The immature stages of some Phlebotomine sandflies from Brazil (Diptera: Psychodidae)

Immature stages of Lutzomyia anduzei (Rozeboom), L.antunesi (Coutinho), L. flaviscutellata (Mangabeira), Psychodopygus davisi (Root), Ps.paraensis (Costa Lima) and Ps.lainsoni Fraiha & Ward are described from specimens reared in the laboratory. The Lutzomyia species are members of the intermedia group, though L. flaviscutellata larvae more closely resemble those of Psychodopygus species. The larvae of L.anduzei and L. antunesi are separable on minor setal differences and are similar to previously described members of the intermedia group. Ps. paraensis is distinguishable from the other two Psychodopygus species described, by the absence of prothoracic seta 2. Head seta 5 of Ps.davisi is about twice the length of that in Ps. paraensis and larvae of Ps.lainsoni are pale and characterized by colourless body setae 4 and 10. A key to the fourth instar larvae is given which includes all the known larvae of the intermedia group and of the genus Psychodopygus. Morphological differences in the Psychodopygus larvae do not appear to reflect the separation of the adults into series.     

Residual effects of High Temperature Pre-Treatments on the Germination of Celery Seeds (Apium graveolens)

Celery seeds (Apium graveolens L.) were allowed to imbibe in the dark for different periods at 28. 32. 37 or 41°(the high temperature pre-treatmem or HTP) prior to transfer to 15, 17, 19.5 or 22°C in white light (the low temperature treatment or LTT). The effect of HTP's at 28. 32 and 37°C was to lower the upper temperature limit for germination and this effect increased with increase in the temperature and duration of the HTP. Increasing exposure to an HTP of 41 °C, however, did not appear to lower the upper temperature limit for germination but reduced the viability of the seeds. This trend of increased inhibition of germination caused by increasingly higher temperatures was reversed when the transfer was to a 22°C LTT after a 4 day HTP at 37°C. When the temperature of (he HTP was relatively low and transfer was to a low LTT. or if the HTP was of a brief duration, the rate of germination was increased as compared to seeds not given an HTP. However, when the temperature and duration of the HTP were increased, the rate of germination became slower than that of seeds not given an HTP, i.e. the time taken for the seeds to recover from the HTP-induced dormancy increased with the temperature and duration of the HTP. The decrease in the germination rate was caused by a delay in the start and not a slowing of the rate of embryo elongation within the seed.     

Modeling mate-finding behavior of the swarming polychaete,Nereis succinea,with TangoInSilico,a scientific orkflow-based simulation system for sexual searching

Summary

Pheromones can be used as attractants for the opposite sex in many environments; however, little is known about the search strategies employed in responding to pheromones in the marine environment. The spawning behavior of males of the polychaete Nereis succinea is known to be triggered at close range by a high concentration (>～10^?7 M) of pheromone, cysteine glutathione disulfide (CSSG), released by females. Since CSSG also causes acceleration of swimming and increased turning, in addition to eliciting ejaculation, we proposed the hypothesis that these behaviors elicited by low concentrations of pheromone can be used by males to find females. The current study develops a computer simulation model of male and female N. succinea behavior for testing whether male responses to low concentrations of CSSG can facilitate finding females. Video recording of female swimming behavior in the field showed spontaneous loops, spirals, and circles that have been incorporated into the model. The scientific workflow paradigm within which the computer model has been developed also incorporates a data provenance system to enable systematic replay and testing of responses to individual parameters. Output of the model shows complex turning behavior leading to successful mating encounters at concentrations as low as 3×10^?9 M CSSG. Behavior resembling the output of the model was recorded in field observations. Application of the model in the future will be used to determine what pheromone concentrations produce significant increases in the probability of mating encounters.     

INDUCTION OF OVARIAN DEVELOPMENT IN AUTOGENOUS AEDES ATROPALPUS BY JUVENILE HORMONE AND 20-HYDROXYECDYSONE

Aedes atropalpus is an autogenous mosquito characterized by a first gonadotropic cycle which results in approximately 200 mature oocytes without a bloodmeal. Ovarian development is completely inhibited if these animals are decapitated or ligated between the thorax and abdomen shortly after adult emergence. Injection of 4.8 ng of 20-hydro- xyecdysone into decapitated females 12 h after eclosion restores ovarian development in all females so treated. However, the same amount of 20-hydroxyecdysone injected into isolated abdomens obtained shortly after adult emergence had no discernible effect on vitellogenesis. In contrast, all abdomens which received 0.5 ng of topically applied JH I followed by the injection of 4.8 ng 20-hydroxyecdysone produced mature oocytes. Isolated abdomens were also capable of oocyte maturation when treated with excess amounts of JH alone; JH I was the most effective followed by JH II and then JH III.

Polyacrylamide gel electrophoretic analysis of vitellin extracted from the ovaries of hormonally-treated animals did not reveal any qualitative differences compared to intact normal controls. However, less yolk protein was present in the former. This was verified by counting the number and measuring the size of ovarian follicles in individual females.     

Mutants impaired in vacuolar metal mobilization identify chloroplasts as a target for cadmium hypersensitivity in Arabidopsis thaliana

Cadmium (Cd) is highly toxic to plants causing growth reduction and chlorosis. It binds thiols and competes with essential transition metals. It affects major biochemical processes such as photosynthesis and the redox balance, but the connection between cadmium effects at the biochemical level and its deleterious effect on growth has seldom been established. In this study, two Cd hypersensitive mutants, cad1‐3 impaired in phytochelatin synthase (PCS1), and nramp3nramp4 impaired in release of vacuolar metal stores, have been compared. The analysis combines genetics with measurements of photosynthetic and antioxidant functions. Loss of AtNRAMP3 and AtNRAMP4 function or of PCS1 function leads to comparable Cd sensitivity. Root Cd hypersensitivities conferred by cad1‐3 and nramp3nramp4 are cumulative. The two mutants contrast in their tolerance to oxidative stress. In nramp3nramp4, the photosynthetic apparatus is severely affected by Cd, whereas it is much less affected in cad1‐3. In agreement with chloroplast being a prime target for Cd toxicity in nramp3nramp4, the Cd hypersensitivity of this mutant is alleviated in the dark. The Cd hypersensitivity of nramp3nramp4 mutant highlights the critical role of vacuolar metal stores to supply essential metals to plastids and maintain photosynthetic function under Cd and oxidative stresses.     

State‐dependent attacks in a mosquito

Mosquito biting frequency and meal size are considered to be important parameters in the epidemiology of insect‐vectored diseases such as malaria. Because both parameters are likely to depend on the size and energetic state of adult mosquitoes, the present study investigates the effects of body size and energy state on attack behaviours in the malaria mosquito, Anopheles gambiae. Attack rates are measured as well as total time spent before giving up for individual females when provided with an unobtainable human hand (i.e. mosquitoes are dislodged every time that they land). The factorial design considers two body sizes, small and large, as well as three sugar deprivation states, 0, 1 and 2 days. The results reveal a positive effect of size on attack rate and a nonlinear effect of energy state, where mosquitoes of intermediate energy state show lower attack rates than either 2‐day food‐deprived or nondeprived mosquitoes. Moreover, attack rate is negatively associated with persistence time in nondeprived and 2‐day food‐deprived Anopheles but is unrelated to persistence time in 1‐day food‐deprived mosquitoes, Interestingly, although persistence times are generally inversely related to attack rates, they are not significantly influenced by either energetic or size states.