Physiological Entomology最新文献

Insects' defences can be directed at both live and inactivated pathogens. Recognition of pathogen-associated structures leads to modulation of innate immune responses and oxidative stress in the host. The article presents results of experiments showing that inactivated vegetative cells of Bacillus thuringiensis, B. subtilis and B. cereus can modulate immune responses in Galleria mellonella in the absence of damage to the tissues of the midgut. In the first hours after feeding on Bacillus spp., an increase in the number of immunocompetent haemocytes was observed. Phenoloxidase activity in the haemolymph of wax moth larvae was inhibited, which is confirmed by the suppression of the production of reactive oxygen species (ROS) in haemolymph. In addition, it was found that the antioxidant response to the bacterial inoculation in the midgut and haemolymph is different. Probably, the local antioxidant defence system is configured in such a way that the level of (ROS) increases rapidly to perform useful biological functions and decreases just as quickly, minimising oxidative damage.

Lateralization, defined as the asymmetric organization of brain functions, is a widely recognized phenomenon observed in an increasing number of insect species. However, knowledge remains limited for Ostrinia furnacalis (Guenée), particularly regarding population-level courtship lateralization on maize plants in greenhouse environments. This study investigates the lateralized mating behaviours of O. furnacalis on maize plants in controlled greenhouse conditions. Our findings reveal distinct differences in two population-level lateralized mating behaviours (left-biased and right-biased approaches, and 180° turnings), demonstrating for the first time the influence of the host plant environment. Male moths consistently exhibited a right-biased approach and left-biased 180° turning behaviour towards the female during copulation on maize plant leaves, which was associated with a reduced number of mating attempts. In response, female moths on maize leaves exhibited decreased rejection rates and increased receptivity to right-sided approaches and left-biased 180° turnings for intromissive copulation. Males performing ultrasonic courtship songs with left-biased 180° turning, reduced female rejections and lower courtship aggression achieved significantly higher mating success on maize plant leaves than those with right-biased 180° turnings for intromissive copulation. These findings provide the first empirical evidence of host plant-mediated lateralized courtship behaviours in O. furnacalis under greenhouse conditions. They offer novel perspective into the adaptive value of behavioural lateralization and highlight its relevance in naturalistic settings. This work advances insect behavioural ecology and has potential implications for developing behaviour-based pest control strategies.

Recycling aluminium, which is widely utilized in industries such as packaging, poses a significant challenge in selecting the most efficient method that retains its properties while minimizing environmental impact. This study investigates the potential adverse effects of aluminium oxide nanoparticles (Al₂O₃ NPs) synthesized from disposable aluminium foil waste using two different recycling methods: conventional grinding (CG) and ball milling (BM). This study employs Drosophila melanogaster as a well-established in vivo model organism to determine which recycling technique yields nanoparticles (NPs) that are less harmful to non-targets. To assess this, a relevant concentration of each Al₂O₃ NPs formulation were added into the food medium. Seven days post feeding, alterations of adult’s midgut were analyzed at physiological and ultrastructure levels. The results showed that Al₂O₃ NPs had significant effects on digestive enzymes, regardless of how they are synthesized. In contrast to chitinase and protease, the activities of digestive enzymes such as lipase, phospholipase A₂, and carboxypeptidase were significantly higher in flies exposed to Al₂O₃ NPs synthesized by BM than those in fed on control food media or those supplemented with Al₂O₃ NPs synthesized by CG. Histological and ultrastructural analyses revealed that both formulations of Al₂O₃ NPs negatively impacted the midgut cells. However, the harmful effects were more pronounced in NPs synthesized by the BM method compared to those produced using the CG method. Where flies fed NPs synthesized by the BM method had indistinct peritrophic membranes, disrupted microvilli, and columnar and goblet cells with numerous vacuoles. Collectively, while the findings confirm the toxicity of Al₂O₃ NPs to Drosophila, the synthesis method used to process aluminum and convert it into nanoparticle form plays a significant role in determining its potential hazards and should be carefully considered.

Adults of some Triatomine species, the vectors of Chagas disease, release alarm pheromones when mechanically disturbed. In this study, we investigated the behavioural responses of male and female Triatoma pallidipennis (Stål, 1872) exposed to volatile compounds released by mechanically disturbed conspecifics. We hypothesised that there are differences between the sexes in terms of the presence and quantity of alarm compounds, as well as in the way that T. pallidipennis responds to alarm volatiles emitted by conspecifics. We videotaped insect responses to identify the behavioural acts of both sexes in response to volatiles emitted by disturbed adults. In addition, we identified the compounds emitted by both sexes when the insects were disturbed and evaluated their behavioural responses to isobutyric and propanoic acids, and electrophysiological responses to isobutyric acid. We found that both sexes of T. pallidipennis exhibited four behavioural acts: raising the head, antennae and thorax; rubbing the proboscis with the forelegs; running in an agitated manner; and walking away from the odour source. We also observed that, in the presence of volatile compounds from mechanically disturbed insects, females moved farther away from the odour source than males. We identified 18 compounds in females and 15 in males. The main components were isobutyric acid and propanoic acid, as well as aldehydes, esters and ketones. Behavioural responses to isobutyric acid and propanoic acid were similar to those evoked by volatiles emitted by insects that had been mechanically disturbed. These acids can be used as repellents to dislodge adults from their shelters, to monitor their presence or to develop push-pull systems.

Frankliniella occidentalis (Pergande) is a typical omnivorous insect with a wide range of hosts. It feeds on the leaves, pollen and nectar of plants, as well as the eggs of spider mites. Here, pine pollen (PP) and Tetranychus urticae Koch eggs were added on kidney bean leaves to examine the effects of additional nutrients on F. occidentalis. The differences in physiological parameters were measured after thrips fed on kidney bean leaves (KL), KL + pine pollen (KL + PP) and KL + T. urticae eggs (KL + TE). The results showed that the trehalose content, glycogen content and trehalase activity in thrips increased at most timepoints when they were fed on KL + PP and KL + TE, and the effects of KL + PP were greater than those of KL + TE. However, the different diets did not affect the glucose content. In addition, both KL + PP and KL + TE increased the vitellogenin (Vg) content in thrips at most timepoints. KL + PP had a greater effect on Vg expression than KL + TE. KL + PP and KL + TE also increased the juvenile hormone (JH) titre and the expression levels of JH signal transduction genes Krüppel-homologue 1 (kr-h1) and broad (br) in thrips at most timepoints; however, the different diets had no significant effect on the expression of the JH degradation gene Juvenile hormone epoxide hydrolase (JHEH) at most timepoints. All these results suggest that the carbohydrate, Vg and JH contents of F. occidentalis are correlated with different diets and that PP promotes the synthesis of these substances and the expression of related genes.

Galleria mellonella (Linnaeus, 1758) is a Lepidopteran pest insect infesting the honeycombs, and the last instar larva of the insect is also a valuable model organism for the evaluation of drug efficacy, pathogenicity of infectious agents and environmentally sound chemical insecticides. Levamisole is an anthelmintic drug that is used for the treatment of parasitic infections in animals. In this study, we investigated the oxidative and genotoxic effects of dietary levamisole on the haemolymph of G. mellonella last instars to evaluate levamisole as an alternative chemical for traditional insecticides. In this context, first instar larvae were reared up to the last instars on artificial diets containing levamisole (w/w) and a control diet without levamisole. Malondialdehyde (MDA) and protein carbonyl (PCO) contents, and the activity of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST) and glutathione peroxidase (GPx) were determined to evaluate oxidative stress in the haemolymph of G. mellonella last instars. Furthermore, a comet assay was performed on haemolymph for evaluating DNA damage levels. The dietary levamisole led to a significant decrease in MDA and PCO contents and antioxidant enzyme activities (SOD, CAT, GST and GPx) when compared to the control diet. However, dietary levamisole significantly increased tail moment, tail %DNA and tail length, which are strong indicators of DNA damage. We infer from these that levamisole induced DNA damage and crippled antioxidant enzymatic defence in correlation with gradually increasing dietary concentration. The study would also provide valuable insights into the multifunctional aspects of levamisole, including its use in pest management.

Defensive secretions produced by certain hemipterans are known to deter natural enemies and play a crucial role in reducing microbial infections. In this study, we investigated the protective mechanisms of the chinch bug Blissus pulchellus against entomopathogenic fungi and we explored the relationship between the major volatile compounds produced by B. pulchellus and their potential role in enhancing its resilience to disease. Both adults and nymphs exhibited low susceptibility to infection by various strains of Metarhizium anisopliae and Beauveria bassiana. The close and continuous contact of conidia with antimicrobial substances on the insect's integument significantly inhibited germination rates. Conidia washed from insects after 4 h of contact with their integument exhibited germination rates of less than 20% on culture media. Chemical analyses of body extracts from adults and nymphs revealed both qualitative and quantitative differences in their defensive compound profiles. Our findings suggest that the aldehydes are the primary compounds responsible for fungal inhibition, effectively protecting the insect from infection. Identifying fungal strains capable of overcoming the fungitoxic compounds produced by B. pulchellus is crucial for advancing mycopesticide development to manage chinch bug populations in pastures.

The present study assessed the feeding efficiency, macronutrient assimilation and larval development of the Parthenium beetle, Zygogramma bicolorata Pallister, a biocontrol agent for the invasive Parthenium weed, under varying temperature conditions. We hypothesized that deviations from the optimal temperature (~25°C) would impair larval feeding efficiency due to temperature-induced stress. Our results revealed that both larval consumption and growth rates declined at temperatures below (15°C, 20°C) and above (30°C) the optimal temperature (25°C). In contrast, food conversion efficiency improved as temperatures increased from 15 to 30°C. Protein assimilation by larvae decreased across the temperature range, while glucose assimilation increased. Triglyceride assimilation initially decreased from 15 to 20°C/25°C but increased from 20°C/25°C to 30°C. As temperatures increased from 15 to 30°C, both the body size and developmental durations of larvae decreased. These findings suggest that Z. bicolorata larvae adopt different survival strategies depending on temperature conditions. At suboptimal temperatures, larvae grow larger, assimilate more proteins and triglycerides, but consume and utilize food more slowly. Conversely, at supraoptimal temperatures, larvae exhibit reduced body size and food consumption rates, but their food utilization efficiency improves, leading to faster development. Therefore, both low and high temperatures could limit the biocontrol efficiency of Z. bicolorata larvae in the Indian subcontinent.

Cryptic colouration is a primary anti-predation strategy in herbivorous insects. Achieving crypsis often requires acquiring dietary carotenoids—tetraterpene pigments vital for plant colouration and photoprotection. Silicon (Si) accumulation in plants makes tissues tougher and less digestible for insects, but its effect on plant pigment levels remains unclear. It is also unknown whether feeding on silicified plants impairs insects' ability to sequester carotenoids and achieve crypsis. Using the model grass Brachypodium distachyon, we demonstrate that the cotton bollworm (Helicoverpa armigera) larvae exhibited stunted growth and reduced carotenoid sequestration, particularly lutein, into their haemolymph when feeding on Si-supplemented (+Si) plants. This reduction led to distinct body-colour morphs: larvae feeding on +Si plants developed brown colouration, contrasting sharply with the green leaves, whereas larvae feeding on Si-free (−Si) plants exhibited green cryptic colouration that blended seamlessly with the foliage. Plant leaves contained various carotenoids (neoxanthin, violaxanthin, β-carotene and lutein) and chlorophylls (a and b), but larvae only sequestered β-carotene and lutein into their haemolymph while excreting substantial amounts of pigments, regardless of plant Si status. Under insect-free conditions, +Si plants had lower carotenoid and chlorophyll contents than −Si plants. However, following insect herbivory, pigment levels in −Si and +Si plants equalised. Insect herbivory also increased Si accumulation in +Si plants. Our findings provide novel evidence that plant Si defences can disrupt cryptic colouration in insect herbivores by restricting carotenoid sequestration from host plant tissues. This disruption could increase insect visibility to predators, potentially elevating their risk of predation.

Circadian rhythms are essential for predicting environmental changes; however, little is known about factors regulating their ontogeny. Honey bee workers emerge from the pupae with no behavioural circadian rhythms but show strong rhythms later in their lives. Although a previous study showed that temperature in a colony plays a role in accelerating the ontogeny of circadian rhythms in young bees, it is still unknown whether there is an optimal temperature for the acceleration of rhythm ontogeny. In the present study, we examined the influence of four different temperatures (25, 29, 34 and 38°C) for 48 h and found that as the temperature increased, more bees exhibited circadian activity rhythms for a 5 days observation period. We also examined the influence of temperature and other factors in a colony by exposing bees to air inside the hive at 34°C (a temperature nearly identical to brood nest temperature) or 29°C. We found that regardless of whether bees were exposed to colony air, they maintained their temperature at 34°C during their first 48 h and were more likely to exhibit circadian activity rhythms during the 5-day observation period compared with bees maintained at 29°C. These results suggest that the temperature in a colony is the main factor influencing the ontogeny of circadian rhythms in young bees. We also demonstrate the presence of a critical period during which this temperature effect significantly accelerates rhythm ontogeny.