Larval Body Weight Research Articles

Identification and expression profiles of gustatory receptor genes in Bactrocera minax larvae (Diptera: Tephritidae): Role of BminGR59f in larval growth.

Insects employ various types of gustatory receptors (GRs) to identify nutrient-rich food and avoid toxic substances. The larval gustatory system is the critical checkpoint for food acceptance or rejection. As a specialist herbivore, the larvae of Bactrocera minax feed only on unripe citrus fruits. However, how larvae use GRs to check and adapt to the secondary metabolites in unripe citrus fruits remains unknown. In this study, we first performed developmental expression profiles showing that most BminGRs genes were highly expressed in 1st and 2nd instar larvae and that tissue-specific expression indicated high expression of most BminGRs genes in the mouthparts of 2nd instar larvae. Furthermore, we found that silencing BminGR59f by RNA interference (RNAi) affected the growth of 2nd instar B. minax larvae. Hesperidin and naringin were screened as ligands of BminGR59f via RNAi and cell calcium imaging, and the combination of these two flavones increased the body weight of larvae. In summary, we identified a novel gustatory perception pattern in B. minax for detecting hesperidin and naringin, which boosted the growth of B. minax larvae. These results shed light on how specialist herbivores detect and adapt to host metabolites in adverse environments depending on larval GRs.

Effect of Dietary Meat Content on Weight Gain, Mortality, and Pre-Pupal Rate in Black Soldier Fly (Hermetia illucens) Larvae.

Simple SummaryRecently, using insects to process food waste has attracted much attention from researchers. In this study, we investigated the extent to which meat can be included in the diets of immature black soldier flies. Based on our results, it was found that the meat content should be less than 80%. In addition, previous studies have shown that the protein and fat content of immature black soldier fly diets are important for growth and survival. However, it became clear in the present study that it is necessary to pay more attention to the nitrogen-free extract content of a diet than to the protein and fat content.This study aimed to determine the protein content and the ratio of meat that can be added to the diet of black soldier fly (BSF) larvae for the sustainable recycling of food waste using insects. We conducted experiments feeding refined diets to BSF larvae with adjusted protein content and diets with minced pork, and analyzed the correlations between dietary nutrients and larval weight gain, mortality, and pre-pupal rate. The nutrient that was positively correlated with increased larval body weight and pre-pupal rate in both experiments was nitrogen-free extract (NFE). Diets with high concentrations of minced pork showed higher mortality of BSF larvae and were negatively correlated with dietary NFE content. It has been suggested that BSF larvae have reduced body weight and survival due to excessive protein and fat in their diet. Depending on the raw material and ratio of food waste, it may be necessary to adjust dietary protein and fat contents before treatment. The results of this study suggest that the NFE content of a larval diet influences the larval weight gain, mortality, and pre-pupal rate of BSF larvae in a great extent, a finding that has not been reported by previous studies.

Effect of Tachinid Parasitoid Exorista japonica on the Larval Development and Pupation of the Host Silkworm Bombyx mori.

The Tachinidae are natural enemies of many lepidopteran and coleopteran pests of crops, forests, and fruits. However, host-tachinid parasitoid interactions have been largely unexplored. In this study, we investigated the effects of tachinids on host biological traits, using Exorista japonica, a generalist parasitoid, and the silkworm Bombyx mori, its lepidopteran host, as models. We observed that E. japonica parasitoidism did not affect silkworm larval body weight gain and cocooning rate, whereas they caused shortened duration of molting from the final instar to the pupal stage, abnormal molting from larval to pupal stages, and a subsequent decrease in host emergence rate. Moreover, a decrease in juvenile hormone (JH) titer and an increase in 20-hydroxyecdysone (20E) titer in the hemolymph of parasitized silkworms occurred. The transcription of JH and 20E responsive genes was downregulated in mature parasitized hosts, but upregulated in parasitized prepupae while Fushi tarazu factor 1 (Ftz-f1), a nuclear receptor essential in larval ecdysis, showed dramatically reduced expression in parasitized hosts at both the mature and prepupal stages. Moreover, the transcriptional levels of BmFtz-f1 and its downstream target genes encoding cuticle proteins were downregulated in epidermis of parasitized hosts. Meanwhile, the content of trehalose was decreased in the hemolymph, while chitin content in the epidermis was increased in parasitized silkworm prepupae. These data reveal that the host may fine-tune JH and 20E synthesis to shorten developmental duration to combat established E. japonica infestation, while E. japonica silences BmFtz-f1 transcription to inhibit host pupation. This discovery highlights the novel target mechanism of tachinid parasitoids and provides new clues to host/tachinid parasitoid relationships.

Influence of 50 Hz electromagnetic frequency on oxidative stress and morphological characteristics in mosquito-borne filariasis Culex pipiens

• The larvae of Culex pipiens were exposed to EMF frequency (50 Hz). • The biochemical and morphological changes in Culex pipiens were estimated. • The larval body weight and total protein in EMF treated groups were significantly decreased compared to control. • Antioxidant enzymes activity in EMF treated groups were decreased significantly compared to the control. • Both 500 & 1000 mT caused distinct malformations to the larval body parts. The electromagnetic field (EMF) is a vital issue in research, but its use as an alternative technique for insect management is still in its beginnings. The study aimed to evaluate the effects of exposure to the electromagnetic field on the biochemical analysis and morphological characteristics in Culex pipiens . Therefore, the third instar larvae were exposed to EMF frequency (50 Hz) at different intensities (250, 500, 1000 mT) for 1 h during four successive days. After end exposure to EMF, the biochemical analysis, oxidative stress parameters, body weight, and morphological features were investigated. The results showed that larval body weight and total protein content were decreased significantly in all treated groups compared to controls. The total lipid content significantly decreased at 500 & 1000 mT exposure, while the treatment group exposed to EMF at 250 mT was not statistically different compared to control. At a high intensity of EMF 1000 mT all oxidative stress parameters; catalase (CAT) and Glutathione S-transferase (GST) activity and lipid peroxidation level (MDA) were decreased significantly compared to the control. On the other hand, at a low intensity (250 mT), CAT and GST activity was significantly increased, while MDA content was not statistically changed. Scanning electron microscopy showed that both 500 & 1000 mT caused distinct malformations to the larval body parts, mouthparts, thorax and abdomen with last abdominal structures. In conclusion, the results demonstrated that EMF exposure is a considerable stress factor that affects oxidative state and morphological features in mosquitoes and give hope that EMF will be used as an alternative method for Culex pipiens vector control.

Development of Chrysomya albiceps (Wiedemann, 1819) (Diptera: Calliphoridae) from the Jazan region of Southwest Saudi Arabia under different laboratory temperatures: applications in forensic entomology

BackgroundChrysomya albiceps (Wiedemann, 1819) (blowflies), family Calliphoridae, is important in forensic entomology, where the minimum and maximum postmortem intervals (PMI) are estimated on the basis of the developmental stages of Diptera larvae that consume dead tissue. The present study was designed to estimate the effects of different ambient temperatures (20, 25, and 30 °C) under controlled laboratory conditions on the developmental stages of C. albiceps from the Jazan region, Saudi Arabia.ResultsThe present study showed that the larval body weight and length were significantly increased when larvae were reared at 30 °C compared with corresponding values at 24 h, 48 h, and 72 h at rearing temperatures of 20 °C and 25 °C; however, the weight and length were significantly decreased compared with corresponding values at 96 h at 20 °C and 25 °C. The pupation time was inversely related to the rearing temperature, occurring at 144, 124, and 120 h at rearing temperatures of 20 °C, 25 °C, and 30 °C, respectively. The pupal weight and length were significantly increased in larvae reared at 30 °C compared with those reared at 20 °C and 25 °C. At 20 °C, 25 °C, and 30 °C, larval durations of 5.00, 5.00, and 4.00 days were recorded, respectively. Pupae and adults showed gradual decreases in life stage durations, at 6.00, 5.30, and 4.80 days in pupae and 20.00, 18.70, and 16.90 days in adults, with increasing rearing temperatures. Average adult longevity at 30 °C (194.40 h) was significantly less than adult longevity at 20 °C (216.00 h) and 25 °C (204.60 h). The results showed an inverse relation between durations of developmental stages and rearing temperatures.ConclusionsInsect laboratory colonization for the determination of biological characteristics of insects is economically viable for forensic entomology and as a technique for evaluating insect evidence.

Health risks of sulfentrazone exposure during zebrafish embryo-larvae development at environmental concentration

Knowledge about the negative effects and mechanism of sulfentrazone (SUL) on aquatic early life stages is still limited. Here we investigated the lethal and sub-lethal effects of SUL during zebrafish embryo-larvae development. Results demonstrated that the 96 h and 120 h-LC50 of SUL to embryonic zebrafish was 2.02 mg/L, and the 30 d-LC50 was 0.899 mg/L after embryos exposed to SUL for 30 d. High concentrations of SUL delayed yolk sac absorption, disordered the hatching and heart rate during zebrafish embryonic stage, while 0.0100–0.100 mg/L SUL had no phenotypic changes on embryonic development, but decreased the body weight of larvae after 30 d exposure. RNA-seq identified 321, 394 and 727 differentially expressed genes in larvae after embryos exposed to 0.0100 mg/L, 0.0400 mg/L and 0.400 mg/L SUL for 30 d, found that the transcriptional profiles involved in heart development and endocrine disruption were simultaneously influenced by different concentrations of SUL, such as adrenergic signaling in cardiomyocytes, cardiac muscle contraction, cell adhesion molecules and steroid biosynthesis. Biochemical analysis showed that SUL increased the levels of E2, T3 and TSH, induced the activities of mitochondrial complex IV, cytochrome c oxidase, Ca2+-ATPase, total Na+K+-ATPase and Ca2+Mg2+-ATPase, and decreased ATP formation after embryos exposed to SUL for 5 d and 30 d. Further comprehensive analysis demonstrated that SUL caused more significantly alteration on the transcript, level or activity of the key elements involved in heart development and endocrine disruption after 30 d exposure, indicated long-term SUL exposure might cause more negative effects on zebrafish at doses below the presumed no-observed-adverse-effect level during early life development. The results inferred the environmental concentration of SUL might cause potential cardiac and endocrine health risk in zebrafish later life stages, also facilitated a better understanding of the sub-lethal effects and molecular mechanism of SUL on aquatic organism.

Effect of the energy content of diets on the development and quality of the fat reserves of larvae and reproduction of adults of the black soldier fly, Hermetia illucens (Diptera: Stratiomyidae)

Hermetia illucens is a sustainable and an increasingly bioeconomical source of nutrients for farm animals. It is still necessary, however, to improve our knowledge of the biological features of this species in order to maximize its use. The aims of this research were to evaluate the effect of the energy level of rearing diets on its body weight and fat-body reserves. The quantity and quality of the fats storred by the non-feeding stages of this insect and its reproductive performances were also studied. A control diet (CD - Gainesville diet) and three diets with progressively greater energy contents (kcal/kg ME) were formulated. The increase was achieved by including different amounts of maize, 40% (ED1), 60% (ED2) and 80% (ED3), in these three diets. Abother diet (ED4) consisted of fruit and vegetable waste. The results indicate that the body weight of larvae, prepupae, pupae and adult flies, as well as fat content of the larvae increased significantly (p ˂ 0.01) with increase in the energy content of the diets. There was a positive Pearson correlation between energy content of diets and body weight of adult flies. The heaviest egg clutches with the highest number of eggs/clutch (p ˂ 0.01) were laid by flies reared on the diets with the highest energy content. The quality of the fat stored by larvae did not influence the weight and number of egg laid.

The effects of cadmium on the development of Drosophila and its transgenerational inheritance effects

A new focus in toxicology research is the impact of parental exposure to environmental toxic substances on the characteristics of offspring. In the present study, newly produced eggs of Drosophila melanogaster were treated with different concentrations of cadmium (0, 1, 2, 4, 8 mg/kg) to study the effects of development. The results showed that cadmium changed the larval body length and weight, prolonged the pupation and eclosion time, and changed the relative expression levels of development-related genes (baz, β-Tub60D, tj). Furthermore, the parental Drosophila (F0) were treated with cadmium (4.5 mg/kg) from egg stage, and when grows to adults, they mated in standard medium to produce the de-stressed offspring (F1-F4) to assess the transgenerational effects of developmental delay. The results showed that the delayed effects of the pupation and eclosion time could be maintained for two generations, and the inhibiting effects of juvenile hormone (JH) and ecdysone (20-hydroxyecdysone, 20E) could be maintained for two or three generations. More importantly, cadmium increased the expression of DNA methylation-related genes (dDnmt2, dMBD2/3) in the ovaries (F0-F2) and testicles (F0 and F1). In addition, cadmium accumulated in parental Drosophila (F0) was not transmitted to offspring through reproductive pathway. These results demonstrate that the developmental toxicity caused by cadmium could be transmitted to the de-stressed offspring, and the observed transgenerational inheritance effects may be associated with epigenetic regulation, underscoring the need to consider fitness of future generations in evaluating the toxicity and environmental risks of cadmium.

Growth Performance of Hermetia illucens and Tenebrio molitor in Different Organic Waste Biconversion Process

The amount of organic waste in Indonesia has increased. One solution to reduce the amount of organic waste is to use the concept of bioconversion. Bioconversion can be done using the larvae of insects Hermetia illucens and Tenebrio molitor. The type of organic waste and the amount of organic waste given affects the change in body weight of the larvae Hermetia illucens and Tenebrio molitor (P>0.01). The largest change in the body weight of Hermetia illucens larvae occurs in the market waste media and the largest change in the body weight of Tenebrio molitor larvae occurs in chicken manure. The survival rates of Hermetia illucens and Tenebrio molitor are highest in the market waste media.

Probiotic supplementation mitigates the developmental toxicity of perfluorobutanesulfonate in zebrafish larvae

Perfluorobutanesulfonate (PFBS) is an emerging pollutant of international concern, which is found to impair the early embryonic development of fishes. In the context of ubiquitous and persistent pollution, it is necessary to explore mitigatory strategies against the developmental toxicity of PFBS. In this study, zebrafish larvae were acutely exposed to 0, 1, 3.3 and 10 mg/L of PFBS till 168 h post-fertilization (hpf), during which probiotic Lactobacillus rhamnosus bacteria were administered via the exposure media. After the singular or combined exposure, interaction between PFBS and probiotics on the growth of zebrafish larvae was measured. PFBS exposure significantly decreased the larval body weight, weight gain and specific growth rate, while probiotic supplementation efficiently inhibited the growth retardation caused by PFBS. Furthermore, PFBS and probiotic combinations remarkably activated the antioxidant capacity to timely scavenge the reactive oxidative species and protect the larvae from lipid peroxidation. Biochemical assay and fluorescent staining verified that PFBS exposure significantly promoted the production of bile acids, which were further enhanced by the probiotics. In coexposed zebrafish larvae, up-regulation of peroxisome proliferator-activated receptor (PPARb) would enhance the β-oxidation of fatty acids to meet the energy demand from larval growth, subsequently decreasing fatty acid concentrations. In addition, probiotic supplements masked the dysbiosis of PFBS and potently shaped the gut microbiota, which closely modulated the production of bile acids. Overall, the present findings underline the beneficial effects of probiotics to protect the developing larvae from the aquatic toxicities of PFBS, thus highlighting the potential application values of probiotic recipe in aquaculture and ecological reservation.

Sublethal Effects of the Microbial-Derived Insecticide Spinetoram on the Growth and Fecundity of the Fall Armyworm (Lepidoptera: Noctuidae).

The fall armyworm, Spodoptera frugiperda (J. E. Smith), is one of the most important pests in tropical and subtropical regions of American. S. frugiperda was first detected in Southern China in January 2019, and then subsequently invaded in 26 provinces. Spinetoram widely used for pest management is recommended for S. frugiperda control. The sublethal effects of spinetoram on S. frugiperda were investigated in the present study. The toxicity of spinetoram against S. frugiperda larvae was determined after one oral dose of spinetoram at sublethal concentration. The results showed that spinetoram LC10 and LC30 were 0.011 and 0.044 mg/liter for the larvae, respectively. Spinetoram at sublethal concentration significantly increased developmental time but reduced larval body weight. In addition, spinetoram had a post-exposure effect on pupal weight, but not on pupal duration, pupation rate, emergence rate, eggs number, or adults longevity. In conclusion, the sublethal effects of spinetoram could negatively affect the growth and development of S. frugiperda that have important implications for pest management.

Immunoreactivity of somatolactin (SL)-producing cells during larval development of Nile tilapia

ABSTRACTIntroduction: A growing body of evidence confirmed the involvement of somatolactin (SL) in various physiological processes including the acid-base as well as calcium regulation, fat metabolism and osmoregulation. However, less is known about the immunoreactivity of SL- producing cells during developmental stages of Nile tilapia, Oreochromis niloticus. Aim of the work: The aim of the present work was to examine the immunoreactivity of SL-producing cells during different developmental larval stages of Nile tilapia, O. niloticus. Material and methods: We performed immunohistochemical technique using specific antibody against chum salmon SL to identify the anatomical distribution and change in the activity of SL-producing cells accompanied the different larval stages of Oreochromis niloticus, and study the possible involvement of this hormone in the early endocrine integration. Results: The present immunocytochemical assessments revealed a few and dispersed numbers of SL-positive cells at the first day after hatching. Moreover, we observed a gradual increase in the activity of SL-positive cells in the pituitary gland as reflected with the increased cell number and size as well as SL immunoreactivity concomitant with the continued larval development from the first day post-hatching onwards and reached the highest levels on day 35 post- hatching. In parallel to the advanced development of larvae, the number of SL-positive cells and the intensity of immunoreaction were clearly and gradually increased especially after the onset of exogenous feeding at 21-28 days post-hatching. Consequently, there is an obvious increase in both the larval body length and weight during the experimental period of rearing.Conclusion: The early appearance of SL-producing cells and the gradual changes in their immunoreactivity during development suggest crucial effects of this hormone in different physiological processes during larval rearing of O. niloticus especially in the period after yolk sac resorption.

Sublethal concentration of emamectin benzoate inhibits the growth of gypsy moth by inducing digestive dysfunction and nutrient metabolism disorder.

Gypsy moth (Lymantria dispar) is one of the most important pests in the world. Emamectin benzoate (EMB) is widely used in the control of agricultural and forestry pests. Here, we explored the sublethal effects of EMB on gypsy moths in order to better understand the toxicological mechanism of EMB. The sublethal concentration of EMB exposure significantly decreased the larvae body weight. To further explore the mechanism, indicators related to digestion and nutrient metabolism were detected. The results showed that EMB exposure caused midgut damage, reduced the activities of digestive enzymes and changed the content of sugar and amino acids. Moreover, the expression of insulin/phosphoinositide-3-kinase (PI3K)/forkhead box protein O (FoxO) pathway and sugar metabolism-related genes was abnormal. The expression of insulin receptor (InR), chico, PI3K, and protein kinase B (Akt) significantly reduced, and that of phosphatase and tensin homologue (PTEN) and FoxO increased. The expression of glycogen phosphorylase (GP) was upregulation and that of glycogen synthase (GS), trehalase (TRE) and trehalose-phosphate synthase (TPS) were downregulation. All results indicated that EMB inhibits the growth of gypsy moth by inducing midgut injury, digestive dysfunction and nutrient metabolism disorder. In addition, EMB caused midgut injury may be related to apoptosis or a collateral effect of the damage in other tissues, and more extensive and deeper research is still needed to investigate the detailed mechanism. Our finding strengthens the understanding of the sublethal effect of EMB, and provides a theoretical basis for the application of EMB in the prevention and control of gypsy moth.

Investigating Acute and Subchronic Effects of Neonicotinoids on Northwestern Salamander Larvae

This research investigated the adverse effects of neonicotinoids on the Northwestern salamander (Ambystoma gracile; NWS) after acute and subchronic exposures during early aquatic life stages via whole organism (i.e., growth, development) and molecular (i.e., gene expression) level endpoints. In a 96-h exposure, NWS larvae were exposed to four imidacloprid concentrations (250, 750, 2250, 6750µg/L) and a water control treatment, and no effects on survival, body weight, snout-vent length (SVL), and total body length were observed. However, a significant 1.70- and 2.33-fold decrease in thyroid receptor β (TRβ) mRNA expression levels were detected in the larvae exposed to 750 and 2250µg/L imidacloprid, respectively, compared with the larvae in the water control. In subsequent subchronic experiments, NWS larvae were exposed for 35days to imidacloprid alone and an equal part mixture of neonicotinoids (imidacloprid, clothianidin, and thiamethoxam (ICT)) at three concentrations (10, 100 and 1000µg total neonicotinoids/L) and a water control. In these experiments, there were no effects on larval survival, body weight, SVL, and total body length. However, advanced development of larvae in the 100µg/L imidacloprid treatment was observed compared with the control after 35-day imidacloprid exposure, providing some evidence of disruption of the thyroid endocrine axis at an environmentally relevant concentration. Ultimately, there is a paucity of studies conducted examining the sensitivity of salamanders to pollutants; thus, this study reports novel findings that will contribute to understanding the sensitivity of a Caudate amphibian model to a common environmental pollutant.

Adaptation of life-history traits and trade-offs in marine medaka (Oryzias melastigma) after whole life-cycle exposure to polystyrene microplastics

Microplastics are ubiquitous in marine environments and may cause unexpected ecological effects. This study adopted a whole life-cycle exposure to illuminate the impact of polystyrene microplastics on life-history strategies of marine medaka (Oryzias melastigma), including the hatching of embryos, growth and reproduction of F0 generation, and embryonic and larval development of F1 offspring. Microplastics accumulated on the eggshell and reduced embryonic hatching rate and larval body length and weight. Similarly, 150 days of microplastic exposure decreased body mass and gonadosomatic index of adult fish, but accelerated sexual maturity of female fish, showing a trade-off between growth and reproduction. Microplastic exposure also caused obvious histopathological damages to gonads and decreased egg productions and fertilization rates. Moreover, parental microplastic exposure induced elevated heartbeats, premature hatching, and slow growth in F1 offspring. Anti-oxidative stress response, sex hormone disruption, and disturbed transcription of steroidogenic genes in the reproductive axis could partially explain the reproduction impairment and transgenerational trade-offs. Furthermore, transcriptome analysis revealed that the steroid hormone biosynthesis and cytochrome P450 pathways in the testes of male fish were significantly affected after 20 μg/L microplastic exposure. These findings suggest that microplastic pollution may be an emerging threat to the sustainability of marine fish population.

The high adaptability of Hyphantria cunea larvae to cinnamic acid involves in detoxification, antioxidation and gut microbiota response

Hyphantria cunea is one of the most destructive invasive agricultural and forest pests worldwide. In order to better understand the adaptation mechanism of H. cunea larvae to secondary metabolites of their highly diversified host plants, the physiological function and detoxification ability of midgut, as well as the gut microbial community were investigated in H. cunea larvae fed with cinnamic acid-treated artificial diets. Our results showed that cinnamic acid treatment could not affect the growth and food utilization of H. cunea larvae, as evidenced by a non-significantly altered larval body weight and efficiency of conversion of ingested food. Evaluation of oxidative stress-related parameters (e.g. malondialdehyde and hydrogen peroxide) and midgut histopathology also clearly confirmed that cinnamic acid treatment caused no significant oxidative damage and pathological changes in the larval midgut. Variance analysis showed that cinnamic acid treatment significantly increased the content of non-enzymatic antioxidants (ascorbic acid and glutathione), the activity of antioxidant enzymes (superoxide dismutase and peroxidase) and detoxification enzyme (carboxylate esterase), as well as the abundance of several gut microbiota at the genus level (Hydrogenophaga and Acinetobacter) involved in the organic substance degradation in larval midgut. Further Pearson's correlation analysis revealed that these strongly altered gut microbiota at the genus level appeared to be significantly correlated with the detoxification and antioxidation parameters. These findings demonstrate the high adaptability of H. cunea larvae to cinnamic acid involves in detoxification, antioxidation and gut microbiota response, and indicate the existence of an extremely effective counter-defense mechanism for H. cunea larvae against the secondary metabolites of host plants.

Stem borers revisited: Host resistance, tolerance, and vulnerability determine levels of field damage from a complex of Asian rice stemborers

Yield losses from rice stem borers depend on the nature of the rice variety, the timing of attack, and the composition of the stem borer species assemblage. This study uses a range of phenotyping methods to distinguish different categories of herbivore-rice interaction that determine relative damage levels (dead heart and whitehead-panicles) and yield losses to varieties exposed to stem borers. Phenotyping studies were conducted in a greenhouse, screen house and field using two stem borer species (Scirpophaga incertulas [yellow stem borer - YSB] and Chilo suppressalis [striped stem borer - SSB]) and 12 rice lines. Only YSB displayed oviposition preferences across rice varieties. Both stem borer species performed better (greater survival, shorter development times, heavier pupae) on rice at vegetative compared to reproductive growth stages, and SSB was less capable than YSB of developing on rice at reproductive growth stages. Stem borer larval survival, body weight, development time, and tiller damage across different rice varieties in greenhouse experiments was poorly correlated between the two stem borer species and for each of the species on rice at two different plant growth stages (vegetative and reproductive). In contrast, rice tillering and yield responses to the two stem borer species were often highly correlated, but only when plants were attacked at the reproductive stage. Short-term, controlled experiments revealed aspects of host resistance and relative changes in plant biomass and yield in response to damage (condition change). However, the results from controlled environments and field-plots were not generally correlated because plant vulnerability, i.e., relative exposure to stem borer attack due to crop duration, largely determined field damage. We recommend that phenotyping studies should differentiate between the resistance, tolerance and vulnerability of rice lines to complexes of stem borers in a given region. Single stem borer species experiments under controlled environments are useful to gain knowledge of the nature of rice-stem borer interactions; however, field testing with comparative treatments, particularly under high soil fertilizer levels that increase plant attractiveness, are better for assessing the relative propensities of rice varieties to incur damage and yield losses due to complexes of stem borers.

Contributions to the Estimation of the Postmortem Interval Through the Length and Body Weight of Two Indigenous Species of South America: Lucilia ochricornis (Diptera: Calliphoridae) and Lucilia purpurascens.

The early arrival and colonization of species belonging to the family Calliphoridae (Insecta: Diptera) on a corpse represent one of the most reliable means of estimating minimum postmortem interval (PMImin). However, information on the development and life cycles of some Argentine species in this family is not complete. The objective of this work was to contribute new information regarding the larval body size of neotropical species that allow, through the construction of forensic methods, the estimation of a more precise and specific PMImin. This work was conducted on laboratory cultures of larvae of Lucilia ochricornis (Wiedemann) and Lucilia purpurascens (Walker) using as average temperatures: 13.4, 15.1, 22.6, and 23.3°C, which represent the four seasons of the year for the province of Salta. With this information, we constructed isomegalen diagrams and growth models for the obtained variables of larval length and body weight. The mean values of length and body weight differ between both species, indicating that L. purpurascens exceeded L. ochricornis in both variables. In contrast, within each species the mean length and weight remained unchanged between culture temperatures for the three larval instars. Isomegalen diagrams can be used for the entire range of temperatures worked in the laboratory, but the body size entered is approximate. The growth models allow the use of point data but are specific for each culture temperature used.

Parental Microbiota Modulates Offspring Development, Body Mass and Fecundity in a Polyphagous Fruit Fly.

The commensal microbiota is a key modulator of animal fitness, but little is known about the extent to which the parental microbiota influences fitness-related traits of future generations. We addressed this gap by manipulating the parental microbiota of a polyphagous fruit fly (Bactrocera tryoni) and measuring offspring developmental traits, body composition, and fecundity. We generated three parental microbiota treatments where parents had a microbiota that was non-manipulated (control), removed (axenic), or removed-and-reintroduced (reinoculation). We found that the percentage of egg hatching, of pupal production, and body weight of larvae and adult females were lower in offspring of axenic parents compared to that of non-axenic parents. The percentage of partially emerged adults was higher, and fecundity of adult females was lower in offspring of axenic parents relative to offspring of control and reinoculated parents. There was no significant effect of parental microbiota manipulation on offspring developmental time or lipid reserve. Our results reveal transgenerational effects of the parental commensal microbiota on different aspects of offspring life-history traits, thereby providing a better understanding of the long-lasting effects of host–microbe interactions.

Feeding effects of dsNPF interference in Ostrinia furnacalis

The corn borer is a world-wide agricultural pest. In this study, a high-efficiency RNAi method was explored to knock down the neuropeptide F (NPF) to determine if NPF regulates larval feeding in the Asian corn borer, Ostrinia furnacalis. Results showed that the expression peaks of npf mRNA in both midgut and fat body are at 28 h of early 5th instar larvae. When NPF was knocked down either by feeding dsNPF-containing artificial diet or direct dsNPF injection into the 5th instar larvae, npf expression was effectively inhibited in the midgut. Larval feeding, body weight and development time were significantly impacted. In contrast, the expression of the npf receptors npfr1 and npfr2 in fat body of 5th instar larvae was significantly increased by dsNPF injection. These results indicate that NPF can be effectively knocked down in O. furnacalis, and dsNPF by injection is an effective and fast way to silence npf expression. This study provides a critical basis for further exploration in mechanism of feeding regulation in O. furnacalis.