Behavioral ecology of Myiopharus doryphorae and Myiopharus aberrans, tachinid parasitoids of the Colorado potato beetle.

The life history and behavioral ecology of Myiopharus doryphorae (Riley) and Myiopharus aberrans (Townsend), important parasitoids of the Colorado potato beetle (CPB) Leptinotarsa decemlineata (Say), were investigated through a series of field and laboratory studies. The recruitment-recruitment method of determining percentage parasitism was compared with traditional methods in assessing population dynamics of the CPB and Myiopharus. Over the three-year period of the study, percentage parasitism calculated from traditional foliage sampling showed an erratic pattern. Revised estimates employing the recruitment method revealed a consistent 30-50% mortality of CPB larvae due to parasitism even when the CPB prepupal population density reached 80 per square meter per generation, showing that Myiopharus spp. can cause high levels of mortality to CPB larvae at higher host densities than has been reported in most previous field studies. Field sampling demonstrated that M. doryphorae and M. aberrans overwinter as first-instar larvae within adult diapausing CPB and complete their development the following spring after the emergence of the parasitized beetles. Growth-chamber studies were conducted to quantify development of summer-generation M. doryphorae at different life stages. During the first four days after being larviposited, these M. doryphorae remain as first-instar larvae but grow an average of 0.45 $\pm$ 0.03 mm prior to the prepupal stage of their hosts, in which the parasitoids complete development. During this latter period, development rates of M. doryphorae were found to track closely those of the CPB itself when modeled as a nonlinear function of temperature assuming cessation of growth outside the approximate range of 4-34\sp\circC. The model appears to require additional adjustment at temperatures below 10\sp\circC. Laboratory studies showed that M. doryphorae do not discriminate between CPB larvae fed sublethal doses of B. thuringiensis and larvae not fed with B. thuringiensis. M. doryphorae appear more sensitive to CPB larval movement than to the presence or absence of B. thuringiensis. Through field studies a series of behaviors was identified and their frequency and duration were quantified for the two Myiopharus spp., which appeared not to vary their allocation of time in response to each other\u27s presence in the same field. A significant difference was found between the frequencies of larviposition by the two Myiopharus species across ranges of temperature and time of day. Behavioral studies led to the discovery that larvipositing M. doryphorae and M. aberrans females discriminate between parasitized and non-parasitized host larvae, rejecting the former on contact and failing to larviposit in them when other potential hosts are available. This discrimination breaks down to some extent late in the growing season when CPB larvae of appropriate stages are rare; breakdown of host discrimination is accompanied, however, by the defense of recently parasitized hosts by females of both Myiopharus species, and is followed by the switch of larvipositing M. aberrans from larval hosts to adult CPB which are more common at this time of year

A subsystem-independent generalization of entanglement

We introduce a generalization of entanglement based on the idea that entanglement is relative to a distinguished subspace of observables rather than a distinguished subsystem decomposition. A pure quantum state is entangled relative to such a subspace if its expectations are a proper mixture of those of other states. Many information-theoretic aspects of entanglement can be extended to the general setting, suggesting new ways of measuring and classifying entanglement in multipartite systems. By going beyond the distinguishable-subsystem framework, generalized entanglement also provides novel tools for probing quantum correlations in interacting many-body systems.Comment: 5 pages, 1 encapsulated color figure, REVTeX4 styl