Tyrophagus putrescentiae (Schrank) (Astigmata: Acaridae) as natural enemy for wood boring pest, Psiloptera fastuosa F. (Coleoptera: Buprestidae) in tropical tasar

In tasar silkworm culture the stem-boring jewel beetle Psiloptera fastuosa Fabr. (Buprestidae: Coleoptera) is considered as a major pest of tasar plant (Terminalia arjuna, Combretaceae) cultivation. The grubs of P. fastuosa often damage the Arjuna stem by causing dieback. Tyrophagus putrescentiae Schrank (Acari: Acaridae) infested buprestid eggs up to 15% and caused egg mortality up to 9%. The mite predation on the buprestid beetle is reported for the first time. The mite seeps the newly-laid egg-fluids causing the egg mortality suggesting that tasar plant stem-boring pest (P. fastuosa) can be partially controlled by the mite as a natural enemy.

Life cycle of the dung beetle Onthophagus cervus (Fabricius, 1798) (Coleoptera: Scarabaeidae: Scarabaeinae) in moist belts of south India

Biology, nesting behaviour, and the factors favouring the high abundance of prominent dung beetle species, Onthophagus cervus (Fabricius, 1798) in an open agricultural field in North Kerala were studied. Short life cycle with high fecundity, low egg mortality, shorter larval duration, shorter developmental period, short generation time, female-biased sex ratio, and longer survivability of females were recorded. Female-biased sex ratio in O. cervus indicates that mating competition takes place between male offsprings and the high cost of producing males led to their reduction. Broad categorization of Onthophagus species is provided based on the comparison of data of brood mass production, fecundity, duration of egg, larval, pupal, adult stages, adult mortality and life span of various Onthophagus species. Higher abundance of O. cervus in the region is attributed to traits that are characterize of r-selection such as high fecundity, small body size, low egg mortality, shorter larval duration, early onset of maturity, and shorter developmental period. Short generation time which enables attaining maturity earlier together with female biased sex ratio, longer duration of females favouring high egg production and shallow tunnels which enable easy and fast tunnelling process and development in thin soil top soil layer are the other factors that contributed to the higher abundance of O. cervus. Present study showed that geographic region wise knowledge on the life history traits of prominent dung beetles are necessary for interpretation of the exact mechanism behind their seasonality and abundance in specific regions and the generated data will be useful for the conservation of species in natural habitats.

“The Caring Crustacean”: An Overview of Crustacean Parental Care

Many crustacean species are known to provide parental care, with behaviors ranging from ventilating the eggs to providing food for young. This chapter provides an overview of parental care patterns across crustaceans, and then compares crustacean parental care to that of select other taxa (insects, fishes, frogs) that share important traits with crustaceans (exoskeleton, aquatic or amphibious lifestyle, respectively). The aim is to identify gaps in the understanding of the evolution of parental care in crustaceans. We show that nearly all crustaceans provide parental care for early embryos (eggs), while caring for advanced stages is rarer. The most common forms of care are simple behaviors (e.g. fanning and cleaning behaviors), while complex behaviors (e.g. feeding the young) evolved exclusively in groups that also care for longer. Caring is most frequently done by females, while biparental is rare, and exclusive paternal care is nonexistent. When compared across taxa, simple behaviors are also the most common forms of care, and reasons for the evolution of parental care have common themes. First, parental care enhances offspring survival. In crustaceans, early embryo/egg mortality is apparently high, which might have triggered the evolution of parental care in several crustacean taxa independently. Second, crustaceans that have large eggs and inhabit stable habitats tend to care for longer. Lastly, internal fertilization seems to prevent male crustaceans from caring by not allowing the males to access the eggs and to ensure paternity.

Diferentes desinfetantes sobre a contaminação e desempenho da incubação de ovos de avestruz

From the moment of laying, eggs come into contact with microorganisms that adhere to the shelland disinfection is the process that reduces contamination by preventing them from penetrating the shell and invading the egg's internal content, however, different active principles can result in effects several. The objective was to evaluate the efficiency of different active principles in the disinfection of ostrich eggs on contamination andthe productive indexes of incubation. 16 eggs were used, distributed in two disinfectant active ingredients (quaternary ammonia and formaldehyde) in a completely randomized design with 8 replications. Contamination of the eggshell was evaluated by microbiological analysis on the surface of the eggshell after disinfection. The productive indexes of the incubation were evaluated by means of the index of weight loss of the egg (%), mortality rate (%), embryology (%) and hatchability (%). There was no significant difference (p> 0.05) between the active ingredients used in terms of disinfection capacity and productive indexes of incubation. It is concluded that bothactive ingredients are efficient in the disinfection of eggs, ensuring the control of contamination on the surface of the egg shell during the storage and incubation processes, in addition to not affecting the parameters of the incubation.

Different Oviposition Strategies of Closely Related Damselfly Species as an Effective Defense against Parasitoids

Parasitoidism is one of the main causes of insect egg mortality. Parasitoids are often able to detect eggs using semiochemicals released from eggs and disturbed plants. In response, female insects adopt a wide variety of oviposition strategies to reduce the detectability of eggs and subsequent mortality. We evaluated the proportion of parasitized and undeveloped eggs of three common damselfly species from the family Lestidae, the most diverse group of European damselflies, in terms of oviposition strategies, notably clutch patterning and the ability to utilize oviposition substrates with different mechanical properties. We assumed that higher costs associated with some oviposition strategies will be balanced by lower egg mortality. We found that the ability of Chalcolestes viridis to oviposit into very stiff substrates brings benefit in the form of a significantly lower rate of parasitoidism and lower proportion of undeveloped eggs. The fundamentally different phenology of Sympecma fusca and/or their ability to utilize dead plants as oviposition substrate resulted in eggs that were completely free of parasitoids. Our results indicated that ovipositing into substrates that are unsuitable for most damselfly species significantly reduces egg mortality. Notably, none of these oviposition strategies would work unless combined with other adaptations, such as prolonging the duration of the prolarval life stage or the ability to oviposit into stiff tissue.

A stage-based estimator of daily egg production

Snapper (Chrysophrys auratus) in South Australia spawn over a wide range of daily times and hatch in ∼1.5 d. Traditional estimates of daily egg production (i) divide sampled eggs into daily age cohorts, e.g. days 1 and 2, (ii) compute cohort ages by assuming that all spawning occurs at a fixed daily peak hour, and (iii) link the estimation of spawning egg density with egg mortality rate by regressing cohort egg densities against cohort age. We propose a method for estimating daily egg production, the number of eggs spawned per unit area per day (P0), without these assumptions. We use a range of estimates of snapper egg mortality rate obtained from prior studies to backcorrect for egg mortality to the age 0 spawning egg density for each stage of eggs individually rather than aggregating into daily cohorts. P0 is estimated as a mean of sample tow densities rather than as a regression intercept. This stage-based P0 estimator avoids errors associated with assuming a fixed daily spawning hour and classifying eggs into day 1 or 2. It requires no regressions of sampled daily cohort egg densities against age, which often provide imprecise estimates of mortality rates. Simulation testing showed 1–2% accuracy for this estimator of P0. The uncertainty of assuming egg mortality rates is moderated by the insensitivity of estimates of P0 to the input value of egg mortality rate.

Egg clutch dehydration induces early hatching in red-eyed treefrogs, Agalychnis callidryas

Terrestrial eggs have evolved repeatedly in tropical anurans exposing embryos to the new threat of dehydration. Red-eyed treefrogs, Agalychnis callidryas, lay eggs on plants over water. Maternally provided water allows shaded eggs in humid sites to develop to hatching without rainfall, but unshaded eggs and those in less humid sites can die from dehydration. Hatching responses of amphibian eggs to dry conditions are known from two lineages with independent origins of terrestrial eggs. Here, we experimentally tested for dehydration-induced early hatching in another lineage (Agalychnis callidryas, Phyllomedusidae), representing a third independent origin of terrestrial eggs. We also investigated how dehydration affected egg and clutch structure, and egg mortality. We collected clutches from a pond in Gamboa, Panama, and randomly allocated them to wet or dry treatments at age 1 day. Embryos hatched earlier from dry clutches than from wet clutches, accelerating hatching by ∼11%. Clutch thickness and egg diameter were affected by dehydration, diverging between treatments over time. Meanwhile, mortality in dry clutches was six-fold higher than in control clutches. With this study, early hatching responses to escape mortality from egg dehydration are now known from three anuran lineages with independent origins of terrestrial eggs, suggesting they may be widespread. Further studies are needed to understand how terrestrial amphibian eggs can respond to, or will be affected by, rapid changes in climate over the next decades.