The evidence of temporary social parasitism by Polyrhachis lamellidens (Hymenoptera, Formicidae) in a Camponotus obscuripes colony (Hymenoptera, Formicidae)

Polyrhachis lamellidens is a temporary socially parasitic ant whose new queen utilizes other ant species in the early stages of colony foundation. Field observations and rearing experiments suggest that Camponotus japonicus is a host species of P. lamellidens. It is presumed that Camponotus obscuripes is also a host of P. lamellidens by rearing experiments and field observations; however, there are no records of P. lamellidens workers or brood coexisting in C. obscuripes colonies in field observations, and there is no clear evidence that C. obscuripes is a natural host of P. lamellidens. We conducted detailed field observations, behavioral tests, and rearing experiments to show that C. obscuripes is a host of temporary social parasites. We found colonies with P. lamellidens queens, workers, and larvae intermixed with C. obscuripes workers in the field. Behavioral tests showed that workers of both species in mixed colonies did not attack each other and maintained nestmate recognition ability, which suggests a collaborative nestmate relationship. Furthermore, a rearing experiment confirmed social parasitism by P. lamellidens among C. obscuripes by producing a mixed brood-producing colony. These are the first field and laboratory records of temporary social parasitism involving P. lamellidens and C. obscuripes.

Temperature dependency equation for chub mackerel (Scomber japonicus) identified by a laboratory rearing experiment and microscale analysis

In this study, juveniles of chub mackerel (Scomber japonicus) were reared from eggs in six different temperature treatments, and their otoliths were subjected to micromilling and microvolume stable oxygen isotope (δ18O) analysis. We determined the δ18O values of otoliths (δ18Ootolith) formed at mean temperatures of 16.3, 17.6, 18.3, 20.0, 24.0 and 26.5°C and identified a linear relationship between rearing water temperature (T, °C) and δ18Ootolith as follows: δ18Ootolith (VPDB) – δ18Owater (VSMOW) =–0.25 (±0.01)T+4.46 (±0.21) (R2=0.96, P<0.01), where VPDB is Vienna Peedee Belemnite, VSMOW is Vienna Standard Mean Ocean Water and the error values in parentheses are standard deviations. This species-specific temperature dependency equation for chub mackerel will enable accurate reconstruction of individual thermal histories and provide essential information for effective resource management.

Heterogony in Cycloneuroterus (Hymenoptera: Cynipidae: Cynipini) From Rearing Experiments and DNA Barcoding

Heterogony was confirmed in the cynipid genus Cycloneuroterus Melika and Tang in rearing experiments with DNA barcoding. These experiments involved Cycloneuroterus gilvus Tang and Melika, which was previously only described from the sexual generation adult. The first rearing experiment was conducted using unidentified asexual generation females collected from Quercus gilva Blume, and gall formation by the sexual generation offspring was confirmed on folded or unfolded young leaves of Q. gilva. The second experiment was conducted using sexual generation males and females reared from the leaf galls collected from Q. gilva, and gall formation by the asexual generation offspring was observed on leaves of Q. gilva. Based on the morphological features of the sexual generation adults and galls, this species was identified as C. gilvus. The species identity of wasp specimens of sexual and asexual generations used in the rearing experiments was cross-checked using DNA barcoding with the partial sequences of the cytochrome c oxidase subunit I (COI) region (658 bp). The asexual generation adult and gall of C. gilvus are described based on these results. The importance of ‘closing the life cycle,’ in this case a demonstration of heterogony, in oak gall wasps (Cynipini) is discussed.

Optimizing fish structure in angling ponds focusing on white fish

According to new amendments of laws, commercial fishing licenses of natural waters shall not be issued from the calendar year 2016 in Hungary. However, the most settlement of white fish to angler ponds originated from natural waters. Currently, there is no sufficient quantity of fish species belonging to this group available to fulfil the settlement commitments of fish farmers. The aim of this recent study is to develop a breeding and production technology that is suitable for settlement of large quantities of this fish species of appropriate length of (4–5 cm). The following methods are investigated: aquaculture cage system (pond-in-pond system), monoculture and mixed population with different ratio of white fish in fish structure. Due to the different environmental needs of different fish species, many parameters need to be investigated, for example: stocking density, feeding, oxygen level, monoculture or mixed populations, growth potential and mortality. A preliminary experiment was carried out following the artificial propagation of ide (Leuciscus idus) following a 21-day larval rearing experiment in which the effect of different stoking density was investigated for mortality and growth. On the basis of the expected results, the optimal conditions for the aquaculture cage system will be described, regarding to the white fish stock.

Effects of temperature on tissue–diet isotopic spacing of nitrogen and carbon in otolith organic matter

Reconstruction of the trophic position of a fish can be performed by analysing stable nitrogen and carbon isotopes in otolith protein. However, ambient temperature may affect the tissue–diet isotopic spacing of stable isotopes from diet to predator tissue and bias estimates of trophic position. To test this, otolith protein, heart and muscle tissue from a rearing experiment with juvenile cod held at different temperatures (4, 7, 10 and 14°C) were analysed. There was no significant effect of temperature on otolith δ15N, whereas muscle and heart exhibited a slight decrease in δ15N values with increasing temperature corresponding to maximum of 0.6‰ over the 10°C range. By contrast, the otolith protein δ13C values at 4 and 7°C were significantly higher than for 10 and 14°C, suggesting an approximate 1‰ increased tissue–diet enrichment at the lower temperatures. Temperature had no significant effect on muscle and heart δ13C values. Considering the annual mean variation in ocean temperatures, our results indicate that the trophic signals recorded in the otoliths will reflect changes in diet isotope values with little bias from the ambient temperature experienced by the fish.

The predictability of genomic changes underlying a recent host shift in Melissa blue butterflies

Despite accumulating evidence that evolution can be predictable, studies quantifying the predictability of evolution remain rare. Here, we measured the predictability of genome-wide evolutionary changes associated with a recent host shift in the Melissa blue butterfly (Lycaeides melissa). We asked whether and to what extent genome-wide patterns of evolutionary change in nature could be predicted (1) by comparisons among instances of repeated evolution, and (2) from SNP × performance associations in a lab experiment. We delineated the genetic loci (SNPs) most strongly associated with host use in twoL. melissalineages that colonized alfalfa. Whereas most SNPs were strongly associated with host use in none or one of these lineages, we detected a ~two-fold excess of SNPs associated with host use in both lineages. Similarly, we found that host-associated SNPs in nature could also be partially predicted from SNP × performance (survival and weight) associations in a lab rearing experiment. But the extent of overlap, and thus degree of predictability, was somewhat reduced. Although we were able to predict (to a modest extent) the SNPs most strongly associated with host use in nature (in terms of parallelism and from the experiment), we had little to no ability to predict the direction of evolutionary change during the colonization of alfalfa. Our results show that different aspects of evolution associated with recent adaptation can be more or less predictable, and highlight how stochastic and deterministic processes interact to drive patterns of genome-wide evolutionary change.

Bird droppings on chestnut leaves or sawfly larvae: DNA barcodes verify the occurrence of the archaic Megaxyela togashii (Hymenoptera, Xyelidae) in Hokkaido, Japan

We made a molecular phylogenetic analysis using mitochondrial cytochrome oxidase subunit 1 (COI) gene sequences for ten unidentified Megaxyela larvae from Hokkaido, Honshu and Shikoku, Japan, and 15 identified adults of four Megaxyela, one Macroxyela and three Xyela species. It revealed that all larvae belonged to M. togashii Shinohara, 1992, which showed rather large intraspecific genetic variability even among the individuals from the same population. This is the first distribution record of M. togashii from Hokkaido. Megaxyela togashii is a univoltine species with a very short larval feeding period, only nine days in one rearing experiment from egg to larval maturation. The larva is a solitary, external leaf-feeder on Juglans ailanthifolia, resting curled around the central leaf vein at the apex of a leaflet, and may resemble the excrement of birds. The prepupa overwinters in an earthen cell whose wall is made only of soil, neither parchment-like nor containing fiber. The mature larva is described and several life traits are discussed.