Field evaluation of alpha-chlorohydrin against the Indian mole rat: studies on toxic and antifertility effects

Field acceptance and efficacy of a toxicant-sterilant, alpha-chlorohydrin (α-CH), at its 0.5% concentration in bait were evaluated against rodents in sugarcane fields which harboured high populations of the Indian mole rat Bandicota bengalensis (Trap Index (TI) = 53.6 rats/100 traps/24 h) followed by that of the Indian bush rat Golunda ellioti (TI = 28.6) and soft-furred field rat Rattus meltada (TI = 1.8). Acceptance of the α-CH bait by rodents in the fields was evident from complete consumption of the offered bait at most of the baiting points. The treatment (72 h exposure to the poison bait) resulted in 63.7% to 82.9% rodent mortality. Survey of the mature sugarcane crop revealed that the percentage of rodent cut canes in the treated fields (7.6% to 16.2%) was significantly less than that of the reference fields (26.3%). Most of the surviving male B. bengalensis, captured after 15 days of the treatment, had developed sterility as revealed by the functional abnormalities in their testes and epid-idymides. They showed decreased thickness of the seminiferous tubules, lower population of spermatogenic cells, cauda epididymal sperm concentration, live sperm and sperm mortality. A nonsignificant positive correlation between the testicular weight and sperm motility in males from treated fields indicated the effect of α-CH at maturation level in the cauda epididymides. Overall, it was evident that a significant proportion of the surviving B. bengalensis had become permanently sterile as a consequence to the development of spermatocoeles in the caput epididymides and the remaining had significantly low numbers (< 30%) of motile sperm in their cauda epididymides which was, obviously, a handicap for successful fertilisation.     

NOTES ON THE FEEDING HABITS OF HOUSE-RATS IN RANGOON, BURMA

During a poison campaign against house-rats, particularly of the species Bandicota bengalensis, Rattus rattus nr. khyensis and R. exulans concolor, a number of incomplete experiments were carried out on feeding habits and the take of poison.
The rats showed a reaction to new objects similar to that of R. norvegicus in England.
A marked preference was shown for boiled rice over any other available foodstuff. The amount eaten was roughly proportional to the surface area of the rat. Barium carbonate in boiled rice was an acceptable poison bait, and the optimum concentration of poison was in the range 10–20%.     

Laboratory evaluation of a toxicant-sterilant, alpha-chlorohydrin, for the control of Indian mole rat Bandicota bengalensis

A toxicant-sterilant, alpha-chlorohydrin, was evaluated against the Indian mole rat Bandicota bengalensis and the ship or house rat Rattus rattus. It caused 100% mortality of B. bengalensis at 100 mg/kg but no mortality was observed in R. rattus even at 300 mg/kg. The acute oral LD₅₀ for B. bengalensis was found to be 82 mg/kg. The survivors of B. bengalensis, which received 60 - 90 mg/kg of alpha-chlorohydrin by oral intubation, showed dose-dependent decreases in testicular weight, and cauda epididymal sperm concentration, live sperm count and sperm motility. The values of these parameters indicated that mole rats receiving the above doses would be sterile. In contrast, these changes were observed in R. rattus only at doses of 200 and 300 mg/kg. The toxic and antifertility effects of alpha-chlorohydrin observed on B. bengalensis suggest that it should be evaluated for the management of this species under held conditions.     

Effectiveness of protein baits on melon fly and oriental fruit fly (Diptera: Tephritidae): attraction and feeding

Attraction and feeding responses of oriental fruit fly, Bactrocera dorsalis (Hendel), and melon fly, Bactrocera cucurbitae (Coquillett), were determined for different protein baits. In separate choice attraction assays for each species, significantly more flies arrived at stations with bait than water, but no differences existed among baits of GF-120 Fruit Fly Bait, GF-120 NF Naturalyte Fruit Fly Bait, Provesta 621 autolyzed yeast extract, and Mazoferm E802. In comparison with B. dorsalis, B. cucurbitae had 2.8 times more responders and a 4.8 times better discrimination between baits and water. In a second attraction assay with only B. dorsalis, volume of bait was negatively correlated to numbers of flies alighting on the bait. Feeding assays for both species demonstrated that time spent feeding and duration on a leaf were both significantly affected by bait type. B. dorsalis fed the longest on Provesta 621, with significantly less feeding on the other baits, and with all baits resulting in more feeding than water. The longest feeding times for B. cucurbitae resulted with Mazoferm E802 and Provesta 621, and all baits except GF-120 NF resulted in eliciting a significantly longer feeding duration than water. In separate toxicology assays for each species, significantly higher mortality resulted from bait formulations containing spinosad compared with blank baits, but no differences existed between GF-120 and GF-120 NF formulations. The differences are discussed between the two Bactrocera species primarily in regard to bait preference, extent of response, and previous work on laboratory flies.     

Do colours that deter birds affect cereal bait acceptance by possums (

Poisonous baits used for pest control in New Zealand commonly contain green dye and cinnamon oil to make them less attractive to birds. Research aimed at reducing the impact of poison based pest control on birds has shown that some birds are initially deterred from feeding on blue or, to a lesser extent, green coloured food and are attracted to yellow or red food. We determined whether colours that deter or attract birds affected the acceptance of non-toxic and toxic cereal baits by captive brushtail possums (Trichosurus vulpecula). Individual possums were offered, daily, a choice between a standard green dyed non-toxic cereal bait and either a blue dyed(17 possums) or yellow dyed non-toxic bait (16 possums) for 10 days. Following this, for the first group of 17 possums, 1080 toxin was added to either the green bait (9 possums) or blue bait (8 possums) and possums were offered the green versus blue choice again. Two additional groups that had not previously been fed cereal baits were also given a choice between blue and green baits, one of which was toxic. All possums offered non-toxic bait ate less on the first day of presentation than on subsequent days. There was no difference in acceptance of either blue or yellow coloured non-toxic bait compared to the standard green non- toxic bait on any days. Bait colour appeared to be unimportant in cereal bait choice and did not deter possums from eating any of the baits. The addition of toxin to baits did not significantly alter bait choice in any groups, although some individuals which had no previous experience with baits ate more toxic than non-toxic bait. These data suggest that adding a stronger bird deterring colour (i.e., blue) to poisonous baits is unlikely to adversely affect the acceptance of baits by possums.     

Evaluating seasonal bait delivery to badgers using rhodamine B

In the UK and Ireland, research on the control of bovine tuberculosis in badgers includes the development of a palatable bait for oral delivery of a vaccine and a means of its deployment in the field. In the present study, we carried out field deployment of bait according to the established method of bait marking in early spring and early summer to compare the effects of seasonality on bait uptake rates. All baits contained rhodamine B (RhB) which was subsequently detected in the hair and whiskers of captured badgers. During the 8 days of bait feeding at 14 badger setts, 99% of baits deployed in spring, and 100% of those deployed in summer were removed. The presence of RhB in captured badgers indicated high rates of uptake amongst adult badgers in spring (93%) and summer (98%). Only cubs captured in summer showed evidence of having taken bait (91%). Between 67% and 100% of each social group was estimated to have taken bait. The detection of RhB in 96% of badgers captured at outlier setts, where bait was not fed, suggested that deployment at main setts alone may be sufficient to target a relatively high proportion of the badger population. The number of baits deployed per marked badger suggested that a similar level of uptake might be achievable using fewer baits. The results clearly demonstrate the potential value of the bait-marking methodology for delivering vaccine baits to badgers during spring and summer, but that deployment in early summer is necessary to target cubs.     

Hunger and light level alter response to bait by Pacific halibut: laboratory analysis of detection, location and attack

Laboratory experiments with Pacific halibut Hippoglossus stenolepis revealed that hunger level had a significant effect on the first detection of bait, the number of baits located and attacked, the time required to locate and attack baits and handling times. In all cases, feeding motivation and efficiency increased with hunger. Light level influenced general locomotory activity and location and attacks on baits, but not detection or handling times. The effect of light was interactive with fish hunger level. Hungry fish could locate and consume baits in all light levels, ranging from daylight conditions to near darkness (10⁻⁸ µmoles photons m⁻² s⁻¹), but location, attack and handling times were all significantly elevated in low light conditions, and attack rates were significantly reduced. In the dark, only 50% of the baits were located and only 17% were attacked. Performance metrics were relatively similar among three higher light treatments (10⁻⁵, 10⁻³ and 10⁻¹ µmoles photons m⁻² s⁻¹) where bait location and attack were more efficient. Active space and effective area associated with baited fishing gear will vary because hunger and light levels affect variation in bait detection, locomotion and feeding behaviour. Consequently, fishing activity and stock assessments that depend upon bait may be compromised by spatial and temporal variation in prey abundance, time of day, season, depth and other environmental variables that influence feeding motivation and efficiency.     

Attraction and feeding responses of Mediterranean fruit fly and a natural enemy to protein baits laced with two novel toxins,phloxine B and spinosada

Studies were conducted to determine attraction and feeding propensity of Mediterranean fruit fly, Ceratitis capitata (Wiedemann), to different protein bait mixtures with and without the insecticides malathion, spinosad, and phloxine B. Protein baits were more attractive to females than to males. Protein-starved females responded more than protein-fed females. The type of protein (USB^® yeast hydrolysate enzymatic, Mazoferm^®E802, Nu-Lure^®Insect Bait, or Provesta^® 621 autolyzed yeast extract) in the bait had a major influence on C. capitata attraction, which was strongest to fresh Provesta. Aged baits (four day-old) were not as attractive as fresh baits. In feeding propensity studies, highest response was observed for USB protein. On the basis of attraction and feeding responses Provesta (attraction and feeding) and USB (feeding) outperformed the standard Nu-Lure. Protein-starved flies were much more likely to feed on protein compared to protein-fed flies. For protein-starved flies, a mixture of Provesta and malathion repelled fruit flies, compared to a mixture of Provesta and spinosad or phloxine B. This was not the case with protein–fed flies. The wasp Fopius arisanus (Sonan), one of C. capitata's primary natural enemies in Hawaii, would not consume protein baits. Our studies suggest that spinosad or phloxine B, with low contact toxicity, mixed with protein baits offers a more environmentally friendly choice for control of C. capitata and conservation of F. arisanus, whereby the nontarget effects of broad spectrum contact poisons such as malathion can be avoided. Presumably, due to greater selectivity with spinosad and phloxine B bait treatments, the host would be killed, but not the natural enemy.     

Reversible changes in the testes and epididymides of dog treated with alpha-chlorohydrin.

1. Chronic administration of alpha-chlorohydrin (8 mg/kg body wt for 30 days) caused lesions in the testis of dog. The changes in the germ cells were degenerative. The seminiferous tubule and Leydig cell nuclear diameter were reduced. 2. Epididymal cell height was greatly reduced and the stereocilia had disappeared completely. The lumen was devoid of spermatozoa. 3. Alpha-chlorohydrin administration inhibited the RNA and sialic acid contents in the testes and epididymides of dog. Total cholesterol and lipids/g of testes were increased significantly after alpha-chlorohydrin administration. 4. These effects were reversible. Repopulation of testis tubules occurred following a period of 100 days recovery in dog. Numerous spermatogonia and sperm develop and traverse the epididymides. The RNA, sialic acid, cholesterol and total lipids of testes and epididymides returned to subnormal levels. 5. The possibility of using alpha-chlorohydrin as male contraception is indicated.     

Effect of physiological (in lamb) or drug-induced (in adult) immaturity of ram spermatozoa on seminal plasma alpha-glucosidase activity

We have been able to collect ejaculates from four pre-pubertal Finnish Landrace and Suffolk lambs. Respective seminal plasma alpha-glucosidase specific activity was low (less than 0.3 mU/mg) whatever the season of observation. At puberty, it reached a level higher than 1 mU/mg as observed in adult rams. Administration of alpha-chlorohydrin to 14 adult rams (25 mg/kg/day during 25 days) led to the appearance of immature sperm. Seminal plasma alpha-glucosidase activity dropped from 1.5 to 0.5 mU/mg in both breeds, while fructose was raised from 2 to 6 mg/ml. L-carnitine and blood plasma testosterone remained unchanged during treatment. Semen characteristics appeared normal one month after the end of treatment when fructose concentration decreased simultaneously and enzymatic activity increased during two months to normal levels. The present findings suggest that seminal plasma alpha-glucosidase may be considered as a useful epididymal marker in ram.     

The effects of alpha-chlorohydrin on the composition of rat and rabbit epididymal plasma: a possible explanation of species difference.

The relationship between the antifertility effect of alpha-chlorohydrin and changes in composition of luminal plasma from the cauda epididymidis of rats and rabbits has been investigated. At each dose regimen studied, the fertilizing capacity of rats treated with alpha-chlorohydrin was reduced to zero. The levels of sodium, potassium, glycerylphosphorylcholine (GPC), acid phosphatase and alkaline phosphatase in epididymal plasma were not markedly affected by drug treatment. The most noticeable change was a considerable increase in the concentration of lactic dehydrogenase (LDH) at all dose levels and of glutamic-oxaloacetic transaminase (GOT) after 7 days of treatment with 8 and 16 mg/kg. The effect of cold shock on the composition of epididymal plasma showed that LDH and GOT are, at least in part, derived from spermatozoa. In contrast, alpha-chlorohydrin did not have an antifertility action in the rabbit, and the only notable change in the compositon of epididymal plasma was an increase in the level of GPC. These results provide evidence that, in the rat, alpha-chlorohydrin or a metabolite primarily exerts its antifertility effect by a direct action on the spermatozoa, whilst in the rabbit a barrier may exist to the entrance of the drug into the lumen of the epididymal duct.     

Levamisole can reduce bait monopolization in wild red foxes Vulpes vulpes

1. Baits are used worldwide to deliver vaccines, contraceptives and poison to wild animal species. In carnivores, multiple bait uptake and bait monopolization by dominant individuals may reduce baiting effectiveness. This study investigated whether a conditioned‐taste‐aversion agent, levamisole, can be used to decrease bait consumption by individual wild foxes Vulpes vulpes. 2. The results indicated that after consuming levamisole‐treated baits, foxes avoided eating treated baits but consumed untreated baits. We concluded that the reduction in bait consumption was achieved through learned aversion to levamisole rather than via conditioned‐taste‐aversion to baits. Adding levamisole to baits could potentially be used to reduce bait monopolization by individual wild foxes.     

Comparisons of toxic baits for controlling the cockroach, Blattella germanica: attractiveness and feeding stimulation

Female German cockroaches, Blattella germanica (L.) (Dictyoptera: Blattellidae) and nymphs (stages 1, 3 and 6) were used to test the attractiveness and the feeding stimulation of several commercial gel formulations of insecticide food baits in laboratory binary choice tests. The four toxic gel baits tested were: 'Avert' (0.05% abamectin=avermectin B1), 'Drax' (33.3% boric acid), 'Goliath' (0.05% fipronil) and 'Maxforce' (2.15% hydramethylnon). The attractiveness of a bait was estimated by the number of cockroaches that chose it first, and by their tendency to change to it secondarily. Feeding stimulation was estimated by the mean duration of feeding bouts and total duration of food intake. Variability of these factors was assessed in relation to age of cockroaches and to age of baits. With a few exceptions, cockroach age did not affect performance in any of these tests. Attractiveness to B. germanica ranked 'Goliath' gel higher than 'Avert', 'Drax' and 'Maxforce' gels, whether or not the active ingredient fipronil was present in 'Goliath' gel. Feeding stimulation ranked 'Avert' and 'Maxforce' gels higher than 'Goliath' gel, and 'Drax' gel was inferior. With ageing up to 3 months, the feeding stimulation power of 'Goliath' and 'Maxforce' gels increased, whereas that of 'Avert' fluctuated. Assuming that all types of bait effectively kill cockroaches once ingested, these results illustrate the importance of behavioural observations on bait efficiency and show that ranking of these different food baits varies in relation to the parameter analysed.     

四种常用抗凝血灭鼠剂对两种家栖鼠实验室药效比较

比较了几种抗凝血灭鼠剂对家栖鼠的毒效。以常规浓度（溴敌隆０．００５％,杀鼠迷、杀鼠灵和敌鼠钠０．０２５％）的毒饵,对靶标鼠进行单笼饲养无选择和有选择以及围栏群养有选择摄食试验,用毒杀率和摄食系数评价毒效和适口性。结果表明：⑴实验鼠单笼饲养试验：溴敌隆和杀鼠迷对大白鼠适口性好,毒杀率高,敌鼠钠适口性差;对小白鼠的毒效和适口性,溴敌隆最好,敌鼠钠最差;⑵三省四地区的褐家鼠单笼饲养无选择试验,溴敌隆、杀     

The influence of density on frequency-dependent food selection: a comparison of four experiments with wild birds

We compare the results of four experiments, conducted at different times and with different protocols, that explored the relationship between frequency-dependent selection and prey density in wild birds feeding on artificial populations of coloured baits. One (experiment 4) used pastry baits that differed only in the presence or absence of a red stripe, and this experiment provided no evidence for any kind of selective behaviour. The other three experiments used green and brown baits, and they all provided evidence for a trend towards increasing anti-apostatic selection with high densities (>100 baits m^–2). However, one of these (experiment 3) provided no evidence for frequency-dependent selection at low densities (0.5–20 baits m^–2), while the other two experiments concurred in suggesting a trend towards increasing apostatic selection with low densities (down to 2 baits m^–2). Together, these experiments both support and qualify the published findings of experiment 1 that frequency- dependent selection by wild birds on bait populations is modified by density. Experiment 4 indicates that frequency-dependent selection may break down entirely if bait types are too similar, while experiment 3 indicates that some details of this trend with density will depend either on the protocol used or on exogenous changes in the birds’ feeding behaviour. Received: 1 September 1999 / Accepted: 22 March 2000     

Differential consumption of baits by pest blattid and blattellid cockroaches and resulting direct and secondary effects

Consumption was measured of three commercially available cockroach gel baits (0.01 and 0.05% fipronil and 0.6% indoxacarb) by two pest blattellid (German cockroach, Blattella germanica L., and brownbanded cockroach, Supella longipalpa Fabricius) and three pest blattid [oriental cockroach, Blatta orientalis L., American cockroach, Periplaneta americana L., and smokybrown cockroach, Periplaneta fuliginosa (Serville)] species (Dictyoptera), and direct and secondary effects were quantified. All three baits were greatly preferred for consumption over dog food; however, virtually all consumption (ca. 98%) by pest blattids was gel baits containing sugar feeding stimulants and water. Pest blattid greater preference for gel baits was probably due to their greater need for nutrients in baits due to their greater cuticular water permeability and higher metabolism than the pest blattellids. Brownbanded cockroaches had lowest percentage gel bait selection. Pest blattellids consumed greater amounts of bait per g body weight than pest blattids. Cockroaches consumed more active ingredient than needed to cause mortality; however, based on bait consumption, a 30‐g tube of gel bait potentially killed from 394 to 6 966 adult cockroaches, depending on species. Mortality for all cockroach species was faster for adults (≥3 days) than for nymphs (≥7 days); however, most brownbanded cockroaches exposed to indoxacarb survived despite consuming 1.5‐ to >3‐fold more than other baits, suggesting low enzyme production by brownbanded cockroaches and consequently lower conversion of indoxacarb into its toxic form. Besides direct mortality, German cockroaches died from indirect effects: exposure to debris from other cockroaches that had direct access to the gel baits or bait contact without ingestion. Although maximization of bait consumption is important, factors that enhance secondary mortality and contact toxicity should also be considered.     

Comparative effect of three rodenticides warfarin,bromadiolone and brodifacoum on the Indian field mouse,Mus booduga gray

Three anticoagulant rodenticides, warfarin, bromadiolone and brodifacoum, were evaluated in the laboratory for their activity against the Indian field mouse, Mus booduga. In oral intubation studies M. booduga was found to be more susceptible to bromadiolone and brodifacoum than warfarin. Feeding studies with 0.005% bromadiolone and brodifacoum baits produced 83% mortality after a single day's feeding while a similar mortality was achieved with 0.025% warfarin only after 6 days of consecutive feeding. The anticoagulant baits were less palatable than the plain (unpoisoned) bait. Laboratory feeding tests confirmed that 0.005% of the active ingredient would be an effective bait concentration for field use of both bromadiolone and brodifacoum. The single-feed potency of bromadiolone and brodifacoum indicate that these rodenticides may be more effective and economical than warfarin in the field.     

Evaluating and predicting risk to a large reptile (Varanus varius) from feral cat baiting protocols

Control of introduced predators to mitigate biodiversity impacts is a pressing conservation challenge. Across Australia feral cats (Felis catus) are a major threat to terrestrial biodiversity. Currently feral cat control is hindered by the limited utility of existing predator baiting methods. Further proposed control methods include use of the novel poison para-aminopropiophenone (PAPP) which may present a hazard to some native animal populations. Here we used experimental and predictive approaches to evaluate feral cat bait take by a large native Australian predatory reptile the Lace monitor (Varanus varius). These lizards would be expected to readily detect, ingest and consume a lethal dose (depending on toxin) from surface-laid baits intended for feral cat control if a precautionary approach was not adopted when baiting. We modelled V. varius bait take using experimental and predictive biophysical modelling approaches to evaluate temporal effects of climate variables on V. varius activity and hence potential for bait removal. Finally we conducted a pre-PAPP baiting site occupancy assessment of V. varius within Wilson Promontory National Park (WPNP) to provide a basis for monitoring any longer term population effects of cat baiting. V. varius removed 7 % of deployed baits from 73 % of bait stations across another study area in Far Eastern Victoria. Daily bait removal was positively correlated with maximum temperature and solar radiation. Biophysical modelling for Far Eastern Victoria predicted that maximum temperatures <19.5 °C prevented V. varius activity and hence opportunity for bait removal. V. varius in WPNP was undetectable suggesting aerial baiting posed limited hazard to this species at this location. Depending how climate influences annual activity patterns and the specific poison, surface-laid baits could pose a significant mortality risk to V. varius. However, use of biophysical models to predict periods of V. varius inactivity may provide a novel means to reduce non-target bait take by this predator.     

Bait consumption and residual concentrations of diphacinone in the Wellington tree weta (

To investigate the potential for mortality or sublethal effects in the tree weta (Hemideina crassidens) as the result of exposure to baits used for rodent control, and the potential secondary hazard to non-target species, captive weta were offered Ditrac® wax block bait containing the anticoagulant diphacinone. Bait consumption was recorded daily for the first week and then weekly. Weta were sampled in groups of four following 1, 4, 8, 6, 3, and 64 days of exposure to bait and analysed to determine the concentration of diphacinone residues in their bodies. Any changes in feeding behaviour, survival, and bodyweight were recorded. Weta found Ditrac wax block baits palatable even in the presence of natural plant food, showing steady consumption of bait over time. No mortality or weight loss was attributable to the intake of Ditrac bait. All weta that ate bait had detectable diphacinone in their bodies, but did not accumulate diphacinone, i.e. whole-body concentrations did not increase with the amount of diphacinone bait eaten over time. Field use of diphacinone bait is likely to present a low risk of mortality to weta, but the risk posed by secondary diphacinone exposure to non-target species that eat weta requires further investigation.     

Elimination of subterranean termite (Isoptera: Rhinotermitidae) colonies using a refined cellulose bait matrix containing noviflumuron when monitored and replenished quarterly

Using a quarterly (3-mo) monitoring and bait-replenishment interval, 122 subterranean termite colonies throughout the United States were baited with a refined cellulose bait matrix containing 0.5% noviflumuron. All colonies were eliminated in less than 1 yr after initiation of baiting as determined by long-term monitoring and genetic markers. Sixty-three percent of the colonies were eliminated during the first quarter after the initiation of baiting and 77% of colonies were eliminated after consuming two bait tubes or less. This suggests that a single baiting cycle and bait installed in response to a single active monitoring device were sufficient to eliminate the majority of colonies. Although termites temporarily abandoned stations after depleting bait, workers resumed feeding when baits were replenished. Colonies that consumed large amounts of bait before elimination foraged into multiple stations, thus allowing adequate amounts of bait to sustain feeding. The time to eliminate termite colonies with bait replenished quarterly was similar to that previously reported for laminated cellulose bait replenished monthly. Our data support the conclusion that extending the bait replenishment interval from monthly to quarterly for bait tubes with refined cellulose containing 0.5% noviflumuron did not adversely impact colony elimination.