Vial Surface Research Articles

Implementation of a high-throughput ion chromatographic assay to assess glass degradation in drug product formulations.

The primary container for parenterals is usually composed of glass. Given the recent industry-wide spike in glass-related problems, assays capable of detecting glass degradation before glass-related particles are visible in solution have practical significance. A rapid, high-throughput ion chromatography method coupled with molybdate reaction is described here for detection and quantitation of silicic acid (soluble form of silica) in complex samples. The method involves ion exchange separation of the silicate anion at high pH followed by a post-column derivatization step with sodium molybdate reagent. The resulting molybdo-silicate complex is detected with high sensitivity in the visible wavelength range at 410 nm and correlates to the level of soluble silica in solution. This assay is high-throughput and amenable for implementation during the early phase of product development. The assay provides a direct measurement to assess potential incompatibility between the formulation and its glass container. The Si levels measured by this method showed a direct correlation to the vial surface morphology changes as monitored by differential interference contrast microscopy. Recently, the pharmaceutical industry has been faced with glass quality challenges that have resulted in many products being recalled from the market. Monitoring levels of soluble silica in solution is critical because silica is the primary component of glass containers used in the pharmaceutical industry. Given this recent industry-wide increase in glass-related problems, assays capable of detecting glass degradation before glass-related particles are visible in solution have practical significance. A rapid assay to detect the soluble form of silica is presented here. The method presented will enable earlier detection of a formulation and container incompatibility instead of waiting until glass-related particles are visible in solution.

Hazardous drug residue on exterior vial surfaces: evaluation of a commercial manufacturing process.

Hazardous drug residue on the exterior surface of drug vials poses a potential risk for exposure of health care workers involved in handling these products. The purpose of this article is to heighten the awareness of this serious issue and to evaluate a commercial manufacturing process for removing and containing hazardous drug (HD) residue on exterior vial surfaces. Additionally, findings from this study are interpreted, incorporated into the current body of evidence, and discussed by experts in this field. This study includes separate evaluations for the presence or absence of surface drug contamination on the vials of 3 HD products: 5-fluorouracil, cisplatin, and methotrexate. The drug products were packaged in vials using a patented prewashing/decontamination method, application of a polyvinylchloride (PVC) base, and use of clear glass vials. An additional step of encasing the vial in a shrink-wrapped sheath was used for 5-fluorouracil and cisplatin. Of all 5-fluorouracil (110 vials), methotrexate (60 vials), and cisplatin (60 vials) tested, only 2 had detectable amounts of surface residue. One 5-fluorouracil vial was found to have approximately 4 mg of 5-fluorouracil on the surface of the vial. The second contaminated vial was cisplatin, which was discovered to have 131 ng of platinum, equal to 200 ng of cisplatin or 0.2 μL of cisplatin solution, on the vial sheath. Using validated extraction and analytic methods, all but 2 of the 230 tested vials were found to be free of surface drug contamination. Pharmacy leaders need to take an active role in promoting the need for clean HD vials. Manufacturers should be required to provide their clients with data derived from externally validated analytic studies, reporting the level of HD contamination on the exterior of their vial products.

Aluminum elution and precipitation in glass vials: effect of pH and buffer species

Inorganic extractables from glass vials may cause particle formation in the drug solution. In this study, the ability of eluting Al ion from borosilicate glass vials, and tendencies of precipitation containing Al were investigated using various pHs of phosphate, citrate, acetate and histidine buffer. Through heating, all of the buffers showed that Si and Al were eluted from glass vials in ratios almost the same as the composition of borosilicate glass, and the amounts of Al and Si from various buffer solutions at pH 7 were in the following order: citrate > phosphate > acetate > histidine. In addition, during storage after heating, the Al concentration at certain pHs of phosphate and acetate buffer solution decreased, suggesting the formation of particles containing Al. In citrate buffer, Al did not decrease in spite of the high elution amount. Considering that the solubility profile of aluminum oxide and the Al eluting profile of borosilicate glass were different, it is speculated that Al ion may be forced to leach into the buffer solution according to Si elution on the surface of glass vials. When Al ions were added to the buffer solutions, phosphate, acetate and histidine buffer showed a decrease of Al concentration during storage at a neutral range of pHs, indicating the formation of particles containing Al. In conclusion, it is suggested that phosphate buffer solution has higher possibility of forming particles containing Al than other buffer solutions.

Novel Mechanism of Glass Delamination in Type 1A Borosilicate Vials Containing Frozen Protein Formulations

Storing protein formulations in the frozen state typically improves stability during long-term storage as a drug substance or as a drug product. The frozen state minimizes chemical degradation and physical instability. However, the frozen state is not an optimal storage condition for the glass vial itself. A significant issue was observed when small, flake-like pieces of glass particles (lamellae) appeared in vials containing thawed protein product. The occurrence of glass particles during freeze-thaw results in product rejection and potentially, adverse events. In recent years, glass flakes due to chemical delamination have been observed in parenteral liquid formulations after long-term storage, resulting in a number of product recalls. In this study, for the first time, glass delamination is reported in pharmaceutical glass vials containing frozen protein formulation, caused by a novel mechanism involving thermally-induced mechanical stress. In this article, a monoclonal antibody drug product in glass vials and the corresponding placebo vials were studied to identify the contributing factors from the freeze-thaw process, such as freezing temperature, the presence or absence of protein, and other handling conditions. Freezing temperature was found to be the most critical factor. Glass lamellae were only observed when the products were frozen to -70 °C, while freezing only to -30 °C did not cause any lamellae formation even after multiple freeze-thaw cycles. Protein concentration and the handling of the vials were also identified as contributing factors. A concentration gradient which formed after freeze-thaw induced a higher rate of lamellae occurrence in a subsequent freeze-thaw cycle compared to vials without the concentration gradient. Analyses by Fourier transform infrared spectroscopy and scanning electron microscopy/energy dispersive spectroscopy confirmed that the flake-like lamellae were thin, flat glass particles. Defects corresponding to the glass flakes were observed by scanning electron microscopy on the inner surface of the vials that contained lamellae. In addition, inductively coupled plasma mass spectrometry testing did not show elevated levels of silicon in the drug product solution, suggesting that the glass lamellae formed in the frozen vials was a local, event-based phenomenon rather than silica dissolution from the product contact surface or glass degradation caused by corrosive attack. These findings can be explained by the same thermally-induced mechanical stress which caused vial breakage. Frozen protein formulations contracted below -30 °C, causing an inward glass deformation and a subsequent rapid movement of the glass when the frozen plug of drug product solution separated from the vial inner surface at approximately -50 to -60 °C. The mechanical stress released during this separation caused vial breakage. The incidence of vial breakage increased with more concentrated product and higher fill volume-to-vial volume ratios. The same mechanism applies to lamellae formation. As the rapid surface separation occurred, small, thin pieces of glass were pulled from the glass surface by the frozen plug, and, as a result, glass lamellae particles appeared in the drug product solution after thawing. In recent years, glass flakes have been observed in parenteral liquid formulations due to chemical delamination during long-term storage, resulting in a number of product recalls. In our study, we discovered a novel mechanism of glass delamination in vials containing frozen protein formulations. This glass delamination mechanism has never been reported before, and we believe this work will benefit the pharmaceutical scientific community, especially the biotechnology and parenteral drug industries. Storing protein formulations in the frozen state typically improves stability during long-term storage as a drug substance or as a drug product. The frozen state minimizes chemical degradation and physical instability. However, the frozen state is not an optimal storage condition for the glass vial itself. In this study, we observed that after thawing, small, flake-like pieces of glass particles (i.e., lamellae) appeared in vials containing frozen protein formulation. To investigate the root cause, we performed a series of freeze-thaw experiments and characterized the lamellae particles, the vial inner surface, and the elemental composition of the solution. The root cause was determined to be mechanical stress caused by thermal contraction of frozen protein formulations below -30 °C. This contraction caused an inward glass deformation on the vial sidewall and, subsequently, the glass vial surface abruptly separated from frozen protein formulation. Under this mechanical stress, small, thin glass pieces were peeled from the vial inner surface by the frozen formulation, causing lamellae formation. The experimental design and results leading to the discovery of the novel glass delamination mechanism are presented in detail in this article.

Investigating factors leading to fogging of glass vials in lyophilized drug products

Vial “Fogging” is a phenomenon observed after lyophilization due to drug product creeping upwards along the inner vial surface. After the freeze-drying process, a haze of dried powder is visible inside the drug product vial, making it barely acceptable for commercial distribution from a cosmetic point of view. Development studies were performed to identify the root cause for fogging during manufacturing of a lyophilized monoclonal antibody drug product. The results of the studies indicate that drug product creeping occurs during the filling process, leading to vial fogging after lyophilization. Glass quality/inner surface, glass conversion/vial processing (vial “history”) and formulation excipients, e.g., surfactants (three different surfactants were tested), all affect glass fogging to a certain degree. Results showed that the main factor to control fogging is primarily the inner vial surface hydrophilicity/hydrophobicity. While Duran vials were not capable of reliably improving the level of fogging, hydrophobic containers provided reliable means to improve the cosmetic appearance due to reduction in fogging. Varying vial depyrogenation treatment conditions did not lead to satisfying results in removal of the fogging effect. Processing conditions of the vial after filling with drug product had a strong impact on reducing but not eliminating fogging.

Suppression of Peptide Sample Losses in Autosampler Vials

Protein or peptide sample losses could accompany all steps of the proteomic analysis workflow. We focused on suppression of sample adsorptive losses during sample storage in autosampler vials. We examined suppression capabilities of six different sample injection solutions and seven types of autosampler vial surfaces using a model sample (tryptic digest of six proteins, 1 fmol per protein). While the vial material did not play an essential role, the choice of appropriate composition of sample injection solution reduced adsorptive losses substantially. The combination of a polypropylene vial and solution of poly(ethylene glycol) (PEG) (0.001%) or a mixture of high concentrated urea and thiourea (6 M and 1 M) as injection solutions (both acidified with formic acid (FA) (0.1%)) provided the best results in terms of number of significantly identified peptides (p < 0.05). These conclusions were confirmed by analyses of a real sample with intermediate complexity (in-gel digest from sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)). Addition of PEG into the real sample solution proved to prevent higher losses, concerning mainly hydrophobic peptides, during up to 48 h storage in the autosampler in comparison with a formic acid solution and even with a solution of highly concentrated urea and thiourea. Using PEG for several months was not accompanied by any adverse effect to the liquid chromatography system.

GRP-178 Surface Contamination with Antineoplastic Drugs in Seven French Hospital Pharmacies

BackgroundDue to their carcinogenic, mutagenic and teratogenic properties, handling cytotoxic drugs presents a risk of occupational exposure for healthcare workers.PurposeTo evaluate and limit occupational risk, environmental monitoring was conducted in...

The analysis and attribution of the time-dependent neutron background resultant from sample irradiation in a SLOWPOKE-2 reactor

The Royal Military College of Canada (RMCC) has commissioned a Delayed Neutron Counting (DNC) system for the analysis of special nuclear materials. A significant, time-dependent neutron background with an initial maximum count rate, more than 50 times that of the time-independent background, was characterised during the validation of this system. This time-dependent background was found to be dependent on the presence of the polyethylene (PE) vials used to transport the fissile samples, yet was not an activation product of vial impurities. The magnitude of the time-dependent background was found to be irradiation site specific and independent of the mass of PE. The capability of RMCC’s DNC system to analyze the neutron count rates in time intervals <1 s facilitated a more detailed data analysis than that obtained in previous DNC systems recording cumulative neutron counts. An analysis of the time-dependent background behaviour suggested that an equivalent of 120 ng of 235U contamination was present on each irradiated vial. However, Inductively Coupled Plasma—Mass Spectroscopy measurements of material leached from the outer vial surfaces after their irradiations found only trace amounts of uranium, 0.118 ± 0.048 ng of 235U derived from natural uranium. These quantities are insufficient to account for the time-independent background, and in fact could not be discriminated from the noise associated with time-independent background. It is suggested that delayed neutron emitters are deposited in the vial surface following fission recoil, leaving the main body of uranium within the irradiation site. This hypothesis is supported by the physical cleaning of the site with materials soaked in distilled water and HNO3, which lowered the background from a nominal 235U mass equivalent of 120 to 50 ng per vial.

Nondestructive Detection of Glass Vial Inner Surface Morphology with Differential Interference Contrast Microscopy

Glass particles generated by glass dissolution and delamination of the glass container for pharmaceutical products have become a major issue in the pharmaceutical industry. The observation of glass particles in certain injectable drugs, including several protein therapeutics, has recently resulted in a number of product recalls. Glass vial surface properties have been suggested to play a critical role in glass dissolution and delamination. Surface characterization of glass container, therefore, is important to evaluate the quality of the glass container. In this work, we demonstrate that differential interference contrast (DIC) microscopy is a powerful, effective, and convenient technique to examine the inner surface morphology of glass vials nondestructively. DIC microscopy does not require the cutting of the glass vial for scanning the inner surface and has sufficient spatial resolution to reveal glass pitting, phase separation, delamination scars, and other defects. Typical surface morphology of pharmaceutical glass vials with different alkalinity are compared and discussed.

Chemical contamination during the preparation of cytotoxics: a multi-site simulation study

BackgroundAlthough an effort is always made to reduce contamination, traces of cytotoxic drugs can be found in the environment. External surfaces of vials can be a source of contamination, but...

Application of X-ray Photoelectron Spectroscopic Analysis to Protein Adsorption on Materials Relevant to Biomanufacturing

X-ray photoelectron spectroscopy (XPS) has been used to analyze the adsorption of a therapeutic monoclonal antibody (mAb), rituximab, and polyclonal human IgG (hIgG) on materials relevant to biomanufacturing of protein drug products. Details of the methods used to obtain qualitative confirmation of protein adsorption, using both the nitrogen (N 1s) signal originating from mAb proteins and an iodine heteroatom label, are presented. Both rituximab and hIgG were found to adsorb to a glass vial surface, vial rubber cap liner, syringe plunger tip, cell culture flask, serological pipette, and microcentrifuge tube. There was no evidence of protein adsorption on samples of polyvinylchloride (PVC) tubing or the barrel of a syringe. Differences in XPS heteroatom peak intensities, based on whether the heteroatom label was added to the protein prior to surface adsorption or after, suggest that adsorbed rituximab on a glass vial surface is in a structural conformation that allows extensive heteroatom labeling. Using a simple uniform overlayer model, the coverage of rituximab on a glass vial surface was determined by XPS to be 3.6 mg/m(2) , a value consistent with that expected for a theoretical monolayer.

Comparison of Contamination Levels on the Exterior Surfaces of Vials Containing Platinum Anticancer Drugs in Japan

Contamination of the external surface of anticancer drug vials supplied to hospital pharmacies has been recognized as a potential health hazard. The aim of this study was to investigate the levels of contamination on the exterior surface of vials containing platinum anticancer drugs in Japan. Platinum contamination on the exterior surface of vials containing cisplatin or carboplatin was examined using products commercially available in Japan. Cisplatin vials from 42 batches (2 drug contents, 10 products and 5 manufacturers) and carboplatin vials from 28 batches (3 drug contents, 7 products and 3 manufacturers) were used. Five vials were randomly sampled from each batch. Exterior contamination levels of 0.070-144 ng/vial as cisplatin and 0.21-1630 ng/vial as carboplatin were detected. Significant differences in the levels of contamination among the batch numbers were observed in 6 of 10 cisplatin products and 6 of 7 carboplatin products. Significant differences in the levels of contamination were observed in 3 cisplatin products with different contents of drug within the vials and 1 carboplatin product with different contents of drug within the vials. Significant differences in the contamination levels among the cisplatin manufacturers but not carboplatin manufacturers were observed. The degree of contamination of the carboplatin products was significantly higher than that of the cisplatin products. In conclusion, external contamination was confirmed in all cisplatin and carboplatin vials tested. The degree of contamination was different among different batch numbers, drug contents, manufacturers, and platinum anticancer drug.

SLIPPERINESS AFFECTS STICKY FEET SELF-CLEANING

Sticky feet are ideal for clinging to vertical surfaces and ceilings, but not so good when it comes to staying clean. ‘Contamination of the adhesive surfaces by loose material can seriously compromise attachment ability’, says Michael Orchard and colleagues from the University of Hull, UK, and the Australian National University. Yet, the sticky feet of ladybirds and ants self clean routinely, so how do they do it? The Anglo-Australian team suspected that the surface upon which an insect is walking could have something to do with their ability to shuck off dirt. ‘We hypothesised that... cleaning would depend on the free surface energy [FSE – a measurement of a surface’s slipperiness] of both the contaminating particles and the surfaces, with surfaces with high FSE (glass) predicted to be better cleaning surfaces than those with low values of FSE', they say (p. 279).Coating glass vials with slippery silicon, the team then systematically contaminated the hairy feet of large and small species of ladybird and the smooth sticky pads of ants with large and small PTFE (slippery) and glass microspheres (less slippery). Next, the team monitored the insects' behaviour and recorded how long it took them to regain their footing on the vertical walls of the untreated and siliconised glass vials.The team report that all of the insects found it easiest to remove glass spheres on a glass surface and it always took them longer to clean feet contaminated with slippery PTFE particles. They also found that small contaminants were the most difficult to dislodge, especially for the smallest insects. Considering the slipperiness (FSE) of the vial surfaces, the team found that the ladybird's hairy adhesive pads shed dirt more easily on the non-slippery (high FSE) glass than on the slippery (low FSE) siliconised vials. However, the slipperiness of the surface did not affect the smooth-padded ants. So the slipperiness of the surface can affect an insect's ability to self-clean, but this depends on which attachment mechanism the insect uses.

DNA Adsorption to the Reservoir Walls Causing Irreproducibility in Studies of Protein–DNA Interactions by Methods of Kinetic Capillary Electrophoresis

Methods of kinetic capillary electrophoresis (KCE) facilitate kinetic studies of protein-DNA interactions and highly efficient selection of DNA aptamers for protein targets. Here, we report a previously unnoticed source of error that affects the precision and accuracy of KCE-based measurements. The error manifests itself in cases that require the use of low concentrations of DNA. In such measurements, the reproducibility of the signal generated by the same fluorescently labeled DNA sample can have a relative standard deviation (RSD) as high as 40%. We have investigated the cause of the irreproducibility and found that it is attributed to DNA adsorption to the surface of the sample vials, in which protein-DNA mixtures are prepared prior to a KCE experiment. The use of commercially available "high DNA recovery" sample vials does not resolve the problem. We have found that the problem can be significantly alleviated by the passivation of the vial surface with blocking agents, such as masking DNA or bovine serum albumin (BSA). The described adsorption of DNA to the surface of sample vials may also be important in other procedures that deal with low DNA concentrations, such as aptamer selection and quantitative PCR.

Verification of surface contamination of Japanese cyclophosphamide vials and an example of exposure by handling

Cyclophosphamide (CP) contamination has been detected in Japanese hospitals. In other countries, the surface contamination of CP vials has been reported; however, the manufacturing process of Japanese CP vials is unknown, so the conditions are not necessarily the same as in other countries. This study aimed to establish whether vial surface contamination also occurs in Japan. Contamination of vial surfaces was examined with a wipe test. Urine samples were taken from a pharmacist, engaged solely in dispensing work, for 29 h. It was also investigated whether CP vials were dispensed during the urine sampling period. In addition, vial surfaces, purposely coated with CP and then washed, were examined using wipe tests. CP was detected at 30-60% in vials, which was 11-62 ng (0.10-0.54 ng/cm(2)). One of the urine samples was contaminated (CP 13.5 ng); this was taken on Day 2 (11:35 AM). CP was not detected among the washed vials. This study shows that the surface of Japanese CP vials was contaminated and that it was probable that healthcare workers were exposed to CP. CP absorption by the pharmacist was probably due to dermal uptake while dispensing. Washing the vial is considered effective to avoid CP exposure. Manufacturers should be more proactive to prevent contamination and healthcare workers should comply with exposure prevention rules. Cytotoxic drugs should be included in institution monitoring lists.

Validated method using liquid chromatography-electrospray ionization tandem mass spectrometry for the determination of contamination of the exterior surface of vials containing platinum anticancer drugs

Contamination of the exterior surface of vials of cytostatic drugs by the drugs themselves is a potential hazard to human health. This study developed a validated method using liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) for the determination of contamination of the exteriors of vials of cisplatin and carboplatin. Large Alpha® sampling swabs were employed to wipe the vial exterior. Cisplatin or carboplatin and gold(III) as an internal standard were derivatized by N,N-diethyldithiocarbamate (DDTC). Pt(DDTC)3+ and Au(DDTC)2+ were monitored by the respective transitions of m/z 639.3–490.9 and 493.0–345.0, respectively. Each separation was completed within 9min using a 3μm particle ODS-column. Calibration curves for cisplatin and carboplatin were linear over concentration ranges of 30–10,000 and 30–30,000pgvial−1, respectively. The accuracies and precisions were 96.1–102.5% and within 8.2% for intra-assay and 99.6–103.3% and within 7.6% for inter-assay, respectively. Their lower limit of quantification was 30pgvial−1. Amounts of 0.17–17.0ngvial−1 as cisplatin and 0.48–794ngvial−1 as carboplatin were detected from the exterior surface of the vials. This validated method using LC-ESI-MS/MS for the determination of platinum anticancer drugs is helpful for monitoring contamination of the exterior surface of drug vials.

Factors Affecting the Chemical Durability of Glass Used in the Pharmaceutical Industry

Delamination, or the generation of glass flakes in vials used to contain parenteral drug products, continues to be a persistent problem in the pharmaceutical industry. To understand all of the factors that might contribute to delamination, a statistical design of experiments was implemented to describe this loss of chemical integrity for glass vials. Phase I of this study focused on the effects of thermal exposure (prior to product filling) on the surface chemistry of glass vials. Even though such temperatures are below the glass transition temperature for the glass, and parenteral compounds are injected directly into the body, data must be collected to show that the glass was not phase separating. Phase II of these studies examined the combined effects of thermal exposure, glass chemistry, and exposure to pharmaceutically relevant molecules on glass delamination. A variety of tools was used to examine the glass and the solution contained in the vial including: scanning electron microscopy and dynamic secondary ion mass spectroscopy for the glass; and visual examination, pH measurements, laser particle counting, and inductively coupled plasma-optical emission spectrometry for the analysis of the solution. The combined results of phase I and II showed depyrogenation does not play a significant role in delamination. Terminal sterilization, glass chemistry, and solution chemistry are the key factors in the generation of glass flakes. Dissolution of silica may be an effective indicator that delamination will occur with a given liquid stored in glass. Finally, delamination should not be defined by the appearance of visible glass particulates. There is a mechanical component in the delamination process whereby the flakes must break away from the interior vial surface. Delamination should be defined by the observation of flakes on the interior surface of the vial, which can be detected by several other analytical techniques.

Container System for Enabling Commercial Production of Cryopreserved Cell Therapy Products

The expansion of cellular therapeutics will require large-scale manufacturing processes to expand and package cell products, which may not be feasible with current blood-banking bag technology. This study investigated the potential for freezing, storing and shipping cell therapy products using novel pharmaceutical-grade Crystal Zenith((R)) (CZ) plastic vials. CZ vials (0.5, 5 and 30 ml volume) with several closure systems were filled with mesenchymal stem cells and stored at either -85 or -196 degrees C for 6 months. Vials were tested for their ability to maintain cell viability, proliferative and differentiation capacity, as well as durability and integrity utilizing a 1-m drop test. As controls, 2 ml polypropylene vials were investigated under the same conditions. Post-thaw viability utilizing a dye exclusion assay was over 95% in all samples. Stored cells exhibited rapid recovery 2 h post-thaw and cultures were approximately 70% confluent within 5-7 days, consistent with nonfrozen controls and indicative of functional recovery. Doubling times were consistent over all vials. The doubling rate for cells from CZ vials were 2.14 + or - 0.83 days (1 week), 1.84 + or - 0.68 days (1 month) and 1.79 + or - 0.71 days (6 months), which were not significantly different compared with frozen and fresh controls. Cells recovered from the vials exhibited trilineage differentiation consistent with controls. As part of vial integrity via drop testing, no evidence of external damage was found on vial surfaces or on closure systems. Furthermore, the filled vials stored for 6 months were tested for container closure integrity. Vials removed from freezer conditions were transported to the test laboratory on dry ice and tested using pharmaceutical packaging tests, including dye ingress and microbial challenge. The results of all stoppered vials indicated container closure integrity with no failures. Pharmaceutical-grade plastic CZ vials, which are commercially used to package pharmaceutical products, are suitable for low-temperature storage and transport of mesenchymal stem cells, and are a scalable container system for commercial manufacturing and fill-finish operation of cell therapy products.

Flight activity of Sitophilus oryzae (L) and Sitophilus zeamais Motsch (Coleoptera: Curculionidae) and its relationship with susceptibility to insecticides

Insect-pest mobility can influence insect susceptibility to the insecticides used to control them. The objective of this work was to evaluate the flight activity of Sitophilus oryzae (L) and Sitophilus zeamais Motsch populations reared on corn and wheat grains, and its relationship with insecticide susceptibility. Unsexed adult insects with ages between 10 and 20 days were placed on a plastic tray. A 40-watt incandescent light bulb was positioned at a 50 cm height relative to the tray. Flight activity was evaluated during 30 min. In the LC50 estimation bioassays, the insects were exposed to dry residues of the organophosphorus insecticide fenitrothion and of the pyrethroid insecticide esfenvalerate on the internal surface of glass vials. Mortality was evaluated 24 h after installation of the experiments. Sitophilus zeamais showed greater flight activity when compared with S.oryzae; likewise, insects reared on corn had greater flight activity than those reared on wheat. Sitophilus oryzae was less susceptible to the insecticides studied than S. zeamais. Adults reared on wheat were more susceptible to the insecticides than those reared on corn. This study demonstrates that the lower flight activity of S. oryzae is related to its greater tolerance to insecticides.

Larval pupation site preference on fruit in different species of Drosophila

AbstractLarval pupation site preference (PSP) of different species of Drosophila was analyzed on fruit in the laboratory. The larvae of D. melanogaster, D. ananassae, D. virilis, D. novamexicana and D. hydei pupated on the surface of glass vials; D. simulans, D. yakuba, D. mauritiana and D. malerkotliana pupated in/on fruit; and D. rajasekari pupated on cotton plugs in all experiments. D. bipectinata larvae changed their preference from fruit in the control to glass surface for all of the fruits tested. The statistical analysis of PSP (glass and fruit) found a significant result in that compared to other species, D. mauritiana and D. ananassae preferred to pupate on cotton compared to the control.