Insect eggs protected from high temperatures by limited homeothermy of plant leaves.

Virtually all aspects of insect biology are affected by body temperature, and many taxa have evolved sophisticated temperature-control mechanisms. All insects, however, begin life as eggs and lack the ability to thermoregulate. Eggs laid on leaves experience a thermal environment, and thus a body temperature, that is strongly influenced by the leaves themselves. Because plants can maintain leaf temperatures that differ from ambient, e.g. by evapotranspiration, plant hosts may protect eggs from extreme ambient temperatures. We examined the degree to which leaves buffer ambient thermal variation and whether that buffering benefits leaf-associated insect eggs. In particular, we: (1) measured temperature variation at oviposition sites in the field, (2) manipulated temperatures in the laboratory to determine the effect of different thermal conditions on embryo development time and survival, and (3) tested embryonic metabolic rates over increasing temperatures. Our results show that Datura wrightii leaves buffer Manduca sexta eggs from fatally high ambient temperatures in the southwestern USA. Moreover, small differences in temperature profiles among leaves can cause large variation in egg metabolic rate and development time. Specifically, large leaves were hotter than small leaves during the day, reaching temperatures that are stressfully high for eggs. This study provides the first mechanistic demonstration of how this type of leaf-constructed thermal refuge interacts with egg physiology.

Authentication of the 31 species of toxic and potent Chinese Materia Medica by light microscopy, Part 3: two species of T/PCMM from flowers and their common adulterants.

Toxic and potent Chinese Materia Medica (T/PCMM) has become a hot and sensitive topic as more and more people around the world are interested in the safety of herbal medicines. T/PCMM is irreplaceable in treating some diseases; but it can easily cause serious problems if confused with other herbal medicines. Accurate identification is essential to ensure their safe use, but up to now, the literature on the authentication of T/PCMM is scant. Thus, we are undertaking a study of 31 T/PCMM originating from plants, animals, minerals, and secreta. Our previous study established microscopic observation as a simple, fast, accurate, and convenient method for identifying and authenticating animal and seed T/PCMM. This study focused on the authentication of flower T/PCMM as a part of the whole study. The flower T/PCMM studies were derived from two species, Datura metel L. (Flos Daturae) and Rhododendron molle G. Don (Flos Rhododendri Mollis). Other species easily confused with these two were also examined and characterized. Using the microscope camera, normal light and polarized light microscopy, we determined the macroscopic and microscopic features of the flowers; in addition, the oil immersion lens was used to study the pollen grain characteristics. The results demonstrated that flower T/PCMM can be identified and authenticated using a light microscope equipped with an oil immersion lens. This same equipment can be easily used to characterize other herbal flower medicines.