Hong-Lei Wang

Sex pheromones are eco‐friendly agents to control pest insects. Yet, the cost of synthetic pheromone production has restricted their use essentially to high value crops. Plant‐based bioproduction of pheromone compounds offers a promising and sustainable alternative, opening up for the deployment of pheromone‐mediated pest control also in row crops. The rice leaffolder Cnaphalocrocis medinalis uses C18 pheromone compounds and is a major rice pest in South China. We demonstrate that the fatty acid precursor of the main C18 pheromone component of Cnaphalocrocis medinalis , ( Z )‐13‐octadecenal, can be biotechnologically produced using the oilseed crop Camelina sativa . First, we used deuterium‐labelling to establish an elongation‐based pathway for pheromone precursor formation from hexadecanoic (palmitic) acid via desaturation to ( Z )‐11‐hexadecenoic acid and elongation to ( Z )‐13‐octadecenoic acid. Using transient expression in Nicotiana benthamiana , we identified a minimal pathway consisting of a ∆11 desaturase ( CmedDES1 ), an elongase ( CmedELO1 ), and a fatty acyl reductase ( CmedFAR2 ) for the heterologous biosynthesis of long‐chain monounsaturated C18 precursors in planta . Co‐expression of the insect desaturases CmedDES1 or CsupYPAQ with the Camelina elongase CsaKCS1 in Nicotiana benthamiana resulted in higher production of Z13‐18 products compared to co‐expression with insect elongases. We finally engineered Camelina sativa seeds through seed‐specific co‐expression of the Z11‐16‐forming insect desaturase CsupYPAQ and CsaKCS1 elongase, enabling the accumulation of C18 fatty acid pheromone precursors. Our study paves the way for sustainable production of the sex pheromone of Cnaphalocrocis medinalis and other C18 monounsaturated pheromone precursors for crop protection.

Sex pheromones are eco-friendly agents to control pest insects. Yet, the cost of synthetic pheromone production has restricted their use essentially to high value crops. Plant-based bioproduction of pheromone compounds offers a promising and sustainable alternative, opening up for the deployment of pheromone-mediated pest control also in row crops. The rice leaffolder Cnaphalocrocis medinalis uses C18 pheromone compounds and is a major rice pest in South China. We demonstrate that the fatty acid precursor of the main C18 pheromone component of C. medinalis , ( Z )-13-octadecenal, can be biotechnologically produced using the oilseed crop Camelina sativa . First, we used deuterium-labelling to establish an elongation-based pathway for pheromone precursor formation from hexadecanoic (palmitic) acid via desaturation to ( Z )-11-hexadecenoic acid and elongation to ( Z )-13-octadecenoic acid. Using transient expression in Nicotiana benthamiana , we identified a minimal pathway consisting of a Δ11 desaturase ( CmedDES1 ), an elongase ( CmedELO1 ), and a fatty acyl reductase ( CmedFAR2 ) for the heterologous biosynthesis of long-chain pheromone monounsaturated C18 precursors in planta. Co-expression of the insect desaturases CmedDES1 or CsupYPAQ with the Camelina elongase CsaKCS1 in Nicotiana benthamiana resulted in higher production of Z13-18 products compared to co-expression with insect elongases. We finally engineered Camelina sativa seeds through seed-specific co-expression of the Z11-16-forming insect desaturase CsupYPAQ and CsaKCS1 elongase, enabling the accumulation of C18 fatty acid pheromone precursors. Our study paves the way for sustainable production of the sex pheromone of C. medinalis and other C18 monounsaturated pheromone precursors for crop protection.

Bird embryos develop inside eggs, which contain maternal substances that can shape offspring phenotype and fitness. Yolk fatty acids are a key energy source for the developing embryo, with omega‐6 (ω‐6) and omega‐3 (ω‐3) polyunsaturated fatty acids (PUFAs) obtained exclusively from the diet. Therefore, food availability during the breeding season is expected to influence yolk fatty acid composition and, consequently, embryo development and growth. However, the effects of dietary variation on yolk fatty acids remain unexplored in wild birds. We investigated interannual variation in yolk fatty acid composition of free‐living great tits Parus major in relation to fluctuations in beech Fagus sylvatica fructification – their preferred food – across two years differing strongly in seed abundance. We hypothesized that differences in beech seed availability would alter yolk fatty acid composition between years of high and low fructification, with corresponding correlations to the fatty acid profiles of available seeds. Hence, we analyzed fatty acids from seeds of beech and two conifers ( Picea abies and Pinus sylvestris ), which account for most of the tree cover in the study area, and from 112 eggs collected from 107 nests over two years. Beech seeds contained higher proportions of saturated (SFA), monounsaturated (MUFA), and ω‐3 PUFAs, and lower proportions of ω‐6 PUFAs than conifer seeds. Correspondingly, egg yolks had more SFA, MUFA, and ω‐3 PUFAs in the year of high beech abundance, and more ω‐6 PUFAs in the year of low abundance. Notably, the proportion of the conifer‐associated ω‐6 PUFA pinolenic acid was 64.25 times higher in years of low compared to high beech fructification, suggesting marked interannual variation in yolk fatty acid composition, likely reflecting shifts in maternal diet. Future experiments need to establish causal links between diet and yolk composition and assess the fitness consequences of different seed resources for breeding females and their offspring.

Bark beetle species of the genera Ips and Dendroctonus represent a threat to forests in both North America and Europe. Under normal circumstances, these beetles recycle dying trees into nutrients, but under certain conditions, growing populations can overcome healthy tree defenses and cause severe economic loss in forestry. The most economically relevant bark beetle species communicate with aggregation pheromones such as ipsdienol, cis ‐verbenol and trans‐ verbenol. These pheromones are currently used in synthetic baits as part of control strategies for bark beetles, although their chemical synthesis makes them expensive to use. Here, we explore the possibility of producing bark beetle pheromones in plant factories, since these compounds can be derived from isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP) from the mevalonic acid (MVA) and methylerythritol phosphate (MEP) pathways in plants. By the combined expression of enzymes from plants and bark beetles, we show that Arabidopsis thaliana can produce the intermediates β‐myrcene (ipsdienol biosynthesis pathway) and α‐pinene (verbenol biosynthesis pathway). Furthermore, we were able to produce the final products cis‐ verbenol and trans‐ verbenol in stably transformed Arabidopsis, without the addition of external substrates. Finally, we achieved the production of verbenone, an anti‐aggregation pheromone derived from verbenol, which deters bark beetles from a host. These results are an important step towards using plants as biofactories for a cheaper and greener production of pheromones and repellent components for artificial baits.

Bird embryos develop inside eggs, which contain maternal substances that can shape offspring phenotype and fitness. Yolk fatty acids are a key energy source for the developing embryo, with omega-6 (ω-6) and omega-3 (ω-3) polyunsaturated fatty acids (PUFAs) obtained exclusively from the diet. Therefore, food availability during the breeding season is expected to influence yolk fatty acid composition and, consequently, embryo development and growth. However, the effects of dietary variation on yolk fatty acids remain unexplored in wild birds. We investigated inter-annual variation in yolk fatty acid composition of free-living great tits ( Parus major ) in relation to fluctuations in beech ( Fagus sylvatica ) fructification—their preferred food—across two years differing strongly in seed abundance. We hypothesized that differences in beech seed availability would alter yolk fatty acid composition between years of high and low fructification, with corresponding correlations to the fatty acid profiles of available seeds. Hence, we analyzed fatty acids from seeds of beech and two conifers ( Picea abies and Pinus sylvestris ), which account for most of the tree cover in the study area, and from 112 eggs collected from 107 nests over two years. Beech seeds contained higher proportions of saturated (SFA), monounsaturated (MUFA), and ω-3 PUFAs, and lower proportions of ω-6 PUFAs than conifer seeds. Correspondingly, egg yolks had more SFA, MUFA, and ω-3 PUFAs in the year of high beech abundance, and more ω-6 PUFAs in the year of low abundance. Notably, the proportion of the conifer-associated ω-6 PUFA pinolenic acid was 64.25 times higher in years of low compared to high beech fructification, suggesting marked inter-annual variation in yolk fatty acid composition, likely reflecting shifts in maternal diet. Future experiments need to establish causal links between diet and yolk composition and assess the fitness consequences of different seed resources for breeding females and their offspring.

The sense of smell is a central sensory modality of most terrestrial species. However, our knowledge of olfaction is based on vertebrates and insects. In contrast, little is known about the chemosensory world of spiders and nothing about how they perform olfaction despite their important ecological role. The orb-weaving spider Argiope bruennichi lends itself to an in-depth study on olfaction as it is one of the few spider species whose volatile sex pheromone, emitted by females to attract males, is known. We combined ultrastructural and electrophysiological analyses and found that previously overlooked sensilla with wall pores are abundant on all walking legs of A. bruennichi males. We compared the ultrastructure of these wall-pore sensilla with those known to perform olfaction in insects, exploring similarities and differences. Electrophysiological single sensillum recordings demonstrated that the wall-pore sensilla in A. bruennichi respond highly sensitive and in a concentration-dependent manner to the sex pheromone. Our study demonstrates male-specific sensilla for detecting signaling females, whereas females and subadult males are devoid of wall pore sensilla. In a preliminary comparative morphological analysis using 19 species from 16 spider families, we found that wall-pore sensilla occur in male spiders from most, but not in basally branching clades or in Salticids, suggesting that wall-pore sensilla evolved at least once within spiders and were lost at least once. This research significantly expands our knowledge of the sensory ecology of spiders, will stimulate studies on the diversity and function of sensilla, as well as studies on the evolution of olfaction in arthropods.

Aphids cause massive agricultural losses through direct damage or as pathogen vectors. Control often relies on insecticides, which are expensive and not selective. An interesting alternative is to use aphid sex pheromones nepetalactone (NON) and nepetalactol (NOL) to interfere with aphid mating or attract aphid predators. Here, we explore production of these compounds in plants, as their precursors can be derived from mevalonate (MVA) and methylerythritol phosphate (MEP) pathways. By introducing six genes, including a major latex protein‐like (MLPL) enzyme, we engineered a functional nepetalactol biosynthetic pathway into plants. Transient expression of these enzymes in N. benthamiana caused production of nepetalactone, without the need for external supplementation with substrates. Targeting all six enzymes into the chloroplast appeared to result in higher NON yields than just chloroplast‐targeting the first two enzymes. We could not detect NOL, suggesting it is rapidly oxidised to NON. In addition, we produced NON in stably transformed Camelina sativa (Camelina) lines. Interestingly, the specific NON enantiomer was different in N. benthamiana compared to in Camelina, indicating the value of different platforms for producing specific isoforms. This opens possibilities for using plants as green factories of pheromones for baits or as pheromone dispensers that interfere with insect behaviour.

BACKGROUND: The sugarcane borer Diatraea saccharalis (Lepidoptera) is a key pest on sugarcane and other grasses in the Americas. Biological control as well as insecticide treatments are used for pest management, but economic losses are still significant. The use of female sex pheromones for mating disruption or mass trapping in pest management could be established for this species, provided that economical production of pheromone is available.RESULTS: Combining in vivo labelling studies, differential expression analysis of transcriptome data and functional characterisation of insect genes in a yeast expression system, we reveal the biosynthetic pathway and identify the desaturase and reductase enzymes involved in the biosynthesis of the main pheromone component (9Z,11E)‐hexadecadienal, and minor components hexadecanal, (9Z)‐hexadecenal and (11Z)‐hexadecenal. We next demonstrate heterologous production of the corresponding alcohols of the pheromone components, by expressing multiple steps of the biosynthetic pathway in yeast.CONCLUSION: Elucidation of the genetic basis of sex pheromone biosynthesis in D. saccharalis, and heterologous expression in yeast, paves the way for biotechnological production of the pheromone compounds needed for pheromone‐based pest management of this species. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Pheromones have become an environmentally friendly alternative to conventional insecticides for pest control. Most current pheromone-based pest control products target lepidopteran pests of high-value crops, as today’s manufacturing processes cannot yet produce pheromones at low enough costs to enable their use for lower-value crops, especially commodity crops.Camelina sativaseeds genetically modified to express (Z)-11-hexadecenoic acid, a sex pheromone precursor of several moth species, provided the oil from which the precursor was isolated, purified and transformed into the final pheromone. Trap lures containing this pheromone were then assessed for their capacity to manage moth pests in the field. Plant-derived pheromone lures proved equally effective as synthetic pheromone lures in monitoring the diamondback moth,Plutella xylostella, in cabbage and disrupting mating of cotton bollworm,Helicoverpa armigera, in common bean fields. Our study demonstrates the biological efficacy and economic feasibility of pheromone production in plant factories by metabolic engineering of an oilseed crop.