Effects of water availability on emerald ash borer larval performance and phloem phenolics of Manchurian and black ash

The invasive emerald ash borer (EAB) beetle is a significant threat to the survival of North American ash. In previous work, we identified putative biochemical and molecular markers of constitutive EAB resistance in Manchurian ash, an Asian species co‐evolved with EAB. Here, we employed high‐throughput high‐performance liquid chromatography with photodiode array detection and mass spectrometry (HPLC‐PDA‐MS) to characterize the induced response of soluble phloem phenolics to EAB attack in resistant Manchurian and susceptible black ash under conditions of either normal or low water availability, and the effects of water availability on larval performance. Total larval mass per tree was lower in Manchurian than in black ash. Low water increased larval numbers and mean larval mass overall, but more so in Manchurian ash. Low water did not affect levels of phenolics in either host species, but six phenolics decreased in response to EAB. In both ashes, pinoresinol A was induced by EAB, especially in Manchurian ash. Pinoresinol A and pinoresinol B were negatively correlated with each other in both species. The higher accumulation of pinoresinol A in Manchurian ash after attack may help explain the resistance of this species to EAB, but none of the responses measured here could explain increased larval performance in trees subjected to low water availability.     

Thermal physiology and the origin of terrestriality in vertebrates

The adaptive reasons for the evolutionary transition between obligatorily aquatic lobe-finned fish and facultatively terrestrial early tetrapods have long been debated. The oldest adequately known amphibians, Acanthostega and Ichthyostega , from the final stage in the Upper Devonian (Famennian), can be clearly distinguished from the most advanced choanate sarcopterygian fish from the next older stage (Frasnian) by the presence of large pectoral and pelvic girdles, limbs generally resembling those of later Palaeozoic land vertebrates, and the absence of bones linking the back of the skull with the shoulder girdle. Upper Devonian and most Lower Carboniferous amphibians, like their aquatic predecessors, differed significantly from modern amphibians in their much larger size, up to a metre or more in length. Animals of this size, resembling modern crocodiles and the marine iguana, could have raised their body temperatures by basking in the sun and sustained them upon re-entry into the water. It is hypothesized that the physiological advantages of thermoregulation were a major selective force that resulted in the increasing capacity for the ancestors of tetrapods to move into shallow water, and later to support their bodies against the force of gravity and increase the size and locomotor capacities of the limbs.  © 2005 The Linnean Society of London, Zoological Journal of the Linnean Society , 2005, 143 , 345–358.     

Spatial distribution of banana skipper （Erionota thrax L.） （Lepidoptera： Hesperiidae） and its parasitoids in a Cavendish banana plantation, Penang, Malaysia

Spatial distribution of immatures of the banana skipper （Erionota thrax L.） and their parasitisms from three major parasitoids were studied in a Cavendish banana plantation from April 2004 to December 2004. Infestation levels and parasitism of E. thrax life stages were recorded from bunched plants （BP）, flowering plants （FP）, preflowered plants （PF）, broad leaf followers （BLF） and narrow leaf followers （NLF）, as well as on well managed and poorly managed plants. Mean numbers of the immatures and numbers parasitized from the nine blocks in the plantation were fitted to four dispersion indices. Significant numbers of E. thrax immatures and those parasitized by Ooencyrtus erionotae, Cotesia erionotae and Brachymeria albotibialis were recorded from BLF and PF; no eggs were found on BP and FP. Although infestation was higher on well managed plants, only larval parasitism was significantly different. Three of the four indices indicated that eggs and larvae were random while all the indices showed pupae to be clumped. Parasitized eggs and pupae were clumped （4/4 indices） while 3/4 indices revealed a random pattern for parasitized larvae.     

Demographics of Common Snapping Turtles (Chelydra serpentina): Implications for Conservation and Management of Long-lived Organisms

SYNOPSIS. A study of common snapping turtles conducted from1975 through 1992 in southeastern Michigan provided sufficientdemographic data to examine how life history characteristicsmay constrain population responses of long-lived organisms.Females reached sexual maturity between 11 and 16 years of age.Minimum reproductive frequency was less than annual (0.85),and nest survivorship over 17 years ranged from 0 to 64% andaveraged 23%. Survivorship of yearlings had to be estimatedsince hatchlings can pass through the mesh on traps. Actualsurvivorship of juveniles was over 0.65 by age 2 and averaged0.77 between the ages of 2 and 12 years. Annual survivorshipof adult females ranged from 0.88 to 0.97. A life table forthe population resulted in a cohort generation time of 25 years.Population stability was most sensitive to changes in adultor juvenile survival, and less sensitive to changes in age atsexual maturity, nest survival or fecundity. An increase inannual mortality of 0.1 on adults over 15 years of age withno density-dependent compensation would halve the number ofadults in less than 20 years. The results from the present study indicate that life historytraits of long-lived organisms consist of co-evolved traitsthat severely constrain the ability of populations to respondto chronic disturbances. Successful management and conservationprograms for long-lived organisms will be those that recognizethat protection of all life stages is necessary. Without protectionof adults and older juveniles, programs that protect nests andheadstart hatchlings have a low probability of success. Carefullymanaged sport harvests of turtles or other long-lived organismsmay be sustainable; however, commercial harvests will certainlycause substantial population declines