Physiological Entomology最新文献

Fatty acyl-CoA reductases (FARs) play an important role in the synthesis of fatty alcohols in various organisms. Based on the important function of FAR genes, they can be used as a potential molecular target for controlling agricultural pests. Although the FAR genes have been studied in a number of insects, the gain, loss, and molecular evolution of FAR genes between different Hemipteran species still require comprehensive and systematic study. This study systematically identified and analysed 352 FAR genes from 12 Hemipteran species, including six typical true bug species, Cimex lectularius, Apolygus lucorum, Halyomorpha halys, Oncopeltus fasciatus, Rhodnius prolixus and Gerris buenoi. The number of FAR genes per species ranged from 17 to 43, and a phylogenetic analysis showed that the identified FAR genes of Hemiptera can be classified into 11 clades. The gain and loss of FAR genes have occurred in some Hemipteran species. These FAR genes conform to the birth-and-death model in the evolutionary process. Through selection pressure analysis, we determined that G. buenoi in clade 11 evolved under the pressure of positive selection, with the evolutionary sites of A at position 214 and T at position 451, thus clarifying the differences in amino acids among species and providing a better understanding of the molecular evolutionary mechanism of Hemipteran FAR. In addition, structural analysis of the FAR genes revealed duplication of the two conservative domains, the Rossmann-fold domain and the sterile domain, of the FAR in four species, namely Bemisia tabaci, Diaphorina citri, R. prolixus and Trialeurodes vaporariorum. This study lays a foundation for further studies on the molecular functions of Hemiptera FAR, and provides a possible new target for the control of Hemiptera, especially the stink bugs.

Previously we proposed one aspect of how insects could adapt to terrestrial environments during their evolution. The hypothesis is based on a theory that insects have evolved an insect-specific system for cuticle formation mediated by an insect-specific enzyme. This enzyme, multicopper oxidase-2 (MCO2), catalyses the oxidation of catecholamines using molecular oxygen as the acceptor of electrons from the substrates. A potential advantage of this MCO2-mediated system is the utilization of molecular oxygen abundant in the atmosphere, which is different from the case in crustaceans (close relatives of insects) that utilize calcium ions. Accumulation of calcium ions leads to an increase in weight, but the lightweight cuticle without calcification might have been a critical factor enabling insects to evolve flight first in the history of Metazoa. Our theory also provides a simple explanation to a long-standing question of why insects are so rare in marine environments. In previous reviews, we have mainly focused on the details of the biochemical processes occurring in arthropod cuticles, but here only the essence of our theory is extracted and briefly summarized with newly added information.

We analysed whether the source of zinc (inorganic and organic) influences the morphology of the hypopharyngeal gland (HPG) and the relative expression of major royal jelly protein (MRJP) genes in nursing bees at 6 days of age. For this, 15 colonies of Apis mellifera bees were subjected to the following treatments: Zn0 (control), zinc methionine (50 ppm) and zinc sulphate monohydrate (50 ppm) during the off-season (characterized by food reduction). MRJP1 and MRJP5 gene expression was analysed using real-time PCR and HPG sections under a microscope. Bee mortality and population development were also evaluated for 30 days. It was observed that the honeybees consumed all sugar syrup containing zinc both in its organic and inorganic forms, which did not promote mortality or affect population development. Regarding HPG morphometry, it was observed that zinc, regardless of the source, promoted the acini area significantly greater than that of the control. Zn methionine promoted a significant increase in HPG area compared with that of an inorganic source. The relative expression of MRJP1 and MRJP5 was not significantly affected compared with the control. We conclude that the mineral Zn promotes an increase in the HPG area and does not alter the pattern of expression of the MRJP1 and MRJP5 genes, and that the organic source of the mineral presents the best results.

Insect larvae typically moult to grow, but here we investigate insect larvae that moult to shrink; that is, retrogressive moulting or retrogressive development. We demonstrate this phenomenon in khapra beetle, Trogoderma granarium Everts (Dermestidae), among the world's most invasive pests of stored grains and cereal products, and a quarantine pest of interest for many countries. Larvae survived a 3-month period of starvation, moulting up to six times and reducing their body mass by about half, on average. When reprovisioned with food, most larvae resumed the normal trajectory of development and pupated within a month. Thus, retrogressive development is a mechanism that may favour species whose resources exhibit feast-or-famine dynamics. By enabling survival during periods of privation, retrogressive development contributes to the invasiveness of the khapra beetle by allowing them to persist for long periods in empty storage facilities or empty containers used for international grain shipments.

Recent studies have reported wing interference patterns (WIPs), which reflect the microstructure of the wing, for small insects belonging to the Diptera and Hymenoptera orders. WIPs have been evaluated using RGB or multispectral images, but in contrast to these approaches, hyperspectral images allow a more detailed analysis of spectral variation, which may not be captured by RGB or multispectral images. Here, I investigated the WIPs of 12 Drosophila species using hyperspectral images. The average spectrum was calculated for each of the six compartments of the wing region and for the entire wing, including all six compartments. This information was used to evaluate sexual and interspecific differences in the WIPs of 12 Drosophila species. In addition, the possibility of species discrimination based on WIPs was explored using the random forest machine learning algorithm. The present study demonstrates significant sex and interspecific differences in WIPs for each of the six compartments of the wing regions as well as for the entire wing region. The results of the random forest machine learning algorithm suggested the possibility of species identification based on WIPs.

Organisms trade-off limited resources between life-history traits to maximize fitness. In particular, costs associated with reproduction are balanced against somatic maintenance and this can result in age-dependent changes in the optimal allocation of resource to reproduction. Changes in the allocation of resources to reproduction with age were considered in the facultatively parasitic blowfly Lucilia sericata (Diptera: Calliphoridae), using biochemical analysis of lipids in the body and ovary, and lipid and protein in individual eggs. Resource allocation to reproduction, measured as lipid content in the ovary, declined over time. This decline was associated with the production of fewer and smaller eggs per batch. The lipid content of the residual body did not change. A decrease in lipid and increase in protein contents of individual eggs over time, although statistically significant, were relatively slight, suggesting that age-related changes in nutritional allocation to individual eggs were more subtle than changes in egg batch number or size. This study highlights the insights to be gained from considering both biochemical measures of nutritional allocation, and observable measures of reproductive effort, when evaluating how females balance allocation across competing life-history traits. Future work should explore how allocation patterns might vary under conditions of resource constraint and whether age-dependent allocation in laboratory flies is representative of that found in wild populations.

The midgut of bees plays a significant role in digestion and absorption and is a gateway for pathogens. As a protection for the organism, the midgut lumen is lined by a peritrophic matrix rich in chitin fibrils, associated with proteins that form multiple resistant layers with gelatinous consistency, with several functions, including the mechanical barrier against infection by pathogens. The obligate intracellular microsporid Nosema ceranae is an important pathogen that decreases honey production, increases pesticide susceptibility, and may cause mortality in the honey bee Apis mellifera. This study evaluated whether the peritrophic matrix has a protective function against infection by N. ceranae in A. mellifera adult workers. The peritrophic matrix integrity was changed by feeding the bees with calcofluor white (CFW), followed by an artificial infection with N. ceranae spores. Results shown that 0.5% CFW affect the integrity of the peritrophic matrix with areas of interruption of this envelope. This disorganization of the peritrophic matrix reduces the life cycle period of N. ceranae from eight to four days, after inoculation, and increases the concentration of new spores released in the midgut lumen. This is the first report on the importance of the peritrophic matrix as a protective barrier against N. ceranae infection in A. mellifera.

The wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae), is a major pest of wheat grown on the Northern Great Plains and Canadian Prairies of North America, causing economic losses of as much as $350 million annually. Two species that parasitize wheat stem sawfly larvae in wheat stems are Bracon cephi (Gahan) and B. lissogaster Muesebeck (Hymenoptera: Braconidae). Carbohydrate-rich diets increase adult parasitoid longevity and reproductive parameters, enhancing their success as natural enemies. In previous studies, these species had increased longevity, egg load, and volume when fed sucrose solutions, encouraging further research on their nutritional needs. Therefore, we conducted experiments with artificial diets using adult females fed sucrose, glucose, and fructose solutions. Females were also fed these sugars in combination with a mixture of amino acids. We assessed individuals daily for longevity. Both species benefited from diets containing carbohydrates, with an increase in longevity from an average of 9 to 51 days for B. cephi, and from 6 to 34 days for B. lissogaster. Additional experiments assessed egg load and volume after 2, 5, and 10 days of cumulative feeding in B. cephi. These females produced 1.4-fold more eggs when fed amino acids, 2.5-fold more with sugar, and 2.7-fold more when fed sugar with amino acids. They had a 1.3-fold increase in egg volume when fed amino acids, 1.9-fold with sugar, and 2.1-fold when fed sugar with amino acids. Our study reveals the nutritional requirements of these braconid parasitoids and the benefits of nutritional sources when implementing conservation biological control strategies.