Monoterpenoid signals and their transcriptional responses to feeding and juvenile hormone regulations in bark beetle Ips hauseri Reitter

Hauser's engraver beetle Ips hauseri Reitter is a serious pest in spruce forest ecosystems in Central Asia. Its monoterpenoid signal production, transcriptome responses, and potential regulatory mechanisms remain poorly understood. The quality and quantity of volatile metabolites in hindgut extracts of I. hauseri were found to differ between males and females and among three groups: beetles that are newly emerged, those with a topical application of juvenile hormone III (JHIII), and those that have been feeding for 24 h. Feeding males definitively dominate monoterpenoid signal production in I. hauseri, which uses (4S)-(–)-ipsenol and (S)-(–)-cis-verbenol to implement reproductive segregation from I. typographus and I. shangrila. Feeding stimulation can induce higher expression of most genes related to the biosynthesis of (4S)-(–)-ipsenol than JHIII induction, and it shows a male-specific mode in I. hauseri. JHIII can stimulate males to produce large amounts of (–)-verbenone and also upregulates a higher expression of several CYP6 genes in males than females. The expression of genes involved in the metabolism of JHIII in females and males were found to be upregulated. A species-specific aggregation pheromone system for I. hauseri, consisting of (4S)-(–)-ipsenol and S-(–)-cis-verbenol, can be used to monitor population dynamics or mass trap killing. Our results also enable a better understanding of the bottom-up role of feeding behaviors in mediating population reproduction/aggregation and interspecific interactions.

The Attractive Effects of Amino Acid and Some Classical Substances on Grass Carp (Ctenopharyngodon Idellus)

Grass carp (Ctenopharyngodon idellus) is one of the most essential fishing species in China. The bait for this fish is rapidly developing. However, the study on the attractants in the bait for this fish lacks. This study was designed to systematically investigate the effects of 16 kinds of stimuli on the perspective of behaviour and physiology of grass carp by using different kinds of methods, including behavioral tests (maze test and biting-balls test) and electro-olfactogram (EOG). Our experiment's idea is mainly to imitate: in addition to vision, fish in nature also use smell to find food and finally swallow under the action of olfaction, taste and other sensory systems. Firstly, the behavioral maze test was used to screen the attractive or suppressive effect of 16 stimuli on grass carp and the electronic olfactory recording method was used to further evaluate the olfactory response of grass carp to the eight stimuli selected from the maze test. Then, the best concentrations of these eight stimuli and their combination were investigated by the biting-balls test to compound a formula with the strongest appetite for grass carp. The results of behavioral maze test showed that DMPT, DMT, glycine, Taurine, L-glutamic, L-alanine, L-proline, L-arginine have different degrees of useful in attracting grass carp. The electro-olfactogram recoding showed that the EOG response of grass carp to the stimuli is a transient biphasic potential change and all of the eight stimuli could induce the EOG response of grass carp. The biting-balls test showed that glycine, L-glutamic, L-arginine at 10–2 mol/L had significant feeding stimulation and DMT at 10–1 mol/L had significant feeding stimulation than the other groups. Finally, formula 9 composed of DMT, glycine, L-glutamic acid and L-arginine has the greatest attraction for grass carp. The results of this study verified the attractive effect of some amino acids and other chemicals on grass carp fishing, and would provide support for the production of specific grass carp attractants.

Feed efficiency, nutrient sensing and feeding stimulation in aquaculture: A review

Ameliorating of feed efficiency always was and will remain the key element of aquaculture in which minimalizing losses during feed intake play an important role. Decreasing feed losses important not only from the economic point of view but also from an environmental standpoint. Feeding stimulants are often used additives in complete aquaculture feeds. Better knowledge of the food-sensing of cultured species is essential in the development of adequate feeding stimulants. The present paper aims to overview the nutrient-sensing of aquatic animals and the use of the wide variety of feeding attractants and stimulants.

Effect of Resistant and Susceptible East European Pears on Development and Mortality of the Pear Psylla, Cacopsylla pyricola (Förster)

Pear psyllids (Cacopsylla spp., Hemiptera: Psyllidae) are major pests of European pear (Pyrus communis L.) in North America and Europe. In breeding resistant cultivars, a thorough understanding of the nature of host resistance and susceptibility is essential for designing efficient and accurate methods to identify resistant host genotypes. A developmental assay was performed on six genotypes previously identified as highly resistant, moderately resistant, or susceptible to nymphal feeding. Plants were infested with first instars of Cacopsylla pyricola (Förster), and feeding, mortality, and larval stage were observed for 34 days. Host genotypes significantly differed in feeding antixenosis at day 1 after infestation. Differences in antibiosis were also evident, as mortality of nymphs was greater on the feeding-resistant genotypes. There were also differences in the total numbers of surviving psylla and those developing to adults. Survival was directly related to the feeding antixenosis. There were no significant differences among the feeding-susceptible and moderately resistant genotypes in population age structure, except at day 19, reflecting the advanced stage of the few nymphs that did survive. Early feeding antixenosis was associated with mortality, either through a lack of feeding stimulation, feeding inhibition, or because of a direct toxic effect of the resistant plant genotypes. The short-term feeding antixenosis assay is predictive of long-term mortality and, to a lesser extent, with delayed development. ‘Bartlett’ and the wild seedling Y-167 were confirmed as susceptible, ‘Karamanlika’ and NY10352 were confirmed as moderately resistant, and Bacui-1 and Bacui-2 were confirmed as highly resistant.