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The invasive sea slug Pleurobranchaea maculata has quickly spread along the southwestern Atlantic coast, expanding almost 1500 km from Mar del Plata (Buenos Aires) to Bahía Camarones (Chubut) in approximately six years. Certain features of its reproductive biology are of fundamental importance to understand its establishment and expansion. The present work provides a detailed description of the egg masses and intracapsular embryonic development of P. maculata in its non-native environment, described by means of field observations and microscopy (optical and scanning electron) techniques. Aquarium experiments to induce oviposition and to evaluate the effect of temperature on embryonic development were conducted to provide information on the potential invasion range of this species. The egg mass structure and peripheral distribution of embryos within it enable larger egg masses and, consequently, maximizing recruitment. Egg masses were observed in the field from July to January, increasing in number with rising daylight hours (maximum in summer). An experimental estimation showed that each individual can spawn at least a mean of five egg masses in an annual light cycle, representing, at least, more than half a million embryos per individual during a year. Significantly larger embryonic shell length and shorter embryonic developmental times were found at higher seawater temperatures. The limits of embryonic thermal tolerance during intracapsular development suggest P. maculata may continue extending its distribution range to the south. The comprehension of the reproductive strategies of the species in its invaded region favours the understanding of the invasive capacity of this potentially toxic sea slug.

This experiment was conducted in order to investigate the effect of the chelated form of trace elements in diet on the production traits, immunity, and blood parameters of Ross 308 broiler breeder chickens. Treatments included Treatment 1 (Negative control): Mn, Se, Cu, Fe and Zn provided as non-chelated form; Treatment 2 (Positive control): Mn, Se, Cu, Fe and Zn provided as chelated form; Treatment 3: Mn, Se, Cu, Fe and Zn provided as 50% chelated form and 50% non-chelated form; Treatment 4: Zn provided as chelated form; Treatment 5: Cu provided as chelated form; Treatment 6: Fe provided as chelated form; Treatment 7: Mn provided as chelated form; Treatment 8: Se provided as chelated form. The results showed that over the entire production period egg production and egg mass were affected by the experimental treatments (p < 0.05) and that the highest levels were observed in treatments 2 and 3. The chelated form of trace elements had a significant effect, increasing the number of settable eggs and decreasing the unsettable eggs over the entire production period (p < 0.05). Average egg weight over the entire period was not significantly changed (p > 0.05). The highest percentage of 2-yolk, thin shell, broken and small eggs was observed in 61st week of age significantly (p < 0.05). The experimental treatments had a significant effect on the immunity and the antibody titre against Newcastle disease showed a significant increase in treatments 2 and 8 (p < 0.05). The concentration of glucose, triglyceride, progesterone, AST and ALT were affected by the experimental treatments (p < 0.05). In conclusion, the use of a basic diet containing Zn, Fe, Cu, Se and Mn in the chelated form or the use of a basic diet containing mineral elements of Zn, Fe, Cu, Se and Mn with 50% non-chelated form and 50% in the chelated form improves the performance of production traits, immunity and blood parameters of Ross 308 broiler breeder chickens. Highlights Chelated form of trace elements in the diet led to improvement in productive traits, immune response and blood parameters compared to the mineral form Basic diet containing mineral elements of Zn, Fe, Cu, Se, and Mn, 50% in the non-chelated form and 50% in the chelated form led to a significant improvement in egg production, egg mass, egg weight and egg specific gravity Chelated form of trace elements in the diet led to a decrease in the number of abnormal eggs including double-yolk, thin shell, broken, deformed, and small eggs

This study aimed to evaluate the effectiveness of different LED lamp colors (red and white) on the productive performance and egg quality of light laying hens. A total of 144 birds of the commercial strain Hy-Line® W-36 aged 44 weeks were distributed in a completely randomized design with two treatments (red and white LEDs) and 12 replicates, totaling 24 experimental plots with six birds each. Treatment means were compared by the F Test (5% probability) on the statistical software SISVAR. This study found that laying hens under red LED lamps showed a trend of greater egg production bird-1 day-1 (%) (p = 0.084), average egg weight (g) (p = 0.0826), egg mass (p < 0.05), and shell thickness (mm) and height (mm) (p < 0.01), whereas birds under white LED light showed better yolk color (p < 0.05). It is concluded that red LED illumination increases egg production and quality in light laying hens.

The spatial distribution of Lycorma delicatula (White) egg masses on three species of trees were studied in Pennsylvania. Five tree-of-heaven, five black walnut, and one Siberian elm trees were felled in early spring 2019 to sample for egg masses. Each egg mass was marked for its cardinal direction, position in the tree, height above ground, and spread from the bole. A total of 214 egg masses were found on tree-of-heaven and black walnut, with 38.3, 29.4, 22.0, and 10.3% on the north, west, south, and east quadrant, respectively. No significant difference in cardinal direction was found for either species. Equal number of egg masses were found on branches and boles on tree-of-heaven. However, significantly more egg masses were found on branches (96.5%) compared to boles (3.5%) on black walnut. Egg masses were laid at 0.30–12.92 and 0.70–17.00 m above ground, with most on boles/higher branches and middle/lower branches for tree-of-heaven and black walnut, respectively. Significant effect of height above ground was found for black walnut, with more egg masses found at 4–6 m compared to 0–2, 12–14, and 14–16 m. Significant effect of spread from the bole was found for tree-of-heaven, with more egg masses found at 0–2 m compared to 2–4 and 4–6 m. The 24 egg masses on the Siberian elm were mostly found on east quadrant branches 0–2 m above ground and within 2 m from the bole. Variation in tree branching patterns and difference in egg mass distribution of other forest pests were discussed.

A nondestructive sampling method was developed for Lycorma delicatula egg masses based on fixed-radius plot (100 m2) in 2020. All trees >1.0 cm DBH (diameter at breast height, 1.37 m in height) on each plot were visually inspected from the ground 4 m from the tree with binoculars. Egg masses found on trees were separated into six within-tree positions (lower trunk, middle trunk, upper trunk, first branch, second branch, above second branch) and recorded by cardinal directions, whereas those laid on shrubs/vines and stones were recorded without such separation. In total, 146 trees were inventoried at 28 plots over seven study sites (four plots per site). Egg masses were found on 19 tree species plus summer grape (Vitis aestivalis) and stone. Of the 421 total egg masses recorded, 31.1% were on Norway maple (Acer platanoides), followed by tree-of-heaven (Ailanthus altissima; 14.7%), black birch (Betula lenta; 12.6%), tuliptree (Liriodendron tulipifera; 11.9%), and American beech (Fagus grandifolia; 10.2%). Egg mass density per tree was positively correlated with tree diameter, and egg mass density per plot was positively correlated with plot basal area. Egg mass density after conversion ranged from 600 to 3,930 eggs masses/ha with no significant difference among study sites. Cardinal direction had no effect; however, significantly more egg masses were found on the first branches and upper trunks than other within-tree positions. Overall, branches were better than trunks in predicting egg mass number for the tree. The role of distance and late season adult aggregation on oviposition substrate selection are discussed.

This laboratory study examined the stimuli involved in controlling egg hatching in the desert locust Schistocerca gregaria. We found that eggs that were kept in their egg pods hatched in synchrony, whereas those that were kept individually hatched over an extended period of time and took significantly longer to hatch. Synchronous hatching was also observed in pairs of eggs that were kept in contact with each other in the same plastic wells, but not in those that were kept individually in separate wells. This demonstrates that the eggs needed to be placed in contact with each other to achieve synchronous hatching and suggests that a hatching individual stimulates adjacent eggs to hatch via some unknown stimulus. Additional experiments suggested that neither auditory nor pheromonal stimuli were important in this process, but rather some sort of vibratory stimulus. This inference was supported by the results of another experiment, which demonstrated that when isolated eggs were vibrated with a vortex mixer, most of them hatched shortly after the stimulation. Our results suggest the possibility that direct mechanical stimulation caused by the first egg to hatch stimulates adjacent eggs to also hatch, thus producing synchronous hatching in the entire egg pod. However, the exact nature of this stimulus remains to be determined.

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), is one of the world's most destructive and costly pests. Its larvae can attack more than 80 crop species including corn. FAW control efforts that have been carried out by most of our farmers involve synthetic pesticides. The development of plant pesticides with essential oil (EO) base materials is becoming increasingly innovative through nanoemulsion technology. This study aimed to determine the effective concentration/dose of the compound EO nanoemulsion (CEoNE) formula against FAW egg mass. The research was carried out from August to December 2023. FAW egg masses were collected daily in the screen house and brought to the laboratory to count the number of eggs in one egg mass under a stereo microscope. Preliminary tests were conducted to determine whether the right dose affects egg mortality. The results of preliminary tests on the dose of CEoNE showed that at a concentration of 15 ml/L, the average percentage of mortality of FAW egg groups reached more than 60% for 1-, 2- and 3-d-old FAW egg masses. These test results revealed that the concentrations of the CEoNE formula that would be further tested for FAW egg mortality were 11, 12, 13, 14 and 15ml/L to determine the LC 50 . The results show that, compared with the other treatments, the dose of 13.6 ml/L CEoNE is more effective against 3-d-old egg masses, which indicates that CEoNE has an ovicidal effect on S. frugiperda.

Egg size is a useful metric for maternal investment, offspring quality, and contaminant studies. Yet these values and the egg shape coefficients required to estimate egg size are not available for many species, including White-faced-Ibis (Plegadis chihi). We provide egg morphometrics derived from 319 White-faced Ibis eggs sampled at Bear River Migratory Bird Refuge, Great Salt Lake, Utah, from 2010 to 2012. Measured egg length (mean ± SD) was 51.20 ± 1.99 mm, egg width was 36.08 ± 1.15 mm, and whole egg mass was 34.1 ± 3.3 g. Estimated whole egg volume was 34.63 ± 3.73 cm3 and estimated egg shape coefficients were 0.507 for Kv (whole egg and egg contents), 0.547 for Kw (whole egg), and 0.524 for Kw (egg contents only). In addition, we documented expected declines in egg mass over time due to incubation (–0.22 g/d) and desiccation during storage (–0.03 g/d), that should be accounted for prior to analyses that use egg mass of freshly laid eggs.

Chironomids are abundant insects in freshwater habitats. They undergo a complete metamorphosis of four life stages: eggs, larvae, and pupae in water, and a terrestrial adult stage. Chironomids are known to be pollution-tolerant, but little is known about their resistance mechanisms to toxic substances. Here we review current knowledge regarding the chironomid microbiome. Chironomids were found as natural reservoirs of Vibrio cholerae and Aeromonas spp. A stable bacterial community was found in the egg masses and the larvae when both culture-dependent and -independent methods were used. A large portion of the endogenous bacterial species was closely related to species known as toxicant degraders. Bioassays based on Koch's postulates demonstrated that the chironomid microbiome plays a role in protecting its host from toxic hexavalent chromium and lead. V. cholerae, a stable resident in chironomids, is present at low prevalence. It degrades the egg masses by secreting haemagglutinin/protease, prevents eggs from hatching, and exhibits host pathogen interactions with chironomids. However, the nutrients from the degraded egg masses may support the growth of the other microbiome members and consequently control V. cholerae numbers in the egg mass. V. cholerae, other chironomid endogenous bacteria, and their chironomid host exhibit complex mutualistic relationships.

The males of the giant water bug, Kirkaldya deyrolli, care for egg masses on the emergent vegetation above the water surface in aquatic environments. A previous study reported that attending males supply the eggs with water and guard them against mature females (infanticide) until hatching. That study additionally concluded that males staying on the egg mass for longer than necessary may be a counterstrategy against females considering infanticide. In the present study, laboratory experiments were performed to evaluate the effect of conspecific females on paternal care during the egg-attending period using “with-” and “without-female” treatments. The hatching rates of eggs guarded by males with or without the presence of females were not significantly different. However, the proportion of males on the egg mass was significantly higher when the females were present than when not. We conclude that male behavior may be a counterstrategy against infanticidal females, in which males avoid and reduce the risk of detection by climbing out of the water when females are present.