the pest species Spodoptera frugiperda, which is native to north and South America, has invaded Africa in 2016. The species consists of two strains, the corn-strain and rice-strain, which differ in their sexual communication. When we investigated populations from Benin and nigeria, consisting of corn-strain and rice-corn-hybrid descendants, we found no strain-specific sexual communication differences. Both genotypes exhibited the same pheromone composition, consisting of around 97% (Z)-9-tetradecenyl acetate (Z9-14:Ac), 2% (Z)-7-dodecenyl acetate (Z7-12:Ac), and 1% (Z)-9-dodecenyl acetate (Z9-12:Ac), they had similar electrophysiological responses, and all mated around three hours into scotophase. However, we found geographic variation between African and American populations. The sex pheromone of African corn-strain and hybrid descendant females was similar to American ricestrain females and showed higher percentages of the male-attracting minor component Z7-12:Ac. In addition, African males exhibited the highest antennal sensitivity towards Z7-12:Ac, while American males showed highest sensitivity towards the major pheromone component Z9-14:Ac. Increasing the production of and response to the critical minor component Z7-12:Ac may reduce communication interference with other African Spodoptera species that share the same major pheromone component. The implications of our results on pheromone-based pest management strategies are discussed.Since 2016 the African continent has a new pest species: the fall armyworm (FAW) Spodoptera frugiperda (Lepidoptera: Noctuidae) 1 . This noctuid moth species is endemic to North and South America and is known as serious pest of maize, sorghum, sugarcane, and various grasses 2,3 . Although FAW is a generalist feeding on over 350 different host plants in the Americas 4 , its major host in Africa is maize 5 , also endemic to the Americas. The rapid spread of FAW to almost all sub-Saharan countries within less than two years 5 , and the magnitude of agricultural losses (estimated over US$ 13.3 billion 6 ), highlight the need for efficient pest management strategies in Africa. As FAW encounters new ecological conditions, ecosystem dynamics, and species interactions in Africa, this invasive species may behave differently in its new environment, and pest control methods that work in the Americas might not be effective in Africa. Therefore, it is crucial to first understand the biology of FAW in its new habitat in order to develop control methods that are effective and affordable for regional farmers.One commonly used and environmentally friendly method to monitor or control pest insects is the use of sex pheromones, which are crucial for the mate finding process in moths 7 . In most noctuid species like FAW, the females emit a species-specific sex pheromone in the scotophase to attract males over large distances, which is the start of the mating phase 8 . In its native environment in North and South America, several sex pheromone based pest management strategies have been used to regul...

BACKGROUND: The fall armyworm, Spodoptera frugiperda is a native species of the Americas. First detected in western and central Africa in early 2016, it has become one of the most serious invasive lepidopteran pests in many African and Asian countries. S. frugiperda has spread very quickly; however, there are no molecular-based, simple and accurate diagnostic tools for identification of this species in the field. Methods to identify invasive S. frugiperda are urgently needed because farmers and agricultural managers have no prior experience with this pest. RESULTS: Based on mitochondrial genome sequence alignment, a S. frugiperda-specific sequence region was identified in the transfer RNA-coding region between NADH dehydrogenase, ND3, and ND5. Using this unique region, species-diagnostic primers were designed and applied in a loop-mediated isothermal amplification (LAMP) assay and a conventional polymerase chain reaction to identify field-collected samples of S. frugiperda. The optimal incubation conditions for the LAMP assay were 61°C for 90 min with four LAMP primers; an additional loop primer increased the amplification efficiency. A response was obtained for a wide range of DNA concentrations in the LAMP assay and the minimum detectable DNA concentration was 10 pg.CONCLUSIONS: We developed a new LAMP-based molecular diagnostic method that it is easy to use and accurate. The LAMP assay was used with a DNA-releasing technique for larval and adult samples, without a DNA extraction step, by incubating the tissue sample at 95°C for 5 min. This method can be applied in intensive field monitoring of S. frugiperda and its ecological studies.

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The fall armyworm, Spodoptera frugiperda is a native species in the Americas. However, nowadays it is one of the most serious invasive lepidopteran pests in African and Asian countries. S. frugiperda has been spread very quickly after the first outbreak was reported in many countries. Based on mt genome sequence alignment, S. frugiperda specific sequence region was identified in tRNAs coding region between NADH dehydrogenase, ND3 and ND5.By using this unique region, species diagnostic primers were designed and applied in LAMP (lamp loop mediated isothermal amplification) assay as well as conventional PCR to identify the field-collected samples of S. frugiperda. Optimal incubation condition of LAMP assay was 61℃ for 90 minutes with 4 LAMP primers, and additional loop primer increased the amplification efficiency. Also, wide range of DNA concentration responded in LAMP assay and minimum detectable DNA concentration was 10 pg. This LAMP assay was also applied in DNA releasing technique from larval and adult sample, without DNA extraction, 95℃ incubation for five minutes of the tissue sample. This new molecular diagnostic method is easy to use and accurate. It possibly applied in intensive field monitoring of S. frugiperda and its ecological studies.

Many herbivorous insects selectively accumulate plant toxins for defense against predators; however, little is known about the transport processes that enable insects to absorb and store defense compounds in the body. Here, we investigate how a specialist herbivore, the horseradish flea beetle, accumulates high amounts of glucosinolate defense compounds in the hemolymph. Using phylogenetic analyses of coleopteran membrane transporters of the major facilitator superfamily, we identified a clade of glucosinolate-specific transporters (PaGTRs) belonging to the sugar porter family. PaGTR expression was predominantly detected in the excretory system, the Malpighian tubules. Silencing of PaGTRs led to elevated glucosinolate excretion, significantly reducing the levels of sequestered glucosinolates in beetles. This suggests that PaGTRs reabsorb glucosinolates from the Malpighian tubule lumen to prevent their loss by excretion. Ramsay assays performed with dissected Malpighian tubules confirmed a selective retention of glucosinolates. Thus, the selective accumulation of plant defense compounds in herbivorous insects can depend on the ability to prevent excretion.