species associated with numerous wild and cultivated plants. However, recent research in southeastern Europe, the distribution centre of H. obsoletus and the area of most stolbur-inflicted crop diseases, points toward specific host-plant associations of the vector, indicating specific vector-based transmission routes. Here, we study the specificity of populations associated with four host-plants using mitochondrial and nuclear genetic markers, and we evaluate the evolution of host-shifts in H. obsoletus. Host-plant use was confirmed for Convolvulus arvensis, Urtica dioica, Vitex agnus-castus and Crepis foetida. Mitochondrial genetic analysis showed sympatric occurrence of three phylogenetic lineages that were ecologically delineated by host-plant preference, but were morphologically inseparable. Nuclear data supported the existence of three genetic groups (Evanno's [DELTA]K(3) = 803.72) with average genetic membership probabilities > 90%. While populations associated with C. arvensis and U. dioica form a homogenous group, populations affiliated with V. agnus-castus and C. foetida constitute two independent plant-associated lineages. The geographical signal permeating the surveyed populations indicated complex diversification processes associated with host-plant selection and likely derived from post-glacial refugia in the eastern Mediterranean. This study provides evidence for cryptic species diversification within H. obsoletus sensu lato: i) consistent mitochondrial differentiation (1.1-1.5%) among host-associated populations in syntopy and in geographically distant areas, ii) nuclear genetic variance supporting mitochondrial data, and iii) average mitochondrial genetic distances among host-associated meta-populations are comparable to the most closely related, morphologically distinguishable species, i.e., Hyalesthes thracicus (2.1-3.3%).

Background The brown planthopper (BPH) is a kind of piercing-sucking insect specific to rice, with the damage tops the list of pathogens and insects in recent years. microRNAs (miRNAs) are pivotal regulators of plant–environment interactions, while the mechanism underlying their function against insects is largely unknown. Results Here, we confirmed that OsmiR319, an ancient and conserved miRNA, negatively regulated resistance to BPHs, with overexpression of OsmiR319 susceptible to BPH, while suppression of OsmiR319 resistant to BPH in comparison with wild type. Meanwhile, we identified several targets of OsmiR319 that may mediate BPH resistance. Among them, OsPCF5 was the most obviously induced by BPH feeding, and over expression of OsPCF5 was resistance to BPH. In addition, various biochemical assays verified that OsPCF5 interacted with several MYB proteins, such as OsMYB22, OsMYB30, and OsMYB30C.Genetically, we revealed that both OsMYB22 and OsMYB30C positively regulated BPH resistance. Genetic interaction analyses confirmed that OsMYB22 and OsMYB30C both function in the same genetic pathway with OsmiR319b to mediate BPH resistance. Conclusions Altogether, we revealed that OsPCF5 regulates BPH resistance via association with several MYB proteins downstream of OsmiR319, these MYB proteins might function as regulators of BPH resistance through regulating the phenylpropane synthesis.

UDP-N-acetylglucosamine pyrophosphorylase (UAP) is a key enzyme in the chitin biosynthesis pathway of insects. Here, we described the gene SfUAP in the white-backed planthopper Sogatella furcifera (Horváth) with an open reading frame of 1470 bp. Quantitative real-time polymerase chain reaction (qPCR) suggested that SfUAP exhibits a different developmental expression pattern and a higher expression after molting. The highest expression of SfUAP was observed in the integument tissues of adults, whereas head tissues showed negligible expression. RNAi-based gene silencing decreased the mRNA transcript levels in S. furcifera nymphs injected with double-stranded RNA of SfUAP. Finally, SfUAP silencing led to 84% mortality and malformed phenotypes in nymphs. Thus, our results can help better understand the role of SfUAP in S. furcifera.

Some insects have alternative wing morphs, one that is long-winged and changes habitat to follow resources, and one that is short-winged and flightless but has high fertility; here, the molecular details of this switch are revealed, with opposite effects of two insulin receptors controlling the development of different wing morphs in the planthopper. Insect double identity is insulin-linked Some types of insect can exist in two forms, both as long-winged morphs that can move from habitat to habitat to follow resources, and as short-winged flightless morphs with high fertility, but the molecular details of this switch have remained unclear. One species that leads this double life is the migratory brown planthopper Nilaparvata lugens , a serious pest in rice-growing regions of Asia. Chuan-Xi Zhang and colleagues show that long-wing versus short-wing development in N. lugens is controlled through the opposing effects of two insulin receptors, InR1 and InR2, on the activity of the forkhead transcription factor Foxo. Wing polyphenism is an evolutionarily successful feature found in a wide range of insects 1 . Long-winged morphs can fly, which allows them to escape adverse habitats and track changing resources, whereas short-winged morphs are flightless, but usually possess higher fecundity than the winged morphs 1 , 2 , 3 . Studies on aphids, crickets and planthoppers have revealed that alternative wing morphs develop in response to various environmental cues 1 , 2 , 4 , 5 , 6 , 7 , 8 , and that the response to these cues may be mediated by developmental hormones, although research in this area has yielded equivocal and conflicting results about exactly which hormones are involved 4 , 8 , 9 , 10 . As it stands, the molecular mechanism underlying wing morph determination in insects has remained elusive. Here we show that two insulin receptors in the migratory brown planthopper Nilaparvata lugens , InR1 and InR2, have opposing roles in controlling long wing versus short wing development by regulating the activity of the forkhead transcription factor Foxo. InR1, acting via the phosphatidylinositol-3-OH kinase (PI(3)K)–protein kinase B (Akt) signalling cascade, leads to the long-winged morph if active and the short-winged morph if inactive. InR2, by contrast, functions as a negative regulator of the InR1–PI(3)K–Akt pathway: suppression of InR2 results in development of the long-winged morph. The brain-secreted ligand Ilp3 triggers development of long-winged morphs. Our findings provide the first evidence of a molecular basis for the regulation of wing polyphenism in insects, and they are also the first demonstration—to our knowledge—of binary control over alternative developmental outcomes, and thus deepen our understanding of the development and evolution of phenotypic plasticity.

The brown planthopper (BPH) and white-backed planthopper (WBPH) are the most destructive insect pests of rice, and they pose serious threats to rice production throughout Asia. Thus, there are urgent needs to identify resistance-conferring genes and to breed planthopper-resistant rice varieties. Here we report the map-based cloning and functional analysis of Bph6 , a gene that confers resistance to planthoppers in rice. Bph6 encodes a previously uncharacterized protein that localizes to exocysts and interacts with the exocyst subunit OsEXO70E1. Bph6 expression increases exocytosis and participates in cell wall maintenance and reinforcement. A coordinated cytokinin, salicylic acid and jasmonic acid signaling pathway is activated in Bph6 -carrying plants, which display broad resistance to all tested BPH biotypes and to WBPH without sacrificing yield, as these plants were found to maintain a high level of performance in a field that was heavily infested with BPH. Our results suggest that a superior resistance gene that evolved long ago in a region where planthoppers are found year round could be very valuable for controlling agricultural insect pests. The study reports map-based cloning and functional analysis of Bph6 , which is associated with resistance to planthoppers in rice. BPH6 localizes to the exocyst and interacts with OsEXO70E1, and suppression of OsExo70E1 expression decreases resistance in Bph6 -NIL plants.

Pyrops watanabei is a lanternfly species native to Taiwan, and the adults are frequently on Triadica sebifera in summer. Compared to adult longevity, the developmental duration of immature stages from eggs to adult emergence is much longer. Although few records exist, the plants preferred by the immature stages had not been determined prior to this study. Thus, a one-year investigation was conducted to verify the oviposition site preference, determine the plants preferred by nymphs, and examine the change of host ranges with time and development. We establish that Heptapleurum heptaphyllum is not only the preferred egg-laying site, but the main host plant for nymphs from September to the next April, according to our investigations in northern Taiwan. Moreover, the preferred host plant for the nymphs shifts to Triadica sebifera from May onwards to adult emergence. Although Pyrops watanabei is a species native to Taiwan, many fundamental aspects of the species are still poorly documented. Populations of the lanternfly in locations of northern Taiwan were found in abundance and were suitable for the conduction of an investigation from 1 July 2021 to 30 June 2022. We established the shift in the main host plants with different developmental stages. The occurrence of immature individuals on Heptapleurum heptaphyllum increased with age from eggs to nymphs in the third instar; however, it declined from the fourth instar onwards due to a shift in preference to Triadica sebifera. In 2021, the earliest detection of an egg mass was on 1 July. More eggs were recorded in August, and some could be found in September and October of the same year. In 2022, we found an egg mass on 28 June. In August 2021, nymphs in the first and second instars were detected. Then, nymphs in the third and fourth instars appeared after September and October 2021, respectively. Furthermore, nymphs in the fifth instar were sighted as late as March 2022. Finally, this study will provide a basis for further evaluation of the impact of invasion of Pyrops candelaria on the ecology of Pyrops watanabei.

Background The brown planthopper (BPH, Nilaparvata lugens Stål) is a kind of phloem-feeding pest that adversely affects rice yield. Recently, the BPH-resistance gene, BPH6 , was cloned and applied in rice breeding to effectively control BPH. However, the molecular mechanisms underlying BPH6 are poorly understood. Results Here, an integrated miRNA and mRNA expression profiling analysis was performed on BPH6-transgenic (BPH6G) and Nipponbare (wild type, WT) plants after BPH infestation, and a total of 217 differentially expressed miRNAs (DEMs) and 7874 differentially expressed mRNAs (DEGs) were identified. 29 miRNAs, including members of miR160, miR166 and miR169 family were opposite expressed during early or late feeding stages between the two varieties, whilst 9 miRNAs were specifically expressed in BPH6G plants, suggesting involvement of these miRNAs in BPH6-mediated resistance to BPH. In the transcriptome analysis, 949 DEGs were opposite expressed during early or late feeding stages of the two genotypes, which were enriched in metabolic processes, cellular development, cell wall organization, cellular component movement and hormone transport, and certain primary and secondary metabolite synthesis. 24 genes were further selected as candidates for BPH resistance. Integrated analysis of the DEMs and DEGs showed that 34 miRNAs corresponding to 42 target genes were candidate miRNA-mRNA pairs for BPH resistance, 18 pairs were verified by qRT-PCR, and two pairs were confirmed by in vivo analysis. Conclusions For the first time, we reported integrated small RNA and transcriptome sequencing to illustrate resistance mechanisms against BPH in rice. Our results provide a valuable resource to ascertain changes in BPH-induced miRNA and mRNA expression profiles and enable to comprehend plant-insect interactions and find a way for efficient insect control.