Abstract Global climate change and intensified human activities are increasingly affecting aquatic ecosystems, including Odonata, whose life cycles and physiology are closely linked to freshwater conditions such as temperature and food availability. While patterns influencing their distribution and abundance are well documented, physiological responses to anthropogenic stressors remain less understood. In this ex situ laboratory experiment, we examined the effects of water temperature and food availability on larvae of Aeshna cyanea Müller, 1764 (Odonata: Aeshnidae) by assessing body condition and immune function. Larvae were reared for 2 months at either 17 or 21°C, and within each temperature treatment, individuals were fed either three times per week or once per week to simulate food limitation. Elevated temperature reduced haemocyte density, but this effect depended on feeding frequency, with the negative effect of higher temperature being less pronounced under greater food availability. Food availability was a major driver of larval performance, with increased feeding promoting growth, fat stores, protein concentration and phenoloxidase (PO) activity. Conversely, there was marginal evidence that elevated temperature weakened the positive effect of increased feeding on fat accumulation. Faster growth was associated with lower protein concentration and PO activity, suggesting a potential allocation trade‐off between somatic growth, physiological condition and immune function. Together, these results show that temperature and food availability can influence larval performance both independently and interactively, providing insight into physiological mechanisms that may contribute to the vulnerability and decline of Odonata populations under changing environmental conditions.
Amino acids are essential nutrients that build proteins and regulate metabolic and developmental processes. Most are vital for development and reproduction, with their importance varying with the organism's life stage and reproductive status. This study examined the phagostimulation effects and reproductive impacts of individual essential amino acids and a mixture of non-essential amino acids in adult Mediterranean fruit flies, Ceratitis capitata. The amino acid solutions tested lacked lipids and vitamins, with fructose added to the PBS solution. The Phagostimulation Unit Bioassay (PUB) was used to measure diet ingestion, and reproductive parameters were recorded from individual couples. Several amino acids, including Methionine, Arginine, Phenylalanine, Threonine, Lysine and the non-essential amino acids mixture, showed stronger phagostimulation than fructose alone. Lysine and positive control increased egg production, whereas Arginine, Methionine and Histidine showed a high probability of constantly producing eggs throughout the investigated period. Eggs from female flies fed on the positive control, Arginine, Methionine, Phenylalanine and Histidine diets hatched more than those on fructose. A relationship was found between the constancy of egg production and phagostimulation. Results are discussed in terms of the roles of amino acids in reproduction and feeding neural activity. We highlight the implications for mass rearing and male competitiveness in sterile insect technique programs, particularly regarding amino acids like Arginine. Los amino & aacute;cidos (aa) son nutrientes esenciales requeridos para la s & iacute;ntesis de prote & iacute;nas, y como reguladores de procesos metab & oacute;licos y de desarrollo. La mayor & iacute;a son vitales para el desarrollo y la reproducci & oacute;n, pero su importancia var & iacute;a dependiendo del estadio del organismo y su estatus reproductivo. El presente estudio examina el efecto fago-estimulatorio y los impactos reproductivos de cada uno de los aa esenciales, y de una soluci & oacute;n-mezcla de aa no esenciales, en el adulto de la mosca de las frutas del Mediterr & aacute;neo, Ceratitis capitata. Las soluciones experimentales de aa diluidas en PBS solo inclu & iacute;an fructosa, y no inclu & iacute;an otros nutrientes como l & iacute;pidos y vitaminas. El Phagostimulation Unit Bioassay (PUB) fue utilizado para medir ingesti & oacute;n de las dietas, y los par & aacute;metros reproductivos fueron investigados en parejas de moscas. Algunos aa, como Metionina, Arginina, Fenilalanina, Treonina, Lisina, y la mezcla de aa no esenciales, resultaron ser fagos-estimuladores m & aacute;s potentes que la fructosa sola. Lisina y el control positivo, incrementaron la cantidad de huevecillos producidos por las parejas de moscas, mientras que Arginina, Metionina e Histidina afectaron positivamente la producci & oacute;n manteni & eacute;ndola constante durante todo el experimento. Los huevecillos producidos por hembras alimentadas con el control positivo, Arginina, Metionina, Fenilalanina e Histidina, eclosionaron significativamente m & aacute;s que huevecillos de hembras alimentadas solo con fructosa. Se observ & oacute; una relaci & oacute;n entre la constancia de producci & oacute;n de huevecillos y la fago-estimulaci & oacute;n de la dieta. Los resultados se discuten en relaci & oacute;n al rol de los aa en la reproducci & oacute;n y en la actividad neuronal del proceso de la ingesti & oacute;n. Enfatizamos las implicaciones del estudio en la cr & iacute;a masiva y en especial en el rol de Arginina en la competitividad de machos.
The growing use of pyrethroid insecticides raises concerns regarding their sub-lethal effects on beneficial non-target insects. This study evaluates the long-term neurophysiological and behavioural consequences of deltamethrin exposure through contaminated dung in the dung beetle Digitonthophagus gazella. Adult beetles were exposed to three sublethal concentrations of the LC50 (0.275 ppm): 1/20th (LD-0.014 ppm), 1/10th (MD-0.028 ppm) and 1/5th (HD-0.05 ppm), in comparison to control, for 10, 20 and 30 days. Results revealed a dose- and time-dependent decline in tunnelling activity and brood ball production. In comparison to controls, brood ball development decreased by up to 75% after 30 days at the highest dose (HD). Neurochemical investigations further demonstrated significantly (p < 0.01) reduced levels of dopamine (DA) (12%-26%), serotonin (5-HT) (8%-27%), acetylcholinesterase (AChE) activity (8%-40%) and nitric oxide (NO) levels (66%-85%), over the course of exposure. Neurotransmitter biosynthesis genes (ddc, 5-htpdc, chat, nos) and neuropeptide signalling genes (npf, npfr, it, itr, mip) were downregulated (2.5-9-fold) in conjunction with these neurochemical changes. The findings show that chronic sublethal exposure to deltamethrin is associated with altered neurochemical and transcriptional profiles and impaired nesting behaviour in D. gazella. These findings demonstrate the sensitivity of neuroendocrine pathways to pyrethroid exposure and emphasize the significance of assessing the effects of insecticides on ecologically beneficial insects.
Silk derived from the cocoon of the Bombyx mori (Linnaeus, 1758) plays an important role in the global economy. During the larval period, this insect feeds exclusively on mulberry leaves or on artificial diets that include mulberry leaves in their composition. Protein supplementation of silkworm diets has been explored as a strategy to optimize production performance. Silver nanoparticles (AgNPs) have been tested as a supplementation option, potentially stimulating insect feeding activity. This study's purpose was to analyse the effects of adding isolated and combined soy protein with silver nanoparticles incorporated on mulberry leaves during the B. mori feeding process. The group fed with AgNPs presented the highest body (5.29 g) and cocoon weight (2.19 g) among the groups tested. The group supplemented with silver nanoparticles and 2% isolated soy protein (S2Ag) exhibited a synergistic effect, resulting in lower leaf consumption, but with a silk conversion rate of 24.1%, similar to that of the control. These results are possibly related to differences in the expression of the silk genes fibroin and sericin. The AgNPs group showed higher expression of the heavy-chain fibroin (H-Fib) gene, and the S2Ag group showed higher expression of the sericin-1 and sericin-2 genes at the end of the 5th instar. These findings suggest potential practical applications of dietary supplementation with isolated soy protein and silver nanoparticles, both for larval development and for optimizing silk production, underscoring the importance of understanding the toxicological effects of these components in the context of sericulture.
Abstract The inability of black soldier fly larvae to efficiently extract and assimilate nutrients from diverse organic substrates leads to the production of small‐sized and poor‐quality larvae. Suboptimal nutrient digestion reduces overall biomass yield, survival and overall larval quality. Incorporating exogenous probiotics into black soldier fly larvae feeding systems is important in improving overall black soldier fly production. The study focused on the use of an exogenous Bacillus probiotic strain mixture to improve larval survival, growth and nutrient accumulation. A total of 1500 four‐day‐old black soldier larvae were manually counted in triplicate for each treatment and subjected to exogenous Bacillus probiotic strain mixture inoculation levels using a poultry feed. Four inoculation levels were used: P0 (0 colony‐forming unit [CFU]/kg) as a control, P1 (4 × 10 10 CFU/kg) as treatment 1, P2 (8 × 10 10 CFU/kg) as treatment 2 and P3 (12 × 10 10 CFU/kg) as treatment 3. The experiment was carried out in the laboratory under a completely randomised design. Larvae were reared under ambient conditions, with an average temperature of 28 ± 1.09°C and relative humidity of 70 ± 8.1%, using a poultry feed with a pH of 8.2 ± 1.0. Significant differences among inoculation levels for length, weight, survival and proximate composition were recorded ( p < 0.001). Significantly higher growth, survival rates and protein content were observed in larvae fed on P2‐inoculated feed ( p < 0.001). Findings of the present study demonstrate that exogenous Bacillus probiotic strain mixtures not only enhance larval growth but also survival rates and nutrient accumulation, thereby increasing overall production.
