Restricted within-habitat movement and time-constrained egg laying of female Maculinea rebeli butterflies

Abstract

The movement of butterflies within habitat patches is usually assumed to be random, although few studies have shown this unambiguously. In the case of the highly specialized genus Maculinea, two contradictory hypotheses exist to explain the movement and distribution of imagos within patches: (1) due to the high spatial variance of survival rates among caterpillars, the "risk-spreading" hypothesis predicts that females will tend to make linear flight paths in order to maximize their net displacement and scatter the eggs as widely as possible; and (2) recent mark-release-recapture (MRR) data suggest that within-habitat displacement of some Maculinea species is constrained and that adults may establish home ranges. We tested both hypothesis by analysing the movement pattern of individuals. We also investigated whether egg laying is time constrained, which would enhance the trade-off between flying and egg laying. Thirty females of Maculinea rebeli (Lepidoptera: Lycaenidae) were tracked within a single population in Central Hungary. Their egg-laying behaviour and individual patterns of movement were recorded, and the latter were compared with random walk model predictions. The population was also sampled by MRR to estimate survival rates, and four non-mated, freshly eclosed females were dissected to assess their potential egg load. Net squared displacement of females was significantly lower than predicted by the random walk model and declined continuously after the 15th move. The ratio of net displacement and cumulative move length decreased with the number of moves, supporting the hypothesis that Maculinea butterflies establish home ranges. We found that low survival and a low rate of egg laying prevented females from laying their potential number of eggs within their lifespan. Time limitation increased the cost of movement, providing another possible explanation for the restricted movement of females.

Movements and flight morphology in the endangered Large Blue butterflies

“…Most distances were only a few tens of meters and, particularly at the largest of the investigated patches, were much shorter than the patch dimensions. This supports the hypothesis that Phengaris butterflies do not move freely within their habitat patches, instead tending to establish home ranges [24,25].…”

What keeps ‘living dead’ alive: demography of a small and isolated population of Maculinea (= Phengaris) alcon

“…Our results concerning both the recorded movement distances as well as the estimated home range size suggest that M. alcon adults move freely within the southern fragment of the site, constituting the core habitat patch, and they occasionally venture to more distant areas. At first glance, unconstrained movements within a habitat patch seem nothing peculiar, but in Maculinea this is not necessarily the case, because these butterflies have been found to establish restricted home ranges within their habitat patches (Hovestadt and Nowicki 2008;Kőrösi et al 2008). The fact that in Bokiny they are able to mix freely is a further feature enhancing individual mating chances, and thus population viability.…”

Assessing the spatial distribution of Tuta absoluta (Lepidoptera: Gelechiidae) eggs in open‐field tomato cultivation through geostatistical analysis

“…The main axis of anisotropy occurred in the direction of the tomato crop rows, whereas the secondary axis occurred across the tomato crop rows. This difference in range of the egg infestation may explained by the structural orientations of tomatoes, which serve as an obstacle to the dispersal of adult T. absoluta between rows . Furthermore, the wind speeds may be higher in the direction of the rows than between the rows, and may thus contribute to greater dispersion of the adults and, consequently, greater dispersion of eggs in the direction of the rows.…”