New Worlds: Ant, rodent behavior differs by country

Ant, rodent behavior dif

By JUDY SIEGEL-ITZKOVICH
cute lab rat 248.88 (photo credit: Joanna Servaes)
cute lab rat 248.88
(photo credit: Joanna Servaes)
Israelis are by experience and almost by nature more alert when they see a suspicious object. But now, University of Haifa scientists working in partnership with counterparts in Jordan have found that Israeli rodents - as well as some other species - are also more careful than those on the other side of the border. "The border line, which is only a demarcation on a map, cannot contain these species. But the line does affect humans and their impact on nature," says Dr. Uri Shanas of the university's department of environmental and evolutionary biology and its Oranim faculty of sciences and science education. The series of studies has examined a variety of reptile, mammal, beetle, spider and ant lion (a kind of large ant) species on either side of the border in the Arava. Shanas and research students Idan Shapira and Shacham Mitler set out to learn whether the border could cause differences between species, even though they share identical climate conditions. The first study inspected the reptile population and revealed that the number of reptiles is similar on both sides, but the variety in the sandy areas of Jordan is significantly higher than in the sands of Israel. A second study revealed that Israeli gerbils (desert rats) are more cautious than their Jordanian friends, while a third study showed that the tunnel-digging ant lion population in Israel is unmistakably larger than that in Jordan. According to the researchers, the differences between the two countries are primarily in the higher level of agriculture and greater number of farms in Israel as opposed to Jordan. Israeli fields on the border are visited by one of the most problematic of intruders, the red fox. On the Jordanian side, the red fox is far less common, so that Jordanian gerbils are more carefree. The higher reproduction rate of ant lions on Israel's side is related to the presence of the Dorcas gazelle. This animal serves as a kind of environmental engineer, as it breaks the earth's surface and enables ants to dig their tunnels. The Dorcas gazelle is protected in Israel, but is fair game in Jordan. "The current studies clearly display the influence that man has on nature - for better and worse," Shanas concludes. FRUITFUL THEORIES The mysterious death of honey bees has been confounding scientists and farmers, who worry about reduced pollination levels and fruit production. A recent study at Oregon State University has shown that native bumble bee species have consistently high pollination levels in red clover, and might be able to "cover" for their bee cousins. The findings, published inCrop Science, offer promise for the use of bumble bee pollinators as an alternative to the endangered European honey bees. Red clover, grown for forage and as a rotation crop to improve soil, is raised for seed in western Oregon's Willamette Valley. It will not produce seed without pollination, so growers typically place more than five European honey bee hives on each dunam. However, bee diseases, mites and colony collapse disorder have limited bee availability and resulted in higher costs for hive rentals. Worldwide, there are over 200 bumble bee species; some of which are known to pollinate red clover. While commercially reared bumble bees are available to growers elsewhere, they are considered an exotic species in Oregon and cannot be introduced into the state. This leaves Oregon growers dependent on naturally occurring populations of bumble bees as pollinators. The OSU scientists investigated native bumble bees in commercial red clover fields. Prior to bloom, researchers covered plants with mesh-screened cages. European honey bee hives were placed in some cages and nests of B. vosnesenskii (a native Oregon bumble bee) in others. Some cages were also left vacant. After bloom, seed yield was compared. There were no differences in seed yield in cages with bumble bees compared to honey bees, the study revealed "To sustain these high yields in Oregon, we must conserve the habitat of the bees, use pesticides judiciously, and provide floral resources prior to red clover bloom," concluded OSU entomologist Sujaya Rao, one of the researchers.