Entomologia Experimentalis et Applicata最新文献

The blister beetle Epicauta atomaria (Germar) (Coleoptera: Meloidae) is a phytophagous pest of various agricultural crops, especially in Amaranthaceae, Solanaceae, and Fabaceae. Currently, this insect is managed through the spraying of synthetic insecticides that cause serious human health and environmental damage. To reduce the use of synthetic insecticides, the integrated pest management (IPM) programs for other crop pests rely on the use of semiochemical compounds, such as pheromones, kairomones, and allomones, to manipulate the insects' behavior to prevent crop damage. However, studies on semiochemical compounds related to E. atomaria have never been carried out. For this reason, the aim of this study was to explore the chemical communication of E. atomaria. This includes the existence of (i) a sex and/or an aggregation pheromone, (ii) attractant volatile kairomones from host plants, and (iii) repellent volatile allomones from non-host plants. Tests were carried out using olfactometers and an experimental arena. First, olfactometer tests failed to show the existence of volatile sex and/or aggregation pheromones of these insects. Second, olfactometer and experimental arena tests failed to demonstrate attraction of E. atomaria via volatile kairomonal compounds from host plants (chard, bell pepper, and cock's-eggs). However, olfactometer tests showed that non-host plants of E. atomaria (thyme and lavender) emit allomonal volatile compounds with repellent activity. This work represents a first step toward the elucidation of the chemical ecology of E. atomaria and suggests that volatiles from non-host plants help shape the host preferences of these insects. Those volatiles could be used as a “push” component in a “push–pull” strategy against this pest.

The use of pathogens and other natural enemies to suppress pest populations is a key component of integrated pest management (IPM) strategies. As biocontrol agents may interact synergistically, additively, or antagonistically, it is crucial to assess their interactions for effective pest management. In this study, we investigated the effect of three entomopathogenic fungus (EPF) species—Beauveria bassiana (Bals.-Criv.) Vuill. CEP 091, Akanthomyces muscarius (Petch) Spatafora, Kepler & B. Shrestha CEP 182, and Cordyceps fumosorosea (Wize) Kepler, B. Shrestha & Spatafora CEP 315 (all Hypocreales)—on the survival, fecundity, and searching behavior of Orius insidiosus (Say) (Hemiptera: Anthocoridae). All three EPF species were found to be pathogenic to O. insidiosus, resulting in a significant decrease in survival compared with the control group. Fecundity remained unaffected by the fungal treatments. No effect of EPF on searching behavior of the predator was found. In relation to the searching behavior, individuals of 2 days post-infections remained in the food patch longer than individuals of 7 days post-infections, regardless of treatment. These findings provide valuable insights into the compatibility of EPF and O. insidiosus as combined biocontrol agents for managing whiteflies, aphids, and thrips. Understanding the interactions between EPF and predatory insects is crucial for developing IPM strategies that maximize pest control efficacy. Further studies should explore the long-term effects of EPF on O. insidiosus populations and their overall impact on pest management in agricultural systems.

Koinobiont parasitoids do not prevent host development immediately after the attack, hence the quality of their resource units may vary over time. Potential advantages exist, though less clear, of choosing a host of better initial nutritional quality. We studied the effect of host nutritional quality on Mallophora ruficauda Wiedemann (Diptera: Asilidae), a solitary, koinobiont ectoparasitoid that preferentially attacks larvae of Cyclocephala signaticollis Burmeister (Coleoptera: Scarabaeidae). In the field, lighter hosts were parasitized more often than heavier hosts, but sex did not explain parasitism patterns. Our experiments showed that parasitoid larvae did not differentially attack heavier or lighter hosts in either two- or four-choice selection experiments, but do show differential selection based on the size of the host. Experiments simulating a host patch showed that parasitoid larvae choose larger hosts, but at a finer scale, as the size of the hosts increased, larvae chose the smaller host in a dyad. These results suggest that M. ruficauda larvae may select hosts of higher nutritional quality (i.e., larger hosts) but that there is an upper limit where a trade-off between nutrient acquisition and survival (related to life expectancy or host defenses) may drive the larval decisions.

Termites (Isoptera) constitute a considerable fraction of the global animal biomass. Conventionally, termite dry biomass estimates (g) range between 1:3 and 1:6 of fresh biomass (g). But estimates are often based on a few species or coarse taxonomic resolution. In this study, we (1) calculated the fresh and dry mass of 15 widely distributed Neotropical termite species (three families) and (2) established the conversion ratio for dry mass, which is indispensable for biomass estimates. Workers and soldiers were sampled in their colonies and quickly weighed in the laboratory to obtain the fresh mass. Then, the individuals were placed in 80% alcohol for 5 days and weighed. Finally, the samples were dried at 60°C for 24 h and weighed again. Our results suggest an average ratio of 1:4.2 (dry-to-fresh mass), with a mean (±SE) conversion ratio of 0.24 ± 0.06, for estimating termite biomass at local, regional, and global scales. Moreover, our results demonstrate that values from termites preserved in alcohol could still be used to estimate biomass. Specifically, after insertion in alcohol, the termites lost 16.9%–56% of their water content, with an average of 26.5%. While this represents a source of bias in estimates using samples from biological collections, dry mass was significantly related to fresh mass ($��R_{\mathrm{adj}}^2�$ = 0.99; dry mass = 0.000055 + 0.22 × fresh mass), and to the mass of termites in alcohol ($��R_{\mathrm{adj}}^2�$ = 0.97; dry mass = 0.00014 + 0.26 × mass in alcohol). Applying our results to data from the literature indicates that global termite dry biomass ranges from 89 to 106 Mt.

Notonecta species (Hemiptera: Notonectidae) are generalist true predators with a strong impact on the size, structure, and richness of the aquatic communities, particularly on mosquito populations. Juvenile and adult backswimmers not only prey on mosquito larvae (consumptive effect) but their presence can also deter the oviposition of gravid mosquito females (non-consumptive effect). In this study, we selected a Western Palearctic backswimmer, Notonecta maculata Fabricius, as a predator and deterrent of the highly invasive and health-threatening Asian tiger mosquito, Aedes albopictus (Skuse) (Diptera: Culicidae). In central Italy, N. maculata is univoltine and overwinters in the adult stage. Females lay eggs from February to the end of May, and the first new adults will emerge in late June; the complete nymphal development requires 44.5 ± 3.1 days. The number of Ae. albopictus larvae preyed on by N. maculata during its growth increases while developing, going from 0.03 ± 0.02 larvae per day for first instar nymphs to 21.38 ± 2.90 for mature adults. Furthermore, the presence of a single N. maculata adult in a mosquito ovitrap is enough to discourage the Ae. albopictus oviposition for up to 5 days. Limiting mosquito populations and, consequently, the transmission of viruses and parasites should be our main goal. Therefore, the integrated management of Ae. albopictus by the use of insecticides and a predator (such as backswimmer juveniles and adults), even if only in specific situations, may be promising and feasible. A more in-depth knowledge of the biological cycle of N. maculata could help, consequently, to optimize its mass rearing.

The increasing restrictions on commercial toxic baits for controlling leaf-cutting ants have started a “gold rush” for alternative compounds, with agroecological extracts emerging as a promising option. Here, we tested for the first time the repellent effects of concentrated and diluted ant extracts and cow urine solution on laboratory colonies of Acromyrmex subterraneus (Forel) (Hymenoptera: Formicidae). The agroecological extracts preparation and application followed the information provided by peasants from the Movimento dos Trabalhadores Rurais Sem Terra in Brazil who carry out agroecology. First, we applied the agroecological extracts in the middle segment of the upper path of a foraging trail to determine whether they act as a chemical barrier. All agroecological extracts induced the deviation of the foraging flow from the upper path to the lateral path. However, only the concentrated ant extract reduced the leaf delivery rate. Also, we applied the agroecological extracts directly on the leaf disks and conducted a paired selection test. The proportion of transported leaf disks with concentrated ant extract and cow urine solution was lower than that of control disks. We suggest that the observed repellent efficacy of the concentrated ant extract may stem from its content of chemical compounds belonging to the same chemical group as the alarm pheromones found by other Acromyrmex species. As for the cow urine solution, we attribute its repellent effect to the presence of urea. Our findings highlight a significant repellent potential of the concentrated ant extract and cow urine solution for leaf-cutting ants, which may be applied both on foraging trails and on leaves of cultivated plants.

Many factors may affect the diversity and abundance of arthropods in their natural habitats including changes in temperature and humidity. Sometimes, large arthropods remain undetected in unsuspected habitats such as bird nests. Here, we explore the effects of an experiment modifying temperature and relative humidity inside the nest of a troglodyte bird species, the blue tit, Cyanistes caeruleus (L.) (Passeriformes: Paridae), on the abundance of dermestid beetles (Coleoptera: Dermestidae) inhabiting the nests. Ten taxa were identified, six at the species level and four—based on larval stages—at the genus level. Most of the dermestids found in the larval stage were nidicolous dermestids of the genus Anthrenus. Specimens of necrobiont dermestids (those that feed on carcasses in both the larval and adult stages) were found in lower numbers, and almost always in adult stages. The abundance of dermestid larvae found in blue tit nests where the temperature or the humidity were experimentally increased was significantly higher than in the control nests. In addition, adult necrobiont dermestids of genus Dermestes appeared more frequently in those nests where corpses of blue tit nestlings were found.

Recent, rapid arthropod declines have been tied to human activity. Yet, the propensity for human-produced noise to disturb the substrate-borne (vibratory) channel remains virtually untested despite arthropods' ubiquitous use of vibratory information. Characterizing the vibratory landscape at biologically relevant scales is an essential initial step. We aimed to measure vibratory noise across space and time to assess its potential overlap with the urban–rural range and season of a funnel-weaving spider, Agelenopsis pennsylvanica (C.L. Koch) (Araneae: Agelenidae), a common urban arthropod. We assessed 24-h ambient vibrations (hereafter vibratory “noise”) at 23 sites across urban–rural Lincoln, Nebraska (NE, USA), during the adult season of A. pennsylvanica (August–October). Vibratory noise (amplitude, Leq) varied by ~15 dB across sites overlapping with frequencies within A. pennsylvanica's sensitivity (20–1000 Hz). Urban vibratory noise was positively correlated with the principal component containing estimates of traffic-induced vibrations (e.g., traffic volume, road proximity, and impervious cover), whereas rural noise levels correlated with probable harvest times. Our findings indicate spatial variation in noise in urban areas and seasonal noise variability in rural areas. We also tested how A. pennsylvanica—collected from four distinct noise survey sites—use their vibratory microhabitat. We assessed daily spider position and dry silk mass within a microcosm that played loud and quiet vibrations (white noise differing by ~15 dB) in separate but connected chambers. Age affected the chamber choice (hereafter “microhabitat use”) of spiders collected from the loudest site, as younger adults associated with and used more silk in the loud chamber, but this effect decreased with age. As our data demonstrate that vibratory noise varies with A. pennsylvanica's microhabitat and season with a high potential for impacting behavior, we hypothesize that this environmental noise likely impacts other arthropods as well.

Because of the brief and cryptic nature of predatory behavior, sentinel prey has been widely adopted as an indirect way to identify predators and understand trophic interactions. However, sentinel prey presents only static visual cues, potentially biasing toward visually oriented predators while ignoring those that utilize other sensory cues for foraging. Despite this, the effectiveness of sentinel prey has rarely been tested. In this study, we focused on the weaver ant Oecophylla smaragdina Fabricius (Hymenoptera: Formicidae), a keystone predator widespread in the Asian and Australian tropics. As this species has large eyes and is known to visually navigate in its arboreal habitats, we hypothesized that it relies on visual cues to forage and that its predatory behavior will be captured by caterpillar-shaped sentinel prey. Ants were collected as colonies, and preference trials on baits were conducted using combinations of olfactory and static visual cues, including the caterpillar shape. Surprisingly, O. smaragdina showed little or no preference for baits in the absence of olfactory cues and did not differentiate the shapes of baits regardless of olfactory cues. Our results indicate that O. smaragdina is likely to make predatory decisions based primarily on olfactory cues, whereas visual cues might be used for other behaviors. Furthermore, O. smaragdina is likely to be left out by the predation studies using sentinel prey models, which is particularly alarming considering the dominant role of this species in the trophic interactions of tropical rainforests. Our study demonstrates that morphological characteristics, arboreal habitats, and visually oriented behavior do not necessarily suggest the use of static visual cues for predatory decisions. We suggest that sentinel prey models should not be used alone when the dominant predators are unlikely to use visual cues to make predatory decisions.

Florfenicol (FF) is a new antibiotic commonly used in sericulture. This study aimed to examine the effects of low (LC: 0.06 g/L), medium (MC: 0.12 g/L), and high (HC: 1.2 g/L) concentrations of FF on the midgut physiological functions of the silkworm, Bombyx mori (L.) (Lepidoptera: Bombycidae). The results showed that the body weight and the whole cocoon weight of silkworms decreased and the development duration of the fifth instar was prolonged in the HC group. The structure of intestinal microbiota of silkworm larvae was changed by high FF exposure. Specifically, the abundance of conditional pathogens (Curtobacterium, Sanguibater, etc.) was significantly increased, whereas the abundance of Pseudomonas and Pedobacter was decreased significantly. Additionally, the intestinal reactive oxygen species level at 72 h was significantly elevated, and the muscle layer had become loose, together with the appearance of gut goblet cell atrophy. We observed that the increase in Lactobacillus abundance led to a reduction in intestinal fluid pH, resulting in decreased α-amylase and protease activities, whereas lipase activity exhibited an elevation. The results demonstrated that the accumulation of peroxides induced by exposure to 1.2 g/L FF caused intestinal damage, and the decrease in pH resulting from alterations in microbial composition and structure affected digestive enzyme activity, collectively leading to physiological impairment of the silkworm midgut. These findings provide a valuable reference for the safe use of FF in sericulture.