Small Larvae Research Articles

The red colour in chinicuil (Comadia redtenbacheri (Hammerschmidt)) is due to rhodommatin pigment

Abstract In Mexico, Comadia redtenbacheri (Hammerschmidt) is called chinicuil or agave red worm which is highly appreciated since pre-Hispanic period and was considered a delicacy greatly accept by the Aztec. At present, chinicuil is highly valued not only for its culinary value but also as an ornamental in the mezcal industry, although it has not been possible to preserve its intense red colour. One reason for this is probably that the pigment responsible for the reddish coloration of the chinicuil has not yet been identified, making it difficult to find a possible alternative for its preservation. For this reason, the aim of this research was to elucidate the chemical structure of the pigment responsible for the reddish coloration of chinicuil in order to expand knowledge of its properties and offer alternatives for colour preservation.. According to the results of this study, the size is decisive for the colour of the larvae. The small larvae are white, while the large larvae are reddish in colour. The results of the colour characteristics of the larvae showed that the large larvae tend to have a reddish coloration, while a yellowness or white coloration is observed in the other larval sizes. The chromatographic UV-Vis profile of the pigment in the large larvae showed signals characteristic of the ommochromes, which was confirmed by the 1H NMR spectra, in which characteristic signals of the aromatic rings, glycosides, carboxyl and amine groups were detected. These results lead to the conclusion that the principal pigment that gives the chinicuil its red colour is rhodommatin.

Climate change and polar marine invertebrates: life-history responses in a warmer, high CO2 world.

Polar marine invertebrates serve as bellwethers for species vulnerabilities in the face of changing climate at high latitudes of the Earth. Ocean acidification, warming/heatwaves, freshening, sea ice retreat and productivity change are challenges for polar species. Adaptations to life in cold water with intensely seasonal productivity has shaped species traits at both poles. Polar species have life histories often characterised as K-strategist or K-selected (e.g. slow growth and development, larval hypometabolism) that make them sensitive to climate stress and altered seasonal productivity. Moderate warming results in faster development and can have positive effects on development, up to a limit. However, ocean acidification can retard development, impair skeletogenesis and result in smaller larvae. Given the fast pace of warming, data on the thermal tolerance of larvae from diverse species is urgently needed, as well as knowledge of adaptive responses to ocean acidification and changes to sea ice and productivity. Predicted productivity increase would benefit energy-limited reproduction and development, while sea ice loss negatively impacts species with reproduction that directly or indirectly depend on this habitat. It is critical to understand the interactive effects between warming, acidification and other stressors. Polar specialists cannot migrate, making them susceptible to competition and extinction from range-extending subpolar species. The borealisation and australisation of Arctic and Antarctic ecosystems, respectively, is underway as these regions become more hospitable for the larval and adult life-history stages of lower-latitude species. Differences in biogeography and pace of change point to different prospects for Arctic and Antarctic communities. In this Commentary, we hypothesise outcomes for polar species based on life history traits and sensitivity to climate change and suggest research avenues to test our predictions.

Bacillus thuringiensis Cry14A family proteins as novel anthelmintics against gastrointestinal nematode parasites.

Bacillus thuringiensis crystal (Cry) proteins have been expressed in commercial transgenic crops for nearly 30 years, providing safe and effective control of insect pests and significantly reducing the application of hazardous chemical pesticides. B. thuringiensis crystal proteins have also been shown to target parasitic nematodes, including plant parasitic nematodes. Recently, transgenic soybean crops expressing Cry14Ab have been shown to provide control against the soybean cyst nematode Heterodera glycines, marking the first time a crystal protein is being commercialized in transgenic crops for control of a nematode pest. However, apart from H. glycines and the free-living nematode, Caenorhabditis elegans, the breadth of nematode activity of Cry14Ab, e.g., against gastrointestinal parasitic nematodes (GINs), has not been reported. Here we study the efficacy of Cry14Ab against a wide range of gastrointestinal nematode parasites (GINs) in vitro and in vivo. We find that Cry14Ab is effective in vitro against the barber's pole worm Haemonchus contortus larvae, small strongyles cyathostomin larvae, the hookworm Ancylostoma ceylanicum adults, the roundworm Ascaris suum L4 larvae, and the whipworm Trichuris muris adults. In rodents infected with GIN parasites, Cry14Ab is effective as an in vivo anthelmintic against the hookworms A. ceylanicum and N. americanus, against the mouse parasite Heligmosomoides polygyrus bakeri, and against the roundworm A. suum. Cry14Ab also variably reduces the reproduction of the whipworm T. muris in vivo. Using optimized profile Markov Models, we looked for other putative anthelmintic Cry proteins and, within this list, identified a Bt crystal protein, GenBank accession no. MF893203, that we produced and demonstrated intoxicated GINs. This protein, with 90% amino acid identity to Cry14Ab, is active against C. elegans, A. ceylanicum adults, and A. suum L4 larvae in vitro. MF893203 was given the official designation of Cry14Ac. Cry14Ac is also an effective in vivo anthelmintic against A. ceylanicum hookworms in hamsters and intestinal A. suum in mice. Taken together, our results demonstrate that Cry14Ab and Cry14Ac have wide therapeutic utility against GINs.

A new species of the genus Notodoma Lacordaire, 1854 (Coleoptera, Histeridae, Exosternini) from Korea, with a revised key to species of the genus.

A new species of the genus Notodoma Lacordaire, 1854 (Coleoptera, Histeridae, Exosternini), Notodoma koreanum sp. nov., is described from Korea. Most of them recognized from various fungi colonies, feeding on small insect eggs or larvae, as well as fungi. We present the descriptions and images of diagnostic characters for Korean Notodoma species, including Notodoma fungorum Lewis, 1884. Additionally, a revised key to all seven species of the genus Notodoma worldwide, including the newly described species, is provided.

Development and assessment of Nirgundi-Chakramardha biopesticide against Diamondback Moth on Cabbage

Introduction: The global population is rapidly approaching 9.7 billion by 2050, with Africa and Asia playing significant roles in this growth. This surge necessitates increased crop production, highlighting the importance of effective pest control to ensure food security. India, facing an annual crop loss of about 30% due to pests and diseases, emphasizes the urgency of maintaining ecological balance in natural ecosystems. The diamond back moth (Plutella xylostella L.) poses a substantial threat to cruciferous plants globally, causing severe yield losses of 50–80% in infested cabbage. Addressing this challenge is crucial for minimizing crop losses and securing successful harvests. Our study aimed to analyze the emergence and abundance of small, medium, and large-sized larvae before and after applying treatments. Materials and Methods: A study with five treatments, including Nirgundi-chakramardha biopesticide and a control (Cypermethrin), was conducted. Each treatment was replicated four times, and the entire experiment was set up using a randomized block design. Results: After chemical application, all treatments displayed significant differences. The biopesticide in our study produced notable results within trial groups. Notably, the control group exhibited excellent results compared to the other treatments. Conclusion: The Nirgundi-chakramardha Biopesticide exhibited insecticidal activity against Diamondback moth pests, specifically targeting medium-sized larvae. Although not statistically significant compared to the control group, its efficacy in pest control, especially during the larval stage, indicates its potential as a viable pest management option. Further research and optimization could improve its effectiveness in combating Diamondback moth infestations.

The Effect of Larval Density on Pupation Rate and Time to Emergence from Pupation in $Tenebrio$ $molitor$ Linnaeus, 1758 (Coleoptera: Tenebrionidae) Reared on Two Different Feeds

In our research, the yellow mealworm, $Tenebrio$ $molitor$ L. was used. The effects of two different foods on the pupation rate and time to emergence from pupation of $T.$ $molitor$ at different larval densities were investigated. The experiments were carried out under continuous dark laboratory conditions with a temperature of 27±2ᵒC and a relative humidity of 60%±5%. Two different nutrient and four larval density groups were used in the study. The first nutrient composition consisted of dry yeast and wheat germ (150 gr in total, 1/2) The second nutrient composition consisted of whole wheat flour and corn flour (150 gr in total, 1/1). Insects were bred primarily on the tested nutrient media. Experimental sets were prepared at four different larval densities for both foods. The number of larvae in plastic containers was adjusted to 20, 60, 200 and 600. To ensure equality, all larvae were selected from small larvae. (between 50 mg-120 mg). In our study, pupation rates were high, especially in groups consisting of 20 and 60 larvae. The percentage of pupation decreased at 200 larval densities and sharply decreased at 600 larval densities in both diets. Especially the negative effects of the density are more obvious in the second food. The effects on intensity were more pronounced, especially in pupation of larvae, not in terms of pup time. As a result, it would be advantageous for the larvae density not to be above 200 in terms of getting more yield and increasing the reproduction rate from $T.$ $molitor$, which is demanded in large numbers as live feed. In conclusion, for the production of $T.$ $molitor$, which is commonly used as live feed, it is preferable to have a larval density below 200 in order to get a higher yield and better reproduction rates.

Age and calorific restriction impact immature black soldier fly (Diptera: Stratiomyidae) thermal tolerance and preference

Abstract Thermal tolerance and preference are traits commonly considered when mass-producing farmed animals as temperature impacts production. In this study, the impact of age and calorific restriction of immature black soldier fly, Hermetia illucens (L.) (Diptera: Stratiomyidae) on associated thermal tolerance and preference was examined. Both age (7-d-old for young larvae and 14-d-old for old larvae) and calorific restriction (led to size differentiation, small for calorific restriction and large for non-restriction) within a given stage influenced thermal tolerance (i.e. KR50) and thermal preference. Results indicate the interaction between age and calorific restriction was significant on both larval and prepupal thermal tolerance but not thermal preference. Median heat tolerance KR50 ranged from 46.4 °C (large, old prepupae) to 48.4 °C (large, young larvae). Median cold tolerance KR50 ranged from 21.6 °C (small, young larvae) to 32.1 °C (small, old larvae). Young larvae preferred median temperatures ∼3.0 °C greater than old larvae. Large larvae preferred median temperatures ∼2.0 °C lower than small larvae. Results from this study indicate ontogeny (i.e. stage of development) and calorific restriction have significant impacts on black soldier fly thermal tolerance and preference. Precise regulation of temperature in an industrial setting is necessary for optimal batch production of the black soldier fly (e.g. survival) and for colony maintenance (e.g. prepupae producing adults and potentially eggs). The same can be said with regards to maintaining consistent age and calorific restriction of immatures produced within each batch as variation in such traits impacts thermal tolerance and preference (e.g. survival to harvest for producing protein or adults for colony) as well. The methods and temperatures used in this study could serve as a foundation for developing standard operating procedures for regulating temperatures experienced by black soldier fly larvae industrially produced.

Growth–feeding linkage in small pelagic fish larvae in the Kii Channel, Japan

AbstractThe linkage between growth rate and feeding success has been shown to strengthen the effects of early growth rate on later growth rate in the early life history of fish. However, the growth–feeding linkage largely remains to be tested at the individual level within the same populations/cohorts. We examined the growth–feeding linkage for multiple populations/cohorts in Japanese anchovy Engraulis japonicus larvae and Pacific round herring Etrumeus micropus larvae, through otolith microstructure analysis, based on samples collected from the commercial fishery for larval fish in the Kii Channel, Japan. The three growth–feeding mechanisms, which are based on the respective potential advantages of larger somatic size, higher growth rate, and earlier morphological development for achieving feeding success, were tested to understand how growth rate relates to feeding success. The “somatic size” mechanism was supported for all of six samples for anchovy larvae and three of four samples for round herring larvae. The “growth rate” mechanism was supported for two of six samples for anchovy larvae and three of four samples for round herring larvae. The “morphological development” mechanism was supported for three of four samples for anchovy larvae and all of three samples for round herring larvae. Overall, the present analysis supported the growth–feeding linkage but revealed the dynamics of the growth–feeding mechanisms. All the mechanisms were shown to operate at least for certain populations/cohorts, but none of them were universally effective over all populations/cohorts across the two species. Understanding the dynamics of the growth–feeding mechanisms would provide precious hints for considering strategies of predicting recruitment dynamics.

BmC/EBPZ gene is essential for the larval growth and development of silkworm, Bombyx mori.

The genetic male sterile line (GMS) of the silkworm Bombyx mori is a recessive mutant that is naturally mutated from the wild-type 898WB strain. One of the major characteristics of the GMS mutant is its small larvae. Through positional cloning, candidate genes for the GMS mutant were located in a region approximately 800.5kb long on the 24th linkage group of the silkworm. One of the genes was Bombyx mori CCAAT/enhancer-binding protein zeta (BmC/EBPZ), which is a member of the basic region-leucine zipper transcription factor family. Compared with the wild-type 898WB strain, the GMS mutant features a 9bp insertion in the 3'end of open reading frame sequence of BmC/EBPZ gene. Moreover, the high expression level of the BmC/EBPZ gene in the testis suggests that the gene is involved in the regulation of reproduction-related genes. Using the CRISPR/Cas9-mediated knockout system, we found that the BmC/EBPZ knockout strains had the same phenotypes as the GMS mutant, that is, the larvae were small. However, the larvae of BmC/EBPZ knockout strains died during the development of the third instar. Therefore, the BmC/EBPZ gene was identified as the major gene responsible for GMS mutation.

Life cycle and seasonal regulation of Onychogomphus forcipatus unguiculatus in the Seybouse River, Algeria (Insecta: Odonata)

Understanding the seasonal regulation and life cycle patterns of Odonata is critical to identifying the factors that influence their voltinism. While the life history and seasonal regulation of Odonata, particularly gomphids, has been studied extensively, few studies have focused on North African gomphids. This study aims to contribute to the understanding of the life cycle of Onychogomphus forcipatus unguiculatus (Vander Linden, 1823), a western Mediterranean gomphid, on the Seybouse River in northeastern Algeria and discuss its seasonal regulation. Our results imply that a generation of O. f. unguiculatus requires two years to develop. The appearance of small (F-6) larvae in early spring can be attributed to the hatching of eggs in the previous year, followed by their overwintering in interstitial habitats. This abrupt appearance of small larvae is the result of their unique life history strategy of developing and surviving in specialized habitats during winter, then continuously growing and developing. The senior cohort overlaps with its junior counterpart, overwintering primarily in instars F-1, F-2, and, to a lesser extent, F-3, before beginning to emerge in late spring and early summer. By examining the voltinism and life cycle patterns of O. f. unguiculatus, this study contributes to our understanding of the reproductive strategies and population dynamics of this western Mediterranean gomphid, as well as of factors affecting the phenology and ecology of Odonata, particularly in North Africa, and in this manner contributes to overall efforts to protect and manage freshwater ecosystems in this region.

Does Size Matter? Small and Large Larvae of Pikeperch (Sander lucioperca) in a Comparative Gene Expression Analysis

Size differences are common in the aquaculture of fishes. In the larviculture of cannibalistic species such as pikeperch, they majorly influence mortality rates and consequently provoke losses in the aquaculture industry. With this study, we aim to reveal molecular differences between small and large pikeperch of the same age using a set of 20 genes associated with essential developmental processes. Hereby, we applied a general study design to early and late larval pikeperch before the onset of piscivory to explore the causes of growth differences in these developmental groups. The analysis of the expression levels showed developmental but not size-related differences in PGC1A, TGFB1, MYOD1, MRF4, and the collagens COL1A1 and COL1A2. Furthermore, increased head lengths were found in larger late larvae compared to their smaller conspecifics. While no uniquely size-related expression differences were found, the expression patterns of PGC1A in combination with TGFB1 as regulators of the citric acid cycle indicate a possible influence of mitochondrial energy metabolism. Furthermore, expression differences of MYOD1 and MRF4 point out possible temporal advantages of myogenetic processes in the larger late larval group and hypothesise growth advantages of the larger late larvae resulting from various influences, which provide a promising target for future research.

Tritiated thymidine induces developmental delay, oxidative stress and gene overexpression in developing zebrafish (Danio rerio)

Tritium is a betta emitter radionuclide. Being an isotope of hydrogen, it is easily transferred to different environmental compartments, and to human and non-human biota. Considering that tritium levels are expected to rise in the upcoming decades with the development of nuclear facilities producing tritium using fission processes, investigating the potential toxicity of tritium to human and non-human biota is necessary. Tritiated thymidine, an organic form of tritium, has been used in this study to assess its toxicity on fish embryo development. Zebrafish embryos (3.5 hpf; hours post fertilization) have been exposed to tritiated thymidine at three different activity concentrations (7.5; 40; 110 kBq/mL) for four days. These experiments highlighted that zebrafish development was affected by the exposure to organic tritium, with smaller larvae at 3 dpf after exposure to the two lowest dose rates (22 and 170 µGy/h), a delayed hatching after exposure to the two highest dose rates (170 and 470 µGy/h), an increase in the spontaneous tail movement (1 dpf) and a decrease in the heartbeat (3 dpf) after exposure to the highest dose rate. The results also highlighted an increase in ROS production in larvae exposed to the intermediate dose rate. A dysregulation of many genes, involved in apoptosis, DNA repair or oxidative stress, was also found after 1 day of exposure to the lowest tritium dose rate. Our results thus suggest that exposure to tritiated thymidine from a dose rate as low as 22 µGy/h can lead to sublethal effects, with an effect on the development, dysregulation of many genes and increase of the ROS production. This paper provides valuable information on toxic effects arising from the exposure of fish to an organic form of tritium, which was the main objective of this study.

Synthesis of larval lamprey responses to dewatering: State of the science, critical uncertainties, and management implications

AbstractObjectiveDewatering of fine sediments in rivers and streams can kill many thousands of larval lampreys (order Petromyzontiformes) that are burrowed in these habitats. The larval life stage for lampreys lasts 3–10 years, and because larvae often aggregate in large numbers, negative impacts from dewatering could potentially deplete local populations and affect multiple year‐classes. Larval lampreys have not traditionally been considered during instream projects, but recent efforts to increase awareness of lamprey habitats have resulted in guidance on dewatering approaches to limit impacts to lampreys. Salvage efforts to rescue and relocate lampreys aim to mitigate losses, but a lack of understanding of lamprey responses limits the optimization of dewatering and salvage procedures.MethodsWe summarize the state of the science for nine factors that influence larval lamprey (Entosphenus and Lampetra spp.) responses to dewatering, including burrowing depth, the prevalence and timing of emergence, movements, survival, shoreline slope, dewatering rate, light, and lamprey size.ResultResearch suggests that (1) shoreline slope influences movement capability, (2) hot and sunny conditions increase the risk of mortality, (3) salvage activities cause minimal direct mortality, and (4) smaller larvae are especially vulnerable to negative impacts from dewatering because they are more likely to emerge and are less capable of movement. Critical uncertainties associated with dewatering include cues that drive emergence, the influence of sediment composition and stratigraphy, vertical distribution of larvae in natural settings, use of the hyporheic zone, the scale of predation losses, and the effectiveness and impacts of salvage activities.ConclusionBalancing investments in salvage operations and lamprey exclusion efforts (e.g., screening) and developing field survey approaches to evaluate lamprey use of the hyporheic zone are identified management implications and research needs. Addressing the critical uncertainties discussed here and providing updated, science‐based guidance on dewatering and salvage practices are suggested management actions to support lamprey conservation.

Body-weight gains in Blaberus craniifer cockroaches and the intensity of their infection with gregarines and nematodes

Intestinal parasites are considered to be able to hinder growth of the host animals, reducing the extent of food metabolism, damaging the intestines’ integrity by filling it with products of their metabolism. However, a long co-evolution can mitigate the negative impact of a parasite on the host organism. To study how parasites – nematodes Cranifera cranifera (Chitwood, 1932) Kloss, 1960 (Oxyurida, Thelastomatidae) and gregarines Protomagalhaensia granulosae Peregrine, 1970 and Blabericola cubensis (Peregrine, 1970) Clopton, 2009 (Eugregarinorida, Blabericolidae) – afffect the growth rates of cockroaches, we performed an experiment on 200 larvae of Blaberus craniifer Burmeister, 1838 (Blattodea, Blaberidae), varying in weight and age. We monitored changes in their body weight, intensity of food consumption, and after the experiment we counted gregarines in the midgut and nematodes in the hindgut. As a result, we found that 100% of the cockroaches were infected with two species of gregarines and one species of nematodes. The intestines of small cockroach larvae (weighing 300–400 mg) contained 16–18 specimens of gregarines on average. Large larvae had a weak tendency towards increase in the intensity of gregarine infestation. Similarly, there occurred changes in the intensity of nematode invasion: young larvae were infected on average by 8–10 specimens of nematodes and large larvae had an average of 12–14 nematodes. At the level of tendency, nematodes were observed to enhance the cockroaches’ growth rates following increase in intensity of the parasitic infection. We found that the two groups of parasites had no effect on one another: the number of gregarines had no effect on the number of specimens of nematodes and vice-versa, the number of nematodes had no effect on the number of gregarine specimens. Perhaps, this is related to different localizations of the parasites: gregarines for most of their life feed in the small intestine, while nematodes feed in the large intestine. Therefore, growth rates of the cockroaches in our experiment have not changed due to the parasites. This indicates minimization of negative effects of gregarines in the midgut and nematodes in the hindgut on the host’s life cycle, developed over long co-evolution.

Vacuum extraction: an effective larval sampling method for spotted-wing drosophila in small fruit crops.

Detecting and sampling the pest for pest management, either through enumerating their life stages or by quantifying the crop damage, is the cornerstone in deploying integrated pest management. Currently, for spotted-wing drosophila, Drosophila suzukii Matsumura, larval extraction from the fruit samples involves immersing the fruits in hot water, salt, or sugar solution. We are introducing a novel, fast, and effective larval sampling technique where D. suzukii larvae can be extracted from infested fruits by subjecting the fruit samples to vacuum pressure. We optimized the vacuum pressure and vacuum duration for larval extraction from blueberries by testing a range of vacuum pressures and durations. A vacuum pressure of -98 kPa for 60 min resulted in the maximum larval recovery of the small, medium, and large larvae from blueberries. A 30-min incubation at -98 kPa also yielded similar results. Larval extraction at -98 kPa for 60 min on average recovered 61, 70, and 83% of larvae from 2, 4, and 6-day incubated fruit samples, respectively. The fruit sample size (37, 149, and 298 g) did not affect the larval extraction efficacy. Additionally, comparing larval extraction efficacy at -98 kPa with the salt and sugar extraction, incubated for 10, 30, and 60 min, suggests that vacuum extraction is comparable to or more efficient than the salt and sugar methods in extracting larvae from the infested blueberries. Overall, our results indicate that vacuum sampling is a promising method for detecting D. suzukii larval infestation in small fruit crops.

Spatial Distribution of Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae) on Corn Crops in Durango, Mexico

Accurately determining the spatial distribution of an insect is crucial for making effective decisions and efficiently controlling their populations. This study aimed to determine the population distribution of Spodoptera frugiperda (J. E. Smith 1797) (Lepidoptera: Noctuidae) larvae in corn plots near the City of Durango, Mexico. A total of 30 corn-cultivated plots were sampled. In each plot, 5 points were selected (5 of coins method), where 10 consecutive corn plants in these phenological stages V4 to V10 were checked for the presence of larvae and recorded. Statistical analysis was conducted using Scattering Indices 2/χ2 and the Chi-square test (χ2). The results indicated that infestation was slightly higher during stage V6 than in V4 and V8. The population of S. frugiperda had a negative, aggregate, or binomial distribution only in stage V4 (corresponding to small larvae), while in other phenological stages, the distribution was random.

Efficacy and sorption of sulfur dioxide as a fumigant for control of navel orangeworm (Amyelois transitella) on stored pistachios

Sulfur dioxide (SO2) fumigation was evaluated for postharvest control of navel orangeworm (NOW), Amyelois transitella, on stored pistachios in a laboratory study. Sorption of SO2 on pistachios were measured at 5, 15, and 25 °C. Because of rapid sorption of SO2 on pistachios after SO2 injection, 3 h short fumigations were used to determine effective treatments against NOW eggs, larvae, and pupae. SO2 fumigation was effective against all of the life stages tested. However, large larvae in infested pistachios were most tolerant and eggs were most susceptible to SO2 fumigation. Smaller larvae were more susceptible to SO2 fumigation than larger larvae. Complete controls of eggs, larvae, and pupae were achieved in 3 h fumigations with 0.2, 2.0, and 1.0% SO2, respectively. Large SO2 fumigation trials each with 4.5 kg pistachios were conducted in a 19.8L chamber and complete control of 6th instar larvae were achieved in 3 h fumigation with about 1.6–1.8% SO2 at ambient temperatures of 18–21 °C. The results showed that SO2 fumigation has potential to control NOW on stored pistachios as well as to control other postharvest pests on stored products.

A novel automated method for the simultaneous detection of breathing frequency and amplitude in zebrafish (Danio rerio) embryos and larvae

Stress responses of fish to disruption of oxygen homeostasis include adjusted oxygen consumption rate (MO2) as well as the hyperventilation consisting of changes in breathing frequency (fv) and amplitude (fampl). However, studying the HVR in very small organisms such as zebrafish (Danio rerio) embryos and larvae is challenging, and breathing movements (i.e., fv) are usually manually counted, which is time- and human resource-intense, error-prone and does not provide information on the amplitude of breathing movements of the response, the breathing amplitude (fampl). Hence, in the present study, a new automated method was developed to simultaneously measure fv and fampl in small zebrafish embryos and larvae with the computer software DanioScope™. To compare HVR strategies at different life-stages of zebrafish and the physiologically linked MO2, hatched 4 d old embryos and early gill-breathing 12 d old larvae were treated with the HVR-inducing neurotoxic compound lindane (γ-hexachlorocyclohexane; γ-HCH) as a model substance. Comparison of manually counted fv with fv data measured by DanioScope™ at both life-stages showed high to moderate agreement between the two methods with respect to fv in control fish and in fish treated with lower lindane concentrations (3 - 18% deviation at 25 µg/L γ-HCH). With increasing lindane concentrations (100 and 400 µg/L γ-HCH), however, manual counts showed an average underestimation of fv by up to 30%, mainly due to very fast, rapidly successive, and indistinct movements of the fish, which cannot be properly detected by manual counts. Automated measurement thus proved significantly more sensitive, although several pre- and post-processing steps are needed. The improved automated detection of fv and the first reliable estimation of fampl in small fish embryos and larvae, as well as the inclusion of MO2, may provide new insights into different respiratory strategies and may, thus, represent a tool to lower the detection limit for reactions of different life-stages of fish to environmental stressors. In the present study, this became evident, as early gill-breathing 12 d old zebrafish larvae showed symptoms of respiratory failure (i.e., increase in fv, fampl and MO2, followed by subsequent lethargy) after exposure to lindane, whereas skin-breathing in 4 d old embryos proved mainly insensitive to the paralytic effects of lindane.

Identity of the insect larva described by Zippel et al. (2022) in the mid–Cretaceous Burmese (Kachin) amber (Hymenoptera, Tenthredinoidea, Blasticotomidae = Xyelotomidae, syn. nov.)

The fossil in consideration, a small insect larva some 4 mm long, has been described, illustrated and left unnamed by Zippel et al. (2022) as a larva of the beetle family Mordellidae. The same year it was re-identified, unnamed as yet, as a sawfly larva of the family Pamphiliidae (Batelka & Engel, 2022). In our opinion, re-interpretation of the fossil by the latter authors was only partially correct. It demonstrates diagnostic characters of a sawfly larva, but the family attribution of the larva to Pamphiliidae is questionable: in our opinion it is most similar to larval Blasticotomidae (Tenthredinoidea).

Predation efficiency of the carnivorous aquatic plant Utricularia australis against Asian tiger mosquito Aedes albopictus larvae: Implications for biological control

The Asian tiger mosquito, Aedes albopictus, one of the world’s worst invasive animal species and competent vector of many arboviruses, poses a serious threat to human health. An effective and environmentally friendly control strategy is required to mitigate the negative impacts of this pest. The aquatic carnivorous plants of the Utricularia genus, known as bladderworts, feed on invertebrates using their modified leaves as traps (bladders) and could be considered for biological control. The southern bladderwort, U. australis, was used in a no-choice experiment to test its predation ability against Ae. albopictus larvae. Larvae were divided in two size groups: 1st–2nd and 3rd–4th larval instars. Twenty Ae. albopictus larvae were placed inside 1 l plastic cups with a 30 cm long segment of the plant and left for a 7-day period. Twelve segments of U. australis were used, six for each larval size group, counting the number of bladders of each segment at the beginning of the experiment. The 7-day process was repeated five times for each segment/cup over a two-month period. The number of captured larvae and emerged adults was recorded daily. A total of 84 captured larvae were chosen to measure larval length, percentage of larval body trapped within the bladder, bladder perimeter and bladder area, in order to evaluate the ability of the bladders in capturing larvae, by complete or partial suction of the body, depending on the relative sizes of larvae and bladders. Results indicated that U. australis is an effective predator of Ae. albopictus larvae, with a higher efficiency against the 1st–2nd instar group (72%) compared to the 3rd–4th group (39%). The number of captured larvae depended on the number of bladders on each segment and instar group. The percentage of trapped larval body depended on the relationship between bladder size and larval length. Although the bladders effectively captured small larvae by complete suction of the body, they also killed 3rd–4th instar larvae by trapping a small portion of the body within the lumen. The plant segments continuously captured mosquito larvae, with an efficiency that did not decrease during the 2-month period. The use of U. australis as a biocontrol agent against Ae. albopictus larvae could be favoured by its ecological plasticity, broad distribution, its ability to thrive in small containers and the good overlap of the two species regarding phenology and habitat preferences.