PGE₂ mediation of egg development in Western flower thrip, Frankliniella occidentalis

Abstract

Eicosanoids mediate various insect physiological processes, including reproduction. Especially, the eicosanoid prostaglandin E 2 (PGE 2 ) is known to mediate oocyte development in some insects. The explosive reproductive potential of the Western flower thrips, Frankliniella occidentalis, damages various agricultural crops. However, little is known about the underlying physiological processes of egg development in this pest. This study found that treatment with aspirin (ASP) (a specific cyclooxygenase (COX) inhibitor) used to inhibit PGE 2 biosynthesis during ovarian development significantly suppressed the reproduction of female F. occidentalis. However, the addition of PGE 2 to ASPtreated females significantly rescued the suppressed reproduction. PGE 2 was detected in growing ovarian follicles in an immunofluorescence assay. The hypothetical biosynthetic machinery of PGE 2 was predicted from the F. occidentalis genome and included phospholipase A 2 (PLA 2 ), COX-like peroxidase (POX), and PGE 2 synthase (PGES). Three specific PLA 2 s were highly expressed in female adults during active oogenesis. Specific POX and PGES genes also showed high expression during active oogenesis. The adverse effect of ASP treatment on oogenesis was observed in follicle formation in the germarium where the follicle numbers in an ovariole were decreased, which resulted in hypotrophied ovaries. This impairment was rescued by the addition of PGE 2 . ASP treatment also significantly inhibited chorion formation and

Transcriptome analysis of female western flower thrips, Frankliniella occidentalis, exhibiting neo-panoistic ovarian development

“…occidentalis oogenesis. A recent study showed that prostaglandin mediates oocyte devilment in early and late stages in addition to the endocrine signals [ 35 ]. This suggests the oogenesis of F .…”

“…JH acid methyltransferase (JHAMT), JH esterase/ JH epoxide hydrolase, and Met involved in JH synthesis, JH degradation, and the JH receptor, DEGs between transcripts at 0 h and 36 h after adult emergence and 60 h AAE represents DEGs between transcripts at 0 h and 60 h after adult emergence. KEGG categories include alanine, aspartate and glutamate metabolism (1), amino sugar and nucleotide sugar metabolism (2), apoptosis (3), arachidonic acid metabolism (4), ascorbate and aldarate metabolism (5), autophagy (6), biosynthesis of amino acids (7), biosynthesis of cofactors (8), biosynthesis of nucleotide sugars (9), biosynthesis of unsaturated fatty acids (10), carbon metabolism (11), citrate cycle (12), cysteine and methionine metabolism (13), cytochrome P450 ( 14), ECM-receptor interaction (15), endocytosis (16), fatty acid biosynthesis (17), fatty acid elongation (18), fatty acid metabolism (19),folate biosynthesis (20), foxO signaling pathway (21), fructose and mannose metabolism (22), glutathione metabolism (23), glycerolipid metabolism (24), glycerophospholipid metabolism (25), glycine, serine and threonine metabolism (26), glycolysis/gluconeogenesis (27), inositol phosphate metabolism (28), longevity regulating pathway (29), lysine degradation (30), lysosome (31), MAPK signaling pathway (32), metabolic pathways (33), mitophagy (34), glycan biosynthesis (35), nicotinate and nicotinamide metabolism (36), nucleotide metabolism (37), oxidative phosphorylation (38), pentose and glucoronate interconversions (39), pentose phosphate pathway (40), phagosome (41), protein export (42), protein processing in endoplasmic reticulum (43), purine metabolism (44), pyruvate metabolism (45), starch and sucrose metabolism (46), steroid biosynthesis (47), thiamine metabolism (48), Toll and Imd signaling pathway (49), various types of N-glycan biosynthesis (50), vitamin B6 metabolism (51), and Wnt signaling pathway (52).…”

“…Finally, JH, ecdysteroid, and insulin signals may play crucial roles in mediating F. occidentalis oogenesis. A recent study showed that prostaglandin mediates oocyte devilment in early and late stages in addition to the endocrine signals [35]. This suggests the oogenesis of F. occidentalis would be a model system for an integrative analysis of endocrine signals mediating different reproductive processes of previtellogenesis, vitellogenesis, and choriogenesis.…”

A push-pull strategy to control the western flower thrips, Frankliniella occidentalis, using alarm and aggregation pheromones

“…Different reproductive modes along with a short lifecycle allow the thrips population to rapidly increase during early and late seasons, in which female progeny develop from fertilized eggs while males develop from unfertilized eggs [11,12]. The nutrient-based oogenesis of F. occidentalis is well-programmed in females by gonadotropic hormones including juvenile hormone, ecdysone, and prostaglandin [13,14]. To suppress thrips outbreaks, more than 20 kinds of chemical insecticides including organophosphate, carbamate, pyrethroids, neonicotinoids, avermectin, and spinosad are registered and applied to different agricultural crops [15].…”