Degradation Studies of the Non-lethal Bird Repellent,Methyl Anthranilate

Methyl anthranilate (MA), a food grade flavor and fragrance additive, has been reported to be an effective non-lethal bird repellent in a variety of situations. Despite the experimental success of MA, field studies have yielded widely differing levels of efficacy. Diminished efficacy in some field trials probably results from the failure of specific formulations to retain or protect the active ingredient under natural conditions. Therefore, a clearer understanding of the physical and chemical factors affecting the stability of MA is needed. We undertook a series of laboratory studies on hydrolysis, photolysis and microbial degradation of MA, the results of which could be useful in the development of appropriate formulation strategies and residue analyses. We found the n-octanol:water partition coefficient, (P) to be 84. MA is not subject to hydrolysis at 25°C in phosphate buffer media at pH 5·0, 7·0 and 9·0. MA slowly photodegrades under simulated UV ‘sunlight’. Forty-four percent of MA is lost after 432 h illuminance at 1·25 mW cm⁻², which is equivalent to approximately 1200 h natural sunlight (40°N, noontime, June). Kinetic data indicate that the initial step of photolysis, subsequent to excitation, is a second-order reaction with respect to MA. A major photodegradation product appeared in an amount of about 10% of the mass balance and was determined to be an oxidized trimer of MA. MA is primarily affected by aerobic microbial degradation. For a 12:12 h light:dark, under laboratory illumination, 12% of water-solubilized material can be lost in the first seven days. Losses were 30% and 42% at 16 and 27 days, respectively. Under conditions of optimal bacterial growth (warmth and darkness) loss of MA was 22% at nine days and 100% by 20 days. The susceptibility of MA to microbial degradation is promising for the prospects of developing formulated, environmentally safe, bird repellents.     

Intravarietal level of aluminum resistance in cereal crops

The relative growth parameters of seedlings of some oat (Avena sativa L.) and barley (Hordeum vulgare L.) varieties from different intravarietal seed fractions in the absence or presence of 1–2 mM aluminum (Al) sulfate were investigated in several experiments using the solution‐paper culture technique. There were statistically significant differences in Al‐resistance level of seeds, which differ by its weight, place on ear, place, and year of reproduction and rate of germination. The data suggest that the level of Al resistance/susceptibility is not determined by genotype exactly, but may be modified by some endogenous chemical and biochemical factors (for example, content of seed storage proteins, inhibitors of germination, natural plant growth regulators, etc.). Such non‐uniformity of seeds within cultivars may be used for investigation of plant Al‐resistance mechanisms.     

Acute toxicity of the bird repellent,methyl anthranilate,to fry of Salmo salar,Oncorhynus mykiss,Ictalurus punctatus and Lepomis macrochirus

Several laboratory and field studies have shown methyl anthranilate to be an effective, non-toxic and non-lethal bird repellent, with application potential for protecting crops, seeds, turf and fish stocks from bird damage. Furthermore, methyl anthranilate can be added to liquids for the purposes of protecting migratory birds, e.g. addition to waste water associated with mining and to standing water pools at airports. Mammalian toxicity data are favorable. Methyl anthranilate is used as a fragrance and food flavoring and is GRAS listed by the US Food and Drug Administration. Despite the favorable outlook for methyl anthranilate's use as a safe repellent, no data exist on its environmental fate and effects. We have tested the acute toxicity of methyl anthranilate in a static system against the fry of four species of fish. The LC₅₀ at 24 h for Atlantic salmon (Salmo salar L.) was 32.3 mg liter^?1, with the no observable effect limit at 6 mg liter^?1. The LC₅₀ at 24 h for rainbow trout (Oncorhynus mykiss Richardson) was 23.5 mg liter^?1, with the no observable effect limit at 5 mg liter^?1. The LC₅₀ at 24 h for channel catfish (Ictalurus punctatus Raf.) was estimated to be 20.1 mg liter^?1, with the no observable effect limit at 7 mg liter^?1. The LC₅₀ at 24 h for bluegill sunfish (Lepomis macrochirus Raf.) was estimated to be 19.8 mg liter^?1, with the no observable effect limit at 7 mg liter^?1..     

Human food flavor additives as bird repellents: I. Conjugated aromatic compounds

Avian repellents derived from natural products and human food flavorants may be less expensive to register under United States environmental pesticide registration requirements. However, one difficulty faced by workers attempting to target repellents for development is the need to screen large numbers of compounds for activity, as well as consideration of formulation and environmental constraints. In this study, we compare the bird repellent activity of aldehyde-based human food additives and compare the levels of activity with our previously elucidated model for structure–activity relationships (SAR) for bird repellents. We find that a previously elucidated SAR model for identifying acetophenone and anthranilate bird repellents is applicable to predicting the activity of aromatic aldehyde flavorants as well. In particular, of the nine flavorants tested, four, benzaldehyde, cinnamaldehyde, o-tolualdehyde, and o-anisaldehyde, warrant further consideration as bird repellents. L© 1999 Society of Chemical Industry     

Sperm cryopreservation in the Far‐Eastern wildcat (Prionailurus bengalensis euptilurus)

The Far‐Eastern wildcat (Prionailurus bengalensis euptilurus) is a rare and poorly investigated nondomestic felid species. An attempt of freezing and cryopreserving Far‐Eastern wildcat spermatozoa in CaniPlus Freeze (CPF) medium is reported. Sperm was collected by electroejaculation from five adult Far‐Eastern wildcat captive‐born males. Epididymal spermatozoa from five adult randomly bred domestic cat males were used as a reference. The viability of frozen–thawed spermatozoa evaluated by double staining with SYBR Green I and PI followed by the subsequent confocal laser scanning microscopy (CLSM) was 38.2% ± 3.0% for the domestic cat and 38.0% ± 10.2% for the Far‐Eastern wildcat. The motility of frozen–thawed spermatozoa was 30.8% ± 9.8% for the domestic cat and 33.7% ± 15.1% for the Far‐Eastern wildcat. Sperm morphology was assessed by light microscopy. The total percentage of normal spermatozoa after freezing and thawing was 51.9 ± 5.9 for the domestic cat and 55.0% ± 6.4% for the Far‐Eastern wildcat. Defects of flagella were the most frequently observed abnormalities in both species (32.2% ± 4.8% and 30.8% ± 4.4% of all reported anomalies for the domestic cat and Far‐Eastern wildcat, respectively). Domestic cat epididymal and Far‐Eastern ejaculatory spermatozoa fertilized in vitro‐matured oocytes of the domestic cat (30.0% ± 5.5% and 35.5% ± 15.0%, respectively). Taken together, these results suggest that the freezing of Far‐Eastern wildcat spermatozoa with CPF medium is a suitable method for Felidae cryopreservation.     

Effects of slow freezing and vitrification on embryo development in domestic cat

Cryopreservation of gametes and embryos is used to maintain genetic diversity of domestic and wild felids. However, felid oocytes and preimplantation embryos contain large amount of intracellular lipids, which affect their cryosensitivity. The objective was to compare the effects of slow freezing and vitrification and to study lipid phase transition (LPT) during cooling in cat embryos. In vitro-derived embryos were cultured 48 hr up to 4–8 cell stage, thereafter were either slow frozen or vitrified. Propylene glycol (PG) alone was used as a cryoprotective agent (CPA) for slow freezing, and a mixture of PG and dimethyl sulfoxide (DMSO) were used as CPAs for vitrification. After thawing/warming, embryos were in vitro cultured additionally for 72 hr. The total time of in vitro culture was 120 hr for all the groups including non-frozen controls. Effects of both cryopreservation procedures on the subsequent embryo development and nuclear fragmentation rate in embryonic cells were compared. There was no significant differences among the percentages of embryos achieved morula and early blastocyst stage in frozen-thawed group (36.4% and 20.0%), in vitrified-warmed group (34.3% and 28.6%) and in controls (55.6% and 25.9%). Cell numbers as well as nuclear fragmentation rate did not differ in these three groups. Average lipid phase transition (LPT) temperature (T*) was found to be relatively low (–2.2 ± 1.3°C) for the domestic cat embryos. It is supposed that the low LPT of LDs may provide a good background for successful application of slow freezing to domestic cat embryos. Generally, our study indicates that slow freezing and vitrification are both applicable for domestic cat embryo cryopreservation.     

Cryopreservation and In Vitro culture of Preimplantation Embryos in Djungarian Hamster (Phodopus sungorus)

Although embryo cryobanking was applied to Syrian golden and to Campbell's hamsters, no attempt has been made at freezing embryos in Djungarian hamsters. Four‐cell stage embryos were flushed from the reproductive ducts of pregnant females before noon of the third‐day post coitum and frozen in 0.25‐ml straws according to standard procedures of slow cooling. A mixture of permeating (ethylene glycol) and non‐permeating (sucrose) cryoprotectants was used. The thawing was performed by incubating at RT for 40 s followed by 40 s in a water bath at 30.0°C. Most (66.7%) of the non‐frozen four‐cell embryos developed up to the morula stage in rat one‐cell embryo culture medium (R1ECM). The use of hamster embryo culture medium (HECM) yielded fewer morulas (18.2%) during the same 24‐h period of culture. The rate of embryo's surviving the freezing–thawing procedures, as estimated by light microscopy, was 60.7–68.8%. After 24‐h culturing in R1ECM, 64.7% of frozen–thawed four‐cell embryos developed and all of them reached the morula stage. Supplementation of R1ECM with GM‐CSF (2 ng/ml) improved the rate of Djungarian hamster frozen–thawed embryo development: 100% of the four‐cell stage embryos developed, 50% of them achieved the morula stage, and 50% developed even further and reached the blastocyst stage within 24 h of culturing. This study reports the world's first successful transfer of frozen–thawed Djungarian hamster embryos yielding term pups. Taken together, the results of this study demonstrate the possibility of applying some key reproductive technologies, that is, embryo freezing/cryopreservation and in vitro culture, to Djungarian hamsters.