ABSTRACT
Diorhabda rybakowi Weise is one of the dominant pests feeding on Nitraria spp., a pioneer plant used for windbreaking and sand fixation purposes, and poses a threat to local livestock and ecosystems. To clarify the key olfactory genes of D. rybakowi and provide a theoretical basis for attractant and repellent development, the optimal reference genes under two different conditions (tissue and sex) were identified, and the bioinformatics and characterization of the tissue expression profiles of two categories of soluble olfactory proteins (OBPs and CSPs) were investigated. The results showed that the best reference genes were RPL13a and RPS18 for comparison among tissues, and RPL19 and RPS18 for comparison between sexes. Strong expressions of DrybOBP3, DrybOBP6, DrybOBP7, DrybOBP10, DrybOBP11, DrybCSP2, and DrybCSP5 were found in antennae, the most important olfactory organ for D. rybakowi. These findings not only provide a basis for further in-depth research on the olfactory molecular mechanisms of host-specialized pests but also provide a theoretical basis for the future development of new chemical attractants or repellents using volatiles to control D. rybakowi.
ABSTRACT
BACKGROUND: Brood pollination mutualism is a special type of plant-pollinator interaction in which adult insects pollinate plants, and the plants provide breeding sites for the insects as a reward. To manifest such a mutualism between Stellera chamaejasme and flower thrips of Frankliniella intonsa, the study tested the mutualistic association of the thrips life cycle with the plant flowering phenology and determined the pollination effectiveness of adult thrips and their relative contribution to the host's fitness by experimental pollinator manipulation. RESULTS: The adult thrips of F. intonsa, along with some long-tongue Lepidoptera, could serve as efficient pollinators of the host S. chamaejasme. The thrips preferentially foraged half-flowering inflorescences of the plants and oviposited in floral tubes. The floral longevity was 11.8 ± 0.55 (mean ± se) days, which might precisely accommodate the thrips life cycle from spawning to prepupation. The exclusion of adult thrips from foraging flowers led to a significant decrease in the fitness (i.e., seed set) of host plants, with a corresponding reduction in thrips fecundity (i.e., larva no.) in the flowers. CONCLUSIONS: The thrips of F. intonsa and the host S. chamaejasme mutualistically interact to contribute to each other's fitness such that the thrips pollinate host plants and, as a reward, the plants provide the insects with brooding sites and food, indicating the coevolution of the thrips life cycle and the reproductive traits (e.g., floral longevity and morphology) of S. chamaejasme.
Subject(s)
Flowers/physiology , Pollination/physiology , Thymelaeaceae/physiology , Thysanoptera/physiology , Animals , Larva , SymbiosisABSTRACT
In order to investigate the changes of secondary metabolites content of alfalfa induced by thrips Odontothrips loti damaging, two alfalfa strains, one resistant to thrips (R-1) and the other susceptible to thrips (I-1) , were chosen to measure the phenols and lignin contents of alfalfa leaves under infestation with thrips at different densities (0, 1, 3, 5, 7 thrips x branch(-1), and 0 thrip x branch(-1) as control). After infestation 7 days, the polyphenols, tannin and condensed tannin contents increased in both leaves of R-l and I-i with the increasing thrips density, the simple phenols content had no significant difference, while the lignin content increased significantly compared with the control. After infestation 14 days, the polyphenols, tannin, condensed tannin and lignin contents in both leaves of R-1 and I-1 increased obviously with the increasing thrips density, while the simple phenols content had no significant difference. The lignin content increased significantly, and was significantly higher under 7 thrips x branch(-1) than under the control. After infestation 21 days, the polyphenols, tannin, and lignin contents in both leaves of R-1 and I-1 increased obviously with the increasing thrips density, and were the highest under 7 thrips x branch(-1). Simple phenols content of I-1 strain was increased significantly, but that of R-1 strain had no significant change. The condensed tannin content in both leaves of R-1 and I-1 was not obvious compared with the control. Phenols and lignin contents in R-1 and I-1 leaves increased obviously after thrips infestation, and the polyphenols, tannin and lignin contents increased faster in R-1 strain than in I-1 strain. Thrips infestation had inductive effects on phenols and lignin contents of alfalfa, which could be used to evaluate the resistance of alfalfa.
