Preference of some food types and their efficacy as poisoned baits ( zinc phosphide ) against fruit bat under laboratory conditions

In laboratory, some food of fruits, vegetables and field crops were tested under nonand free choice to determine the food palatability and preference for the Egyptian fruit bat, Rousettus aegyptiacus. This is prefatorily to be used as poisoned bait. The obtained results elucidate that generally, under non-choice field crops record, the low palatable was the wheat (the consumption was zero %). While the fruits palatability ranked firstly then vegetables. The average percent of daily consumption of each food group field crops, vegetables and fruits were 10, 30 and 58% respectively. Bats preferred guava, apple, date, tomato and carrot respectively. The toxic effect of compressed date of 5.0, 1, 1.5 and 0.2% zinc phosphide caused mortality ratios of 30, 60, 100 and 100% to each concentration respectively. On the other hand, the bait consumption was reduced with increased concentration. So, Apple and Guava used as bait with zinc phosphide rodenticide 0.5, 1.0 and 1.5% to enhance the bait consumption and the results showed that the apple bait was more effective against fruit bat compared with guava and compressed date baits. Also, the concentration of 1.0% zinc phosphide with apple caused 100% mortality compared with the same concentration of guava and compressed date where the mortality was 70 and 60% and the average bait consumption was 15.3, 20.4 and 10.9g respectively.


INTRODUCTION
Bats have the highest number of mammals after rodents (approximately 925 species).Also, among living vertebrates, bats and birds are unique in their ability to fly.In some ways bats, the nocturnal equivalents of birds, have successfully colonized almost every continental region on earth except Antarctica.Generally, bats exhibit a dietary diversity as, fruits, leaves, flowers, nectar, pollen, insects, fish, blood and other vertebrates.
The Egyptian fruit bat, Rousettus aegyptiacus (Order: Chiroptera, family: Pteropodidae) is considered an agricultural pest (Kock, 2001).Tomas et al. (1984) observed that in most cases the fruit bat caused a great damage on vegetables and fruits.Palaeotropical bats (Pteropodidae) ingest up to 2.5 times their body mass in fruits nightly.On a mass-specific basis, this is about double the amount reported for neotropical fruits bats (Phyllostomidae).Also, the Egyptian fruit bat Rousettus aegyptiacus is regarded as a pest for agriculture in Israel and feed mainly on fruits sometimes leaves and pollen are also eaten.Persimmons, loquats, figs and dates fruit constitute 15% of the bats diet (Korine et al., 1998).Other researchers reported that bats feed wide kinds of plant (54 plant species) according to plant availability and quality, season also, need of energy and protein (Feldhamer et al., 1995;Kunz and Diaz, 1995;Bizerril and Raw, 1998;Luft et al., 2003).Many researchers and farmers are painstaking to protect the plant farms of vegetables and fruits against attacks of fruit bats.In the nest bat, controlling is made by burning sulphur (30g) with peprik (1g) per m3.Another method used silky net for 7 days (Eissa, 2007).Sometimes poisoned bait was used as date with 3% zinc phosphide bait.This work aims to determine the preference diet from tested vegetable, fruit or field crops to be used as bait with best effectiveness of zinc phosphide concentration against fruit bat Rousettus aegyptiacus.

Bats:
The fruit bats, Rousettus aegyptiacus, were trapped from El-Soultan Hassan regions Cairo Governorate by using mist net which set at the sunset in the bat going place.In laboratory, collected bats were weighted and sex determined.Animals were retained individually in wire mash hold cages (90 x 50 x 50 cm).During the acclimation period animals had access to water and guava fruits for 2 weeks.

Chemical and baits:
Technical grade zinc phosphide (94% active ingredient) was obtained from "Kz pesticide company, Egypt" then different baits were prepared.Firstly, poisoned bait of compressed date 0.5, 1, 1.5 and 2g zinc phosphide weighed and mixed with 100g of compressed dates then douched good and balled (each ball 20g).The second type of bait is prepared from the preferred fruits: guava and apple which were tested previously.The fruit were slices (5x2x2cm) and left in laboratory conditions up to have dry surface (3 hours); 0.5, 1 and 1.5g of zinc phosphide mixed with 10g of flour then mixed with fruit slices.

Procedure: Food Palatability:
Three hundred grams of vegetable types: Tomato, Cucumber, Carrot, Eggplant and Squash; fruit types: guava, Apple, Date palm, Fig and Pear; and field crops: Wheat, Maize, Sorghum, Sunflowers and Sugar cane were used as food in the suspended shape.Groups of five individuals were used to each food type.Animals were daily supplied by water and the remaining food weighted and replaced with the same fresh food for four days.The average food and relative consumption were determined.

Food Preference:
The highest food palatable according to the previous test, Date, Guava, Apple, Tomato and Carrot were used under free-choice.Two hundred grams from each food were presented to five individually caged bats then the consumed amount of food was daily calculated and replaced by fresh for four successive days.The position of suspended food was changed daily to avoid location preference.Acceptance percentages were estimated according to the following formula (Buckle and Smith, 1994): Av. consumed of tested food (g) X 100 Av.Total consumed (g)

Toxicity Test:
Four groups (of 10 animals) of bats were used per each concentration of compressed date poisoned baits (0.5, 1, 1.5 and 2% zinc phosphide).Five balls of bait (each ball 20 gr) were suspended in cage ceiling by rope.After one day the poisoned baits were removed and replaced by fresh diet and water.The consumed bait was calculated and dead animals were recorded during three days of treatment.
Another experiment used the preferred fruits, Apple and Guava, as a bait of 0.5, 1 and 1.5% zinc phosphide.Groups of 30 animals each were used.Each group was divided into three sub-groups of 10 animals per each concentration.The poisoned bait slices were suspended in cage for one day, thereafter the poisoned bait was removed and replaced by fresh fruit.The bait consumption and dead animals were recorded during three days of treatment.

Food palatability and preferring:
Under laboratory conditions, types of food were tested to determine the palatability and preferring among different food types of fruit, vegetables and field crops.
Date in table (1) showed that under non-choice among the vegetable types tested, bats consumed a large amount of tomato (average 98.6 g) daily.But, the average consumption was 66.3g of carrot, 36.9g of cucumber and 32.9g of squash.Also, egg-plant recorded the lowest consumption (27.8g).On the other hand, the relative consumption showed that carrot comes in the first palatable (0.67%), then the remaining vegetables which did not reach to the half of tomato consumption: cucumber 0.39%, squash 0.32% and egg-plant 0.28%.The relative consumption after guava ranked as follows: Apple 0.96%, Fig. 0.87%, Pear 0.8% and Date 0.78%.The consumption of field crops is reported in table (3): bats consumed 37.7 g of Sun Flower, 17.8 of Sugar cane, 22.2 g of Maize and 12.3 g of Sorghum.While, wheat consumption was zero, the relative consumption showed that wheat was unplatable.Sun Flower and Maize 0.58, were highly platable compared with Sugar Cane 0.47, and Sorghem 0.33, respectively.Regarding to Fig.
(1), it is observed that bats preferred fruits more than vegetables and field crops where the average total consumption of different groups were (fruits 484.3g, vegetables 262.6g) but field crops come at last with the consumption of 90g.Under free-choice the food preference among the highest palatable food types, date, guava, apple, tomato, and carrot were determined and the obtained data in table (4) revealed that the bats consumed in average 50.4g,42.7g, 12.3g, 12.3g and 5.9g daily from tested food types respectively.Guava is more pereferred than apple with acceptance of 41.08 and 34.8% then date and tomato each of 10.02% and carrot recorded the minimal acceptance 4.07%.
Generally, most tested field crops were low palatable to bat except sunflower and sugar cane.Bats preferred fruits and consumed large amounts of it compared with vegetables.This may be because fruits contain sugars and proteins which supply bat with energy, (Tomas et al., 1984).Tomas et al. (1984) found that male bat consumed a large amount of food compared with female bat.Both sexes preferred fruits more  Toxicity of zinc phosphide baits against fruit bat: Four concentrations of zinc phosphide 0.5, 0.1, 1.5, and 2% were mixed with compressed date caused different mortality percentages in bats.Table (5) showed that concentration of 0.5% killed 30% of treated animals; the mean consumed bait was 11.5 g., while 60% from treated animals died after consuming 10.9 g of poisoned bait of 0.1%.Other concentrations: 1.5% and 2% caused the same mortality percentage (100%); the consumed bait was 7.7 and 7.3g to each concentration respectively.Fig.
(3) elucidates that the mortality percentage increased with zinc phosphide concentration increase with reduction of the amount of bait consumption.In evasion to enhancing the mortality percentage with low concentration of zinc phosphide by increasing the lethal dose intake of the preferred fruit (Guava and Apple) were used as bait compared with compressed date.Data in table (6) shows that apple baits 0.5, 1 and 1.5% zinc phosphide cause 70, 100 and 100% mortality and the bait consumption were 17.5, 15.3 and 15.5g., while guava bait of the same concentrations cause 40, 70 and 90% mortality of treated animals and the bait intake were 20.4,20.4 and 18.7 g respectively.Comparison with compressed date poisoned bait consumption and the mortality percentage increased with using guava or apple compared with compressed date bait.The apple poisoned bait caused highly percentage of bats mortality more than guava bait in spite of reducing the apple bait intake.This observation may be due to guava water content which attributed to loss of phosphine gas from zinc phosphide and reduced the toxic effect.By using the biological methods, Rizk (2000) found that the poisoned bait of zinc phosphide 2.5% lost 20% and 50% of its effectiveness when exposed to 80% R.H for 2 and 7 days, respectively.
non-and free-choice methods.The obtained results may explain the bats distribution and population density in plantation areas according to type of plant.

Table 1 :
Food Palatability of fruit bat R. aegyptiacus to vegetables under non-choice methods.

Table 2 :
Food palatability of fruit bat R. aegyptiacus to fruits under non-choice methods

Table ( 3
): Food palatability of fruit bat R. aegyptiacus to field crops under non-choice methods.
Fig. 1: Food consumption of different food groups by fruit bat R. aegyptiacus under non-choice method.Fig. 2: Food preference of different food types to fruit bat R. aegyptiacus under free choice method.

Table 4 :
Food preference of fruit bat R. aegyptiacus to different food types under free choice methods.

Table ( 5
): Toxicity of different concentrations of zinc phosphide compressed date bait against R. aegyptiacus under laboratory conditions.

Table 6 :
Effect of preferred food as a poisoned bait zinc phosphide against R. aegyptiacus under laboratory conditions.