Research of the physiological traits of a long-distance migratory insect, the common cutworm Spodoptera litura, in relation to flight and reproduction, was focused on triacylglycerol (TG) levels and their fatty acid composition.
Tethered flight experiments demonstrated that three-day old male moths can fly more than 20 h. Among eight identified fatty acids of which the adult TG is composed, the ratios of the following unsaturated fatty acids, palmitoleic acid (C 16:1), oleic acid (C 18:1), linoleic acid (C 18:2) and linolenic acid (C 18:3), gradually declined with longer flight duration. On the other hand, the TG levels of non-flown males reared for ten days on only water, were the same as those of three-day old males after 12 hr of flight, but the ratios of these unsaturated fatty acids in TG's remained nearly unchanged. These results suggest that the unsaturated fatty acids in TG are mainly used as a flight energy source.
As ovarian development in females of this species occurs shortly after adult emergence, long-distance migratory capacity has been regarded as highly unlikely. In fact, ovarian development was completed within three days after adult emergence and females laid eggs thereafter. During this three day period TG increased in the ovary, accompanied by increasing ratios of unsaturated fatty acids in the TG's and the ovary eventually occupied most of the abdomen, in spite of a nearly constant level of TG in the abdomen and unchanged ratio of its unsaturated fatty acids. These facts support the transfer of TG from the fat body to the ovary, and further suggest that the mature females utilize the TG deposited in the ovaries as a flight energy source. Then if they migrate a long distance, they use residual TG after flight for egg production.
Factors were examined that could be responsible for the predominance of Coccinella septempunctata (C7) in most habitats of the Palaearctic and for its successful invasion of the Nearctic Region. C7 is euryphagous, but less polyphagous than Harmonia axyridis or Coleomegilla maculata in that it cannot develop or reproduce on non-aphid food. The intraguild status of C7 is intermediate. Although adult size is large, preimaginal stages are palatable to those of H. axyridis and Adalia bipunctata, whereas it is not an intraguild predator of these species. Although these traits appear to be neutral or negative, many aspects of population plasticity are advantageous for C7, often acting in concert with a bet-hedging strategy. Given its high mobility and eurytopy, the inhibition of oviposition in the presence of conspecific larval trails represents an adaptive advantage that favors increased egg dispersal and lowers the risk of offspring mortality due to cannibalism. The ability to temporarily suspend oviposition, combined with heterogenous voltinism and diapause tendencies, enable a portion of C7 populations to feed and reproduce on unpredictably occurring aphid populations. An absence of reproductive diapause in males and pre-hibernation mating are other significant adaptations, along with the tendency to produce offspring in excess of the carrying capacity of local food resources. We suggest that one explanation for the broad geographic success of C7 resides in an ecological plasticity that is based on both genetic and phenotypic polymorphisms.
The percentage of transnational marriages is quite low in Slovakia. This relates to the increasing mobility of domestic inhabitants abroad as well as to the arrival of foreigners in Slovakia during recent decades. The study is to explain the cultural and historical background of mixed marriages between Slovaks and foreigners, their family life and the integration in the Slovak environment, namely in the context of migration experience of the partners in these relationships. In the introduction, we characterize the transnational marriages using available statistical data. We will
investigate the integration processes on selected type of transnational marriages, in which the partner comes from Egypt, Algeria or Tunis. We will focus mainly on their communication strategies and employability in the labour market.