Inflexible versus flexible: the influence of temperature and photoperiod on pre‐ and post‐eyespot development time in Libellulidae (Odonata)

Temperature and photoperiod are important environmental parameters for organisms. The present study tests the hypothesis that, during embryogenesis, temperature and photoperiod influence pre ‐ and post ‐ eyespot development time in dragonflies of the family Libellulidae differently. Eggs are used from eight species (five different genera, from Africa/Europe, and lentic/lotic habitat preferences). The eggs are reared under different constant or fluctuating temperature and light conditions. There are no general species‐specific degree‐days for pre ‐ or the post ‐ eyespot development in these species. In all study species, the variance within and between the treatments of the duration in days and the degree‐days of pre ‐ eyespot development is lower than that of post ‐ eyespot development. Pre ‐ eyespot development appears to be less flexible in its reaction to environmental influences. By contrast, post ‐ eyespot development appears to react more flexibly to environmental influences. All eight species show the same pattern. This indicates strongly that this flexibility is a general pattern in Libellulidae that might help the species within this family to cope successfully with variations in environmental conditions. Because eyespot development and katatrepsis occur close to each other, the above‐described pattern might also appear in other odonates and in other insect groups that exhibit katatrepsis. For all of them, it is essential for survival to match the time of hatching with adequate external temperature and photoperiodic conditions.     

Inhibition of the spoilage yeast Pichia occidentalis in a wheat germ diet for mass rearing of Drosophila suzukii

A wheat germ diet was initiated for the mass rearing of Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) and subsequent production of its parasitoid Trichopria drosophilae Perkins (Hymenoptera: Diapriidae). However, the main problem of the diet was the microbial contamination affecting the batches of good pupae production. Therefore, the concentration of four antimicrobials was optimized through the Taguchi orthogonal array for the inhibition of microbial contamination, identified as Pichia occidentalis (Kurtzman et al.) Kurtzman et al. The optimized Taguchi-selected-antimicrobials concentrations were 1.33 g l⁻¹ of potassium sorbate, 1.33 g l⁻¹ of propyl paraben, 1.33 g l⁻¹ of sodium propionate, and 0.16 g l⁻¹ of triclosan. When the antimicrobials were added to the diet, colony-forming units of P. occidentalis were inhibited by two orders of magnitude. Such inhibition means that the D. suzukii females produced 61.1 and 79.3% more pupae and adults, respectively, than the diet with no antimicrobials. These results increase the potential of the wheat germ diet as an artificial diet for mass rearing of D. suzukii and T. drosophilae.     

The costs of infant carrying in captive cotton-top tamarins

Marmosets and tamarins have a communal rearing system in which all group members help to care for the twin infants characteristic of this family of primates. Helpers are likely to incur time and energy costs by contributing to infant care. Predictions that cotton-top tamarin (Saguinus oedipus) helpers would change their behavior when carrying infants because of reduced mobility and/or a need for increased vigilance were tested in a captive colony. Tamarins carrying an infant spent significantly less time feeding, foraging, moving, or engaging in social activities such as grooming than they did when not carrying. Frequencies of scratching, autogrooming, and scent marking were significantly reduced in carriers, suggesting that their mobility was reduced. However, carriers were significantly less likely to be vigilant (measured by direction of gaze) than when not carrying. Further observations showed that carriers spent more time in concealed areas than they did when not carrying and were probably therefore adopting a cryptic strategy to reduce predation risks to themselves and to infants. These results demonstrate that tamarin helpers pay costs by carrying infants. Some possible compensating benefits are indicated.     

An electrified enclosure of 650 m2 designed for rearing baboons (Papio papio)

A system for an electrified enclosure designed for baboons is described. Live wires were alternated with grounded wires in order to increase the likelihood of electric shock if an animal tried to escape. A sinusoidal current of 50-Hz frequency, 650-V voltage, and 10 mA was used and proved to be quite efficient and not dangerous. In order to make the apparatus more reliable the electric main sources were connected to an automatic control system which monitored irregularities in the supply and switches to an emergency circuit if necessary.     

Assessment of flax and hemp fibres in terms of their impact on the growth performance and health status of weaned piglets

Weaning is a critical phase in intensive piglet production marked by the frequent occurrence of digestive disorders posing health and economic burden. To stave off such weaning-related problems, antibiotics and supplements containing high levels of ZnO are often used. In this study, we investigated whether natural fibres obtained from two plants known for their dietary fibre profile and antioxidant properties: flax (Linum usitatissimum L.) and hemp (Cannabis sativa L.), can serve as a health-promoting diet supplement. The study was conducted on a total of 191 Polish Large White piglets from 18 L, from their birth to 56 days of age. Piglets were divided by litters into six groups: W1.5, F1.5, H1.5, W2.0, F2.0, and H2.0. Groups W1.5, F1.5, and H1.5 received feed supplemented with 1.5% fibre from wood cellulose (W), flax (F), and hemp (H), respectively, while groups W2.0, F2.0, and H2.0 received feed with a higher 2.0% content of the same fibres. Flax and hemp fibres were characterised by a complex composition, antioxidant properties due to the presence of phenolic acids, and low risk of mycotoxin contamination. Flax fibre resulted in best weight gains and feed conversion ratio (P ≤ 0.05) of piglets, while hemp fibre had higher positive effect on antioxidant status (P ≤ 0.05) compared to the other two fibre additives. Neither flax nor hemp fibres had any adverse effect on the haematological and biochemical blood parameters. Piglets receiving a diet with 1.5% added fibre showed better growth performance, while diet supplementation with 2% fibre had a beneficial effect on the content of butyric acid in the small intestinal chyme (P ≤ 0.05). The results suggested that both flax and hemp fibres can be innovative feed additives for weaned piglets. However, further studies should be conducted in commercial farms, as the effects of dietary fibre could vary in more challenging environmental conditions.     

A simple rearing chamber for lotic insect larvae

An effective rearing chamber for aquatic insects can be made from inexpensive commercially available products. An angled air line is attached to a round 400 ml Rubbermaid® dish with a snap-on lid to create a circular flow with bubbles. The lid included with the dish can be modified to accept a tube with fine mesh screen at one end for capturing emerging adults. This chamber is a reliable and effective technique for studying larval behavior and obtaining adults for species identification.     

Insects in production – an introduction

Insects have been on the menu of humans for centuries, but only recently we have begun to mass produce them for human food and animal feed. This introduction first paints a synopsis of mass cultured insects and their application. The new insect production industry raises many interesting fundamental and applied questions about insect biology and fitness. The second part of the introduction to this special issue addresses the 13 articles dealing with the improvement of mass-rearing efforts for a range of insects. The various studies focus on the effects of diet and microorganisms on relevant life-history traits and economic value of the insects. They reflect the current rapid developments in the insect production industry.     

An in-depth study of the larval head skeleton and the external feeding structures related with the ingestion of food particles by the eristaline flower flies Eristalis tenax and Eristalinus aeneus

There is an important lack of knowledge regarding the mechanisms and morphology of the structures involved in the feeding process of the bee-mimicking eristaline flower fly species (Diptera: Syrphidae). In order to look more deeply into their larval feeding biology, a morphological study of the head skeleton and the external feeding structures of the three larval instars of Eristalis tenax (L.) and Eristalinus aeneus (Scopoli), important pollinators and bioindicators of water quality, was carried out, using scanning electron microscopy and confocal laser scanning microscopy. Additionally, an analysis of the ingested particle size was conducted, using various pollen grains and fungal spores. The main differences, found between the third instars of both species, consisted of the more restrictive mandibular lobes of E. tenax, which prevent the ingestion of bigger particles, and a wider filtering area in the cibarium of E. aeneus, which increases the number of particles that can be retained and ingested. Eristalinus aeneus is able to ingest bigger particles (80–100 μm) than E. tenax (70–80 μm). These results suggest that the structures involved in the feeding process of E. aeneus are less restrictive, thus increasing its survival chances when, under artificial rearing conditions, the same medium is used for both species. This study may contribute to the improvement in artificial rearing for future studies on pollination and decomposition.     

Volatile organic compound concentrations and their health risks in various workplace microenvironments

Abstract

Volatile organic compounds (VOCs) are some of the most important pollutants that have adverse effects on human health. In this study, simultaneous indoor and outdoor air samples were collected from four types of microenvironments (restaurants, photocopy centers, dry cleaners, and auto paint shops) in Kocaeli, Turkey in both winter and summer. Twenty-four VOCs were detected using gas chromatography and a flame ionization detector. The aim of the study was to determine the VOC concentrations in various workplaces and investigate associated health risks. Results show that the highest mean total VOC concentrations are in auto paint shops (14,066 µg/m³ in winter, 3441 µg/m³ in summer) followed by dry cleaners, restaurants, and photocopy centers. Total cancer risk was approximately 310 times greater than the acceptable limit in auto paint shops, 44 times greater in restaurants, 42 times greater in dry cleaners, and 17 times greater in photocopy centers. Total hazard quotients were also greater than the acceptable limit in all microenvironments.