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Simple Summary: This article studies the interaction between two parasites, a parasitoid (Sclerodermus guani) and an entomopathogenic fungus (Beauveria bassiana) on the same host, a longicorn beetle Monochamus alternatus. We focused on the survival and reproduction of the parasitoid's parent and its offspring fitness under different concentrations of B. bassiana suspension in the laboratory. The results show that S. guani parent females carrying higher concentrations of the pathogen shorten the pre-reproductive time and regulate their own fertility and their offspring's survival and development. Under the stress of the entomopathogenic fungus B. bassiana, the mortality effect of the parasitoid S. guani to its host M. alternatus was also assessed by the interspecific relationship model, which contained three dimensionless parameters: the ratio vulnerability, dilution ratio, and PR (the ratio of the total number of parasitoids successfully controlling host larvae M. alternatus to the total number of parasite events during parasitism). These findings shed light on the potential interspecific interactions between the two parasites which were able to coexist and communicate with their hosts in ecological contexts (with a high overlap in time and space) and cause interspecific competition and intraguild predation. Complex interspecific relationships between parasites and their insect hosts involve multiple factors and are affected by their ecological and evolutionary context. A parasitoid Sclerodermus guani (Hymenoptera: Bethylidae) and an entomopathogenic fungus Beauveria bassiana (Hypocreales: Cordycipitaceae) shared the same host in nature, Monochamus alternatus (Coleoptera: Cerambycidae). They often encountered the semi-enclosed microhabitat of the host larvae or pupae. We tested the survival and reproduction of the parasitoid's parent and its offspring fitness under different concentrations of B. bassiana suspension. The results show that S. guani parent females carrying higher concentrations of the pathogen shorten the pre-reproductive time and regulate their own fertility and their offspring's survival and development. This minimal model of the interspecific interactions contains three dimensionless parameters, vulnerability (θ), dilution ratio (δ), and PR, which were used to evaluate the mortality effect of the parasitoid S. guani on its host M. alternatus under the stress of the entomopathogenic fungus B. bassiana. We compared the infection and lethal effect of the fungus B. bassiana with different concentrations to the parasitoid S. guani and the host larvae M. alternatus. At higher concentrations of the pathogen, the parasitoid parent females shorten the pre-reproductive time and regulate their own fertility and their offspring's survival and development. At moderate concentrations of the pathogen, however, the ability of the parasitoid to exploit the host is more flexible and efficient, possibly reflecting the potential interspecific interactions between the two parasites which were able to coexist and communicate with their hosts in ecological contexts (with a high overlap in time and space) and cause interspecific competition and intraguild predation. [ABSTRACT FROM AUTHOR]

Butenyl-spinosyn, a secondary metabolite produced by Saccharopolyspora pogona , exhibits strong insecticidal activity than spinosyn. However, the low synthesis capacity and unknown metabolic characteristics of butenyl-spinosyn in wild-type S. pogona limit its broad application and metabolic engineering. Here, we showed that S. pogona exhibited increased glucose consumption ability and growth rate compared with S. spinosa , but the production of butenyl-spinosyn was much lower than that of spinosyn. To further elucidate the metabolic mechanism of these different phenotypes, we performed a comparative proteomic and metabolomic study on S. pogona and S. spinosa to identify the change in the abundance levels of proteins and metabolites. We found that the abundance of most proteins and metabolites associated with glucose transport, fatty acid metabolism, tricarboxylic acid cycle, amino acid metabolism, energy metabolism, purine and pyrimidine metabolism, and target product biosynthesis in S. pogona was higher than that in S. spinosa. However, the overall abundance of proteins involved in butenyl-spinosyn biosynthesis was much lower than that of the high-abundance protein chaperonin GroEL, such as the enzymes related to rhamnose synthesis. We speculated that these protein and metabolite abundance changes may be directly responsible for the above phenotypic changes in S. pogona and S. spinosa , especially affecting butenyl-spinosyn biosynthesis. Further studies revealed that the over-expression of the rhamnose synthetic genes and methionine adenosyltransferase gene could effectively improve the production of butenyl-spinosyn by 2.69- and 3.03-fold, respectively, confirming the reliability of this conjecture. This work presents the first comparative proteomics and metabolomics study of S. pogona and S. spinosa , providing new insights into the novel links of phenotypic change and metabolic difference between two strains. The result will be valuable in designing strategies to promote the biosynthesis of butenyl-spinosyn by metabolic engineering. [ABSTRACT FROM AUTHOR]

Male preference for mating with large females and its benefits on fitness have been shown in several animal taxa. However, the mechanisms underlying this preference are less well known. Dendroctonus valen s, a primarily monogamous bark beetle whose females initiate tunnels beneath the bark of host trees, provides a useful system for testing how male mate choice is based on size. Field observations and laboratory experiments demonstrated that D. valens males preferentially entered tunnels containing large females, and that large females were more fecund than small females. Behavioural assays showed that males could discern tunnel size, and preferred larger artificially constructed tunnels in a two-choice assay. Males were also able to walk more quickly through larger diameter tunnels. Volatiles and chirping sounds associated with females were also analysed. Female body size was positively associated with the intensity of the female's chirp, but not with the quantity of pheromones released. Playback of this chirp showed males preferred female-produced sound to a silent control, and that males could discriminate between soft and loud sounds. Male D. valens appear to have evolved strategies of mate selection by relying on dual cues, tunnel size and acoustic signals, to obtain a large partner to increase fitness. [ABSTRACT FROM AUTHOR]

Attack from insect herbivores poses a major threat to plant survival, and accordingly, plants have evolved sophisticated defence systems. Maize is cultivated as a staple crop worldwide, and insect feeding causes large production losses. Despite its importance in agriculture, little is known about how maize reacts to insect herbivory. Taking advantage of advances in sequencing and mass spectrometry technology, we studied the response of maize to mechanical wounding and simulated Mythimna separata (a specialist insect) herbivory by applying its oral secretions (OS) to wounds. In comparison to the responses induced by mechanical wounding, OS elicited larger and longer-lasting changes in the maize transcriptome, proteome, metabolome and phytohormones. Specifically, many genes, proteins and metabolites were uniquely induced or repressed by OS. Nearly 290 transcription factor genes from 39 families were involved in OS-induced responses, and among these, more transcription factor genes were specifically regulated by OS than by wounding. This study provides a large-scale omics dataset for understanding maize response to chewing insects and highlights the essential role of OS in plant-insect interactions. [ABSTRACT FROM AUTHOR]

The red turpentine beetle, Dendroctonus valens LeConte (Coleoptera: Curculionidae: Scolytinae), is one of the most destructive invasive forest pests in China. Little is known about the biological characteristics of red turpentine beetle. Analysis of the frequency distribution has shown that red turpentine beetle's larvae have five instars with head capsule width 0.64, 0.83, 1.16, 1.45, and 1.99 mm, respectively. The ratio of increase of head capsule width is 1.33, which is consistent with Dyar's rule. The duration of egg, larval, and pupal is ≈10, 84, and 10 d, respectively. After its emergence, the callow adult darkens to the typical reddish brown by the time it is ready to leave the tree; beetles begin to “fly out” at the 10th day and continue for 20 d, with the peak flight taking place on the 21st day. Pairs of red turpentine beetles introduced into pine bolts produced 106 offspring. Such basic information is important for developing management strategies to combat this invasive bark beetle in China. [ABSTRACT FROM PUBLISHER]

Abstract: The effects of transgenic Bt cotton on the overwintering generation of the cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), are unknown. We hypothesized that a Bt cotton diet may adversely affect fitness of this generation and examined fresh weight, lipids, glycogens, low-molecular-weight sugars and SCPs (supercooling points) of pupae, as well as survival of larvae, diapausing pupae and adult emergence in comparison with controls. Field and laboratory experiments showed that larvae fed on Bt cotton had a decreased pupation rate, and fewer entered diapause and emerged as adults compared with larvae fed non-Bt cotton. Furthermore, larvae fed Bt cotton had reduced pupal weight, glycogen content and trehalose levels both in diapausing and in non-diapausing pupae, and only diapausing pupae had an increased SCP compared to controls. The SCPs of diapausing pupae reared on Bt cotton were significantly higher than those reared on non-Bt cotton. The trehalose levels of diapausing pupae reared on Bt cotton were significantly lower than those of larvae reared on non-Bt cotton. Thus, these results suggest that a Bt cotton diet weakens the preparedness of cotton bollworm for overwintering and reduces survival of the overwintering generation, which will in turn reduce the density of the first generation in the following year. Effects of transgenic Bt cotton on the overwintering generation of cotton bollworm appear to have significantly contributed to the suppression of cotton bollworm observed throughout northern China in the past decade. [Copyright &y& Elsevier]

Abstract: Facultative diapause, a strategy that allows insects to initiate additional generations when conditions are favorable or to enter diapause when they are not, has a profound effect on the ecology and evolution of species. Most previous studies have concentrated on the role of photoperiod and temperature in inducing facultative diapause in insects. In contrast, here we studied pupal diapause mediated by larval host plants in the cotton bollworm Helicoverpa armigera, and confirmed that pupal weight is a critical factor. Two groups of third instar H. armigera larvae, kept at 25°C with L:D=8:16 and 20°C with photoperiod of L:D=8:16, respectively, were fed on six host plants and on artificial diet (as a control) to determine how larval host plants affect diapause incidence and related traits (such as pupal weight and developmental duration). The data showed larval host plants affected diapause incidence significantly and the effects could be masked by low temperature. Further analysis showed that pupal size, not the length of the sensitive stage, affected the decision to enter diapause. In a further experiment, third-instar to final-stage larvae deprived of artificial diet for 2 days demonstrated a direct relationship between pupal weight and diapause incidence. These results suggest that larval host plants, by affecting pupal size, may influence diapause occurrence in H. armigera. This has important adaptive significance for both over-wintering survival and the possibility for completing an additional generation. [ABSTRACT FROM AUTHOR]

Abstract: Laboratory colonies of cotton bollworm larvae, Helicoverpa armigera, were kept at 20°C under a photoperiod of L:D=10:14 and fed on three host plants (cotton, tobacco, kidney bean) and an artificial diet (control) to determine the dynamic effects of larval host quality on over-wintering physiology and mortality. Energy reserves (glycogen and lipid), super-cooling points (SCPs), low-molecular-weight sugars, temperature, and mortality were monitored from November 2002 to April 2003. Lipid content did not change much for each group during over-wintering, but differed according to larval host plants. Larval host plants obviously influence the amount of glycogen, as does time of year: glycogen was lowest in February and increased in early spring. During winter, the mean pupal SCPs increased the most in February, then decreased, and were also affected by larval host plant, i.e. over-wintering pupae reared on kidney bean had the highest SCPs. Levels of glycerol and inositol differed significantly among host plants and months, which peaked in February. Pupal mortality also varied according to larval host plants and time: pupae reached their highest mortality in March and showed host plant differences in January. Records show that February was the coldest month during the period we observed, which corresponded closely to changes in over-wintering characteristics. [Copyright &y& Elsevier]

Abstract: Laboratory colonies of cotton bollworm larvae, Helicoverpa armigera, kept at 20°C under a photoperiod of L:D=10:14 were fed on five host plants (cotton, corn, kidney bean, tobacco and tomato) and an artificial diet (control) to determine the effects of larval host quality on survival and pupal over-wintering preparedness. A separate experiment showed that diapausing pupae weighed more and contained greater nutrient stores than did non-diapausing pupae. Diapausing pupae reared on different host plants showed significant differences in terms of over-wintering reserve storage, and degree of cold-hardiness (extent of low-molecular-weight substances and SCPs), and survivorship. The more nutrients the host plant had, the more the pupae weighed and the higher the levels of total lipids and glycogen. Body water content was also significantly affected by larval food quality. The mean pupal super-cooling capacities varied significantly from −16.7 to −18.9°C according to host plants the larvae feed on, and these significantly related to water content, pupal weight, lipid and glycogen content, and the levels of glycerol. Levels of trehalose, glycerol, and inositol, which were mainly low-molecular-weight substances, showed no significant differences among different host plants, except for trehalose. Pupal mortality varied from 39.7% on corn to 3.3% on the artificial diet, which was significantly related to pupal weight, total lipid content, trehalose levels, and super-cooling points. These results suggest that larval food quality can affect survival and influence the over-wintering preparedness of the cotton bollworm. [Copyright &y& Elsevier]

Abstract: Summer diapause in the cotton bollworm, Helicoverpa armigera (Hübner), which prolongs the pupal stage, particularly in males, is induced by high temperatures. In the laboratory, summer-diapausing pupae of H. armigera were induced at high temperatures (33–39°C) with a photoperiod of LD8:16; winter-diapausing and non-diapausing pupae, cultured at 20°C with a photoperiod of LD8:16 and at 27°C, LD16:8, respectively, acted as a control. Retention time of eye spots, weight, and lipid and glycogen levels were compared. At high temperatures, both body weight and energy storage capacity were much higher in summer-diapausing pupae than in non-diapausing pupae reared at 33–39°C. At temperatures (>33°C) high enough to maintain summer diapause, the eye spots of summer-diapausing pupae did not move during the 30-day experiment. However, eye spots of summer-diapausing pupae placed at 30°C began to move about 10 days after they were transferred, significantly later than in non-diapausing pupae reared at 33–39°C or non-diapausing pupae reared at 27°C, which initiated eye spot movement 2 days after pupation. The differences in retention time of eye spots between summer- and winter-diapausing pupae shows that winter diapause is more intense than summer diapause in this insect. The weight loss, and lipid and glycogen metabolism curves indicate that the summer-diapausing pupae''s metabolism is very low. We conclude that summer diapause in the cotton bollworm is a true diapause and that the summer diapause enables the cotton bollworm to withstand the high temperatures of summer. [Copyright &y& Elsevier]

Butenyl-spinosyn is a highly effective and broad-spectrum biopesticide produced by Saccharopolyspora pogona . However, the yield of this compound is difficult to increase because the regulatory mechanism of secondary metabolism is still unknown. Here, the transcriptional regulator Sp13016 was discovered to be highly associated with butenyl-spinosyn synthesis and bacterial growth. Overexpression of sp13016 improved butenyl-spinosyn production to a level that was 2.84-fold that of the original strain, while deletion of sp13016 resulted in a significant decrease in yield and growth inhibition. Comparative proteomics revealed that these phenotypic changes were attributed to the influence of Sp13016 on the central carbon metabolism pathway to regulate the supply of precursors. Our research helps to reveal the regulatory mechanism of butenyl-spinosyn biosynthesis and provides a reference for increasing the yield of natural products of Actinomycetes .

Tumor growth and metastasis depend on angiogenesis. Thus, inhibiting tumor angiogenesis has become promising cancer therapeutic strategy in recent years. Tumstatin is a more powerful angiogenesis inhibitor than endostatin. Anti-angiogenic active fragment encoding amino acids 45-132 (Tum-5) of tumstatin was subcloned into four different inducible expression vectors and successfully solubly expressed in Escherichia coli BL21 (DE3) in this study. Subsequently, an anaerobic inducible expression vector was constructed under Vitreoscilla hemoglobin gene promoter Pvhb in E. coli Nissle 1917 (EcN). The secretory expression of Tum-5 in the engineered bacterium was determined in vitro and in vivo by Western blot or immunochemistry. The anti-tumor effect detection demonstrated that EcN could specifically colonize the tumor, and B16 melanoma tumor growth was remarkably restrained by EcN (Tum-5) in mice bearing B16 melanoma tumor. Abundant infiltrating inflammatory cells were observed in tumor areas of the EcN-treated group through hematoxylin and eosin staining, with a relatively reduced expression of endothelial marker platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31) by immunofluorescence in tumor sections of EcN (Tum-5)-treated mice. No significant morphological differences were observed in the liver, kidney and spleen between EcN-treated mice and the control group, indicating that EcN was cleared by the immune system and did not cause systemic toxicity in mice. These findings demonstrated that the gene delivery of Tum-5 to solid tumors could be an effective strategy for cancer therapy., Competing Interests: CONFLICTS OF INTEREST No potential conflicts of interest, including financial and personal interests, is involved in the publication.

Several studies suggest that some bark beetle like to attack large trees. The invasive red turpentine beetle (RTB), Dendroctonus valens LeConte, one of the most destructive forest pests in China, is known to exhibit this behavior. Our previous study demonstrated that RTBs preferred to attack large-diameter trees (diameter at breast height, DBH ≥30 cm) over small-diameter trees (DBH ≤10 cm) in the field. In the current study, we studied the attacking behavior and the underlying mechanisms in the laboratory. Behavioral assays showed that RTBs preferred the bark of large-DBH trees and had a higher attack rate on the bolts of these trees. Y-tube assays showed that RTBs preferred the volatiles released by large-DBH trees to those released by small-DBH trees. Subsequent analysis revealed that both large- and small-DBH trees had the same composition of monoterpenes, but the concentration of each component differed; thus it appeared that the concentrations acted as cues for RTBs to locate the right-sized host which was confirmed by further behavioral assays. Moreover, large-DBH pine trees provided more spacious habitat and contained more nutrients, such as nitrogen, than did small-DBH pine trees, which benefited RTBs' fecundity and larval development. RTBs seem to have evolved mechanisms to locate those large hosts that will allow them to maximize their fitness. Monoterpene variation mediated attack preference implies the potential for the management of RTB.

Optimality models of host-parasitoid relationships have traditionally assumed that host quality increases as a function of host size at parasitism. However, trade-offs may play a crucial role in species evolution and should be found in host-parasitoid interactions where the host quality may differ between different sizes. Here, we investigated the effects of host size differences of Monochamus alternatus larva on foraging decisions, parasitism and related fitness in a gregarious ectoparasitoid, Sclerodermus harmandi. Two-choice and non-choice experiments were conducted with M. alternatus larvae to evaluate preference and performance of S. harmandi, respectively. Results from two-choice test showed that adult females prefer to attack large larvae rather than small larvae. In no-choice tests, adult females needed more time to paralyze large larvae than small larvae before laying eggs on the body surface of M. alternatus larvae and had lower survival and parasitism rate on those large larvae. Foraging decisions of S. harmandi led to the selection of the most profitable host size for parasitoid development, which showed more offspring gained on large M. alternatus larvae than on small larvae and got higher body weight on those large hosts. This study demonstrates the existence of trade-off occurring during host-parasitoids interactions according to host size related quality.