Insects

Many ant species play a relevant role in the successional patterns of insects colonizing human and animal corpses. Although feeding behavior in ants depends on the trophic preferences of each taxon, these insects are often reported in several studies as predators of eggs, larvae, and adults of necrophagous insects. Among ants, some species are known to cause damage on human and animal dermis, known as post-mortem skin artifacts. The extensive activity of worker ants on corpses may hinder forensic pathological investigations aimed at determining the cause and location of death, as well as the assessment of entomologists in estimating the minimum post-mortem interval. We report for the first time a case of skin lesions on a human corpse found in a suburban area of the city of Cosenza (Calabria, Southern Italy), caused by the ant Pheidole pallidula (Hymenoptera: Formicidae). During the autopsy, numerous individuals (major and minor workers) were observed feeding on the corpse, but no other insects were found on it. We discuss the appearance of skin artifacts caused by P. pallidula and provide an overview of the genus Pheidole in forensic entomology.

Insects rely on their olfactory systems for host finding, mate choice, and oviposition. These odor-guided behaviors are mediated by the peripheral chemosensory system. The solanaceous pests Phthorimaea operculella and Phthorimaea absoluta cause severe damage to solanaceous crops worldwide. In this study, we aimed to elucidate the olfactory molecular mechanisms of these two pests. We first screened and identified odorant-binding proteins (OBPs), chemosensory proteins (CSPs), and sensory neuron membrane proteins (SNMPs) from the genomes of P. operculella and P. absoluta. We then used RNA sequencing to characterize the tissue expression profiles of OBPs, CSPs, and SNMPs in P. operculella across developmental stages and adult chemosensory organs. From P. operculella, 47 OBPs, 26 CSPs, and 2 SNMPs were identified, and from P. absoluta, 39 OBPs, 24 CSPs, and 2 SNMPs were identified. RNA-seq-based expression profiling in P. operculella was used to resolve sex-biased deployment in antennae: DESeq2 analysis (|log₂FC| > 1, FDR < 0.05) identified 24 OBPs and four CSPs with significant sexual dimorphism, with 14 OBPs and four CSPs upregulated in female antennae (FAn) and 10 OBPs and one CSP, together with SNMP2, upregulated in male antennae (MAn). In reproductive tissues (FOv vs. MGe), three OBPs and one CSP were enriched in the female ovipositor (FOv), whereas six OBPs and five CSPs were enriched in male genitalia (MGe), and no SNMPs met the differential-expression threshold. These candidate genes provide molecular entry points for functional studies and for developing behavior-based, environmentally compatible management strategies for P. operculella and P. absoluta.

This study systematically compared the growth performance, nutrient composition, accumulation and speciation of selenium (Se), and in vitro bioaccessibility in yellow mealworm (Tenebrio molitor L.) larvae, which were reared on substrates supplemented with selenite (Se⁴⁺) and selenate (Se⁶⁺) at concentrations of 0, 5, 10, and 20 mg/kg over 28 days. The results showed that high Se concentrations (≥10 mg/kg) significantly reduced larval biomass, with Se⁶⁺ having a slightly stronger inhibitory effect than Se⁴⁺. The mealworms effectively accumulated Se in a dose- and form-dependent manner. Peak total Se concentrations were observed on day 14, after which there was a decline, suggesting the presence of potential elimination mechanisms, such as moulting. The bioaccumulation factors (BAFs) were all below 1, indicating its limited enrichment capacity for both Se⁴⁺ and Se⁶⁺. Nutrient composition was altered, with both Se forms stimulating crude protein and polysaccharide synthesis while inhibiting fat accumulation. Mineral content (Mg, Fe, Zn) was also modulated, with differences observed between the Se⁴⁺ and Se⁶⁺ treatments. Notably, mealworms exhibited a remarkable ability to biotransform inorganic Se into organic forms, with organic Se proportions exceeding 79% in all treatments. Selenate was more efficiently bio-converted, yielding a higher proportion of organic Se. In vitro gastrointestinal digestion revealed significantly higher Se bioaccessibility from Se⁶⁺-treated mealworms (up to 85.12%) than from Se⁴⁺-treated ones (up to 60.67%). Analysis of the bioaccessible fraction by Se speciation identified SeCys₂ as the dominant compound (>92% of the detected species), with much lower levels of SeMet. Trace amounts of unmetabolised Se⁶⁺ were only detected in the Se⁶⁺-exposed groups. These findings highlight T. molitor as an efficient bioreactor for producing bioaccessible, organically bound Se, primarily as SeCys₂, with Se⁶⁺ being the more favourable precursor for generating a high-quality, bioavailable source of Se for potential use in feed or food.