Reliability of Degree-Day Models to Predict the Development Time of Plutella xylostella (L.) under Field Conditions.

The diamondback moth, Plutella xylostella (L.), is a cosmopolitan pest of brassicaceous crops occurring in regions with highly distinct climate conditions. Several studies have investigated the relationship between temperature and P. xylostella development rate, providing degree-day models for populations from different geographical regions. However, there are no data available to date to demonstrate the suitability of such models to make reliable projections on the development time for this species in field conditions. In the present study, 19 models available in the literature were tested regarding their ability to accurately predict the development time of two cohorts of P. xylostella under field conditions. Only 11 out of the 19 models tested accurately predicted the development time for the first cohort of P. xylostella, but only seven for the second cohort. Five models correctly predicted the development time for both cohorts evaluated. Our data demonstrate that the accuracy of the models available for P. xylostella varies widely and therefore should be used with caution for pest management purposes.

Assessing the Total Mortality Caused by Two Species of Trichogramma on Its Natural Host Plutella xylostella (L.) at Different Temperatures.

Trichogramma pretiosum Riley and Trichogramma atopovirilia Oatman & Platner are natural enemies of Plutella xylostella (L.) in Southern Brazil. Laboratory studies to evaluate parasitoids performance under different conditions, such as temperature regimes, are necessary to assess their potential as biocontrol agents of P. xylostella. In most studies involving Trichogramma, parasitism rate is the main parameter used to evaluate parasitoid performance, ignoring that parasitoids can cause egg mortality by feeding on the host content and/or to multiple drilling without laying eggs. This study was conducted to investigate three main issues: how temperature affects T. pretiosum and T.atopovirilia development on eggs of P. xylostella, whether or not these species respond differently to temperature, and how important is the mortality they cause besides parasitism on P. xylostella. Temperature effects (from 10 to 30°C) on development, survival, parasitism rate, mortality, and total mortality caused by T. pretiosum and T. atopovirilia on eggs of P. xylostella were evaluated. Temperature affected the development time, female longevity, parasitism rate, mortality not directly related to parasitoid larval development, and total mortality caused on the host. No significant differences were recorded for the estimated thermal requirements for T. pretiosum and T. atopovirilia. However, the higher mortality caused by T. pretiosum indicates that this parasitoid is the most suitable to be used against P. xylostella. Also, the results suggest that the use of parasitism rate as the only parameter to evaluate the performance of T. pretiosum and T. atopovirilia may underestimate the potential of these parasitoids in regulating pest populations.

Temperature-Dependent Parasitism, Survival, and Longevity of Five Species of Trichogramma Westwood (Hymenoptera: Trichogrammatidae) Associated with Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae).

Egg parasitoids of the genus Trichogramma Westwood play an important role in the control of the velvetbean caterpillar Anticarisa gemmatalis Hübner in soybean crops in Southern Brazil. The effectiveness of Trichogramma species as biocontrol agents is dependent of several factors, but their adaptation to the climatic conditions of the region where they will be released is one of the most important. In this context, this study evaluated the effects of five constant temperatures ranging from 14 to 30°C on parasitism, age-specific survival, progeny production and longevity of Trichogramma pretiosum Riley, Trichogramma atopovirilia Oatman & Platner, Trichogramma acacioi Brun, Moraes & Soares, Trichogramma lasallei Pinto, and Trichogramma rojasi Nagaraja & Nagarkatti. We demonstrate that temperature differently affected the species of Trichogramma investigated when using eggs of the velvetbean caterpillar. We also demonstrate that T. pretiosum and T. atopovirilia are better adapted to a wide range of temperatures than the other species evaluated, and are therefore better suited as biocontrol agents for applied biological control programs of A. gemmatalis.

Modelling reproduction of Plutella xylostella L. (Lepidoptera: Plutellidae): climate change may modify pest incidence levels.

Temperature is considered to be an important abiotic factor influencing insect reproduction. Despite the importance of Plutella xylostella L. (Lepidoptera: Plutellidae) as a pest of brassicaceous crops worldwide, the effects of temperature on its reproduction are not well understood. We evaluated the effect of constant temperatures ranging from 10 to 32.5°C on the reproduction of P. xylostella and developed an oviposition model for the species. The model combined temperature-dependent parameters of total fecundity, age-specific oviposition rate and age-specific survival. Additionally, we modelled population growth as a function of temperature. The estimated parameters allowed us to discuss the possible consequences of global warming on P. xylostella distribution. Temperature affected the length of pre-oviposition after adult emergence, oviposition period, longevity, total fecundity and egg viability. The model predicted that both daily egg production and length of oviposition period decreased at temperatures below 15°C and above 25°C. Population growth increased linearly with temperature in a range from 10°C to 25°C; however, the model predicted a reduction in population growth at temperatures above 28.6°C. Data suggested that temperature plays a critical role in P. xylostella reproduction, and subtle differences in average temperature could have an impact on its population growth. This is especially important in the context of global climate change, which in turn could alter the distribution and abundance of the pest in some regions of the world.

Performance of the wheat armyworm, Pseudaletia sequax Franclemont, on natural and artificial diets.

Armyworms in the genus Pseudaletia Franclemont are important pests of cereal crops worldwide. The development of pest management strategies is largely dependent on studies involving the relationship among the pest, its host plants and natural enemies, as well as its susceptibility to chemical and biological control strategies. Part of these studies requires rearing the species of interest under laboratory conditions, which can be greatly facilitated by the use of artificial diets. In the present study, the effects of three artificial diets on development, survival, reproduction and demographic parameters of P. sequax were compared to a natural host plant, Pennisetum clandestinum. A diet based on pinto beans, wheat germ and torula yeast provided the best results in comparison to those obtained with the host plant. The most important life history parameters used in the evaluation of the nutritional quality of the diets were fecundity, egg viability and pupae deformities. The intrinsic rate of increase and the net reproductive rate were higher when individuals were fed on the artificial diet if compared to the host plant, indicating the suitability of the tested diet for the rearing of P. sequax. This artificial diet has been used successfully for the rearing of P. sequax without any fitness effect for over 18 consecutive generations.

Development and survival of the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Yponomeutidae) as a function of temperature: effect on the number of generations in tropical and subtropical regions.

The diamondback moth, Plutella xylostella (L.), is the most important pest of brassicaceous crops worldwide. Since temperature is the major abiotic factor influencing insect development and thermal requirements may vary among insect populations, it is important to know the effect of temperature on development and survival of a subtropical strain of P. xylostella. Development and survival of the diamondback moth was evaluated under seven constant temperatures ranging from 10°C to 35°C. Development was completed between 10°C and 32.5°C, but at 35°C all individuals died in the larval stage. Data were fitted to one linear and five nonlinear models. Considering as criteria the goodness of fit and the ability to estimate parameters of biological significance, the models Briere-1 and Briere-2 were the most adequate to describe the relationship between temperature and development of P. xylostella. The linear model demonstrated that P. xylostella required 312.5 degree-days above a lower threshold of 6.3°C to complete development. The degree-day model showed that the number of diamondback moth generations in the tropical region of Brazil is nearly twice the number in the subtropical region of the country. This result explains, at least in part, the higher population levels of this species in the tropical region of Brazil, and also demonstrates that P. xylostella is tolerant to a wide range of temperatures (6.1-32.5°C). Therefore, temperature cannot be considered a limiting factor for the occurrence of diamondback moth throughout the year in most regions of Brazil.

Analytical methods for the monitoring of solid phase organic synthesis.

Solid phase synthesis (SPS) is a powerful technique to assemble compound libraries in high-throughput parallel and combinatorial synthesis. The widespread applications of these techniques required the development of analytical methods for both structural elucidation and reaction monitoring. This review covers some recently developed techniques for on-bead analyses together with solution-state ones. Particular emphasis is devoted to software and hardware improvements for automated high-throughput analysis.

Polymer-supported silyl cyanide and silyl azide: useful reagents for solid-phase applications.

The support of a delicate reagent on a solid matrix allows for better and safer handling of the reagent itself. Because we had an interest in silicon-based supported reagents(1) we turned our attention to a polymer-supported trialkylsilyl cyanide and trialkylsilyl azide starting from a commercially available trialkylsilane resin. The supported cyanide was obtained with excellent yield and proved to be shelf-stable. This supported reagent was reacted with a series of aldehydes and ketones yielding the corresponding polymer-supported cyanohydrins in good-to-excellent yields. A stability study on a model cyanohydrin demonstrated that these supported intermediates also can be stored for a prolonged time. For the last step, a cleavage strategy that could release either cyanohydrins or alpha-hydroxy esters was adopted. Finally, we prepared a polymer-supported trialkylsilyl azide, which also proved to be shelf-stable.

Substituted indole-2-carboxylates as potent antagonists of the glycine binding site associated with the NMDA receptor.

A novel series of indole-2-carboxylate analogues of GV150526 (1) in which the propenoic double bond was substituted with different "probes" or replaced by a isosteric cyclopropyl moiety were synthesized and evaluated for their affinity profile in order to obtain further information on the pharmacophoric model of the glycine binding site associated to the NMDA receptor.

Asymmetric synthesis of some substituted-3-phenyl prolines.

The asymmetric synthesis of carboxyphenyl prolines was performed according to Schöllkopf methodology, to prepare possible antagonists of the metabotropic glutamate receptor mGluR1.

Cycloalkyl indole-2-carboxylates as useful tools for mapping the "north-eastern" region of the glycine binding site associated with the NMDA receptor.

A novel series of indole-2-carboxylate analogues of GV 150526 (1) in which the terminal phenyl ring belonging to the side chain present in the position C-3 has been replaced with a bridged cycloalkyl group was synthesized and evaluated for its pharmacological profile. Modelling studies on this class of novel glycine antagonist allowed us to identify an asymmetric lipophilic pocket present in the "North-Eastern" region of the pharmacophoric model of the glycine binding site associated to the NMDA receptor. Among the derivatives prepared, 3-[2-(1-adamantylaminocarbonyl)ethenyl]-4,6-dichloroindole-2 -carboxylic acid 6b and 3-[2-(norbornylaminocarbonyl)ethenyl]-4,6-dichloroindole-2-c arboxylic acid 6l were found to be antagonists acting at the strychnine-insensitive glycine binding site, showing nanomolar affinity for the glycine binding site (Ki = 63 and 19 nM, respectively), coupled with high glutamate receptor selectivity (IC50 > 10(-5) M at the NMDA, AMPA, KA binding sites) and high in vivo potency after systemic administration by inhibition of convulsion induced by NMDA in mice.

In vivo metabolism of a novel cholecystokinin B (CCK-B) antagonist in rat and dog plasma and rat faeces.

1. The in vivo metabolism of a novel CCK-B antagonist ((+)-N-[1-(adamantane-1-methyl)-2,4-dioxo-5-phenyl-2,3,4,5-tetrahydro-1H -1,5-benzodiazepin-3-yl]-N'-phenylurea, GV150013X) was investigated using rat and dog plasma (male and female) and rat faeces samples after administration of GV150013X. 2. Four monohydroxy and four dihydroxy metabolites of GV150013X were identified by comparison with authentic standards using hplc and results from previous in vitro studies. 3. In both rat and dog plasma, GV150013X was converted to one major and other minor metabolites. 4. Qualitatively there is no species or sex differences in the formation of metabolites except that minor metabolite M1 was not detected in dog plasma. 5. Traces of GV150013X and the major metabolite were seen in rat plasma sample 24 h after administration. 6. Hplc with UV and radiochemical detection was used to identify metabolites. Major, non-labelled GV150013X metabolites from rat faeces were collected for characterization by nmr.

Magnetic resonance spectroscopy investigations of brown adipose tissue and isolated brown adipocytes.

Brown adipose tissue and collagenase-isolated brown adipocytes were investigated in rats by means of 1H and 13C nuclear magnetic resonance spectroscopy. After chloroform-methanol extraction of brown adipose tissue, proton and natural abundance 13C spectra of the chloroform fraction showed resonances attributable to triglycerides, and were qualitatively similar to those of the corresponding fraction of white adipose tissue. By means of quantitative analysis of 1H spectra, fatty acid unsaturation and polyunsaturation in triglycerides were found to be lower in brown than white adipose tissue; moreover, unsaturation parameters decreased in triglyceride fatty acids of brown adipose tissue upon norepinephrine administration or cold acclimatization of rats, and were affected by the age of donors. The molar percentage of mono- and polyunsaturated C18 fatty acids in triglycerides was determined from 13C spectra and found to change in the early post-natal period. Isolated, agarose-embedded brown adipocytes from 4-day-old rats showed a number of peaks in the carbohydrate region of 1H spectra that were not present in spectra of white adipocytes and almost disappeared in brown fat cells of older animals. These peaks could be restored by insulin exposure. Natural abundance 13C spectra of isolated brown adipocytes were resolved enough to allow unambiguous assignment of resonances to carbons of fatty acids, glycerol, glucose, ethanolamine, and choline. Calculation of the mono- to polyunsaturated fatty acids ratio in the cells was also performed. Nuclear magnetic resonance spectroscopy is a useful tool for the investigation of brown adipose tissue and adipocytes therefrom.

Synthesis and antimicrobial activity of DNA-gyrase inhibiting derivatives of 4-oxo-1,4-dihydro-3-pyridinecarboxylic acid.

A series of 6-substituted-1-aryl-4-oxo-1,4-dihydronicotinic acids were synthesised as monocyclic analogues of the quinolones. The 6-(2-aryl-1-methylethenyl)- and of the 6-(2-arylethenyl)-substituted compounds were shown to possess antibacterial properties that correlate with DNA gyrase inhibitory activity. Differently from the quinolones the antimicrobial activity of the compounds of this study is predominantly against Gram positive strains. The structure-activity relationships ascertained for these monocyclic compounds differ from those established for the quinolones.