A mainstay of the Israeli kibbutz -- the teen-aged foreign volunteer worker who is willing to exchange long hours of unpaid farm labor for a brief socialist-Zionist experience -- may be an endangered species.

Israel's oldest kibbutz collective settlement, Deganya Aleph in the picturesque Galilee, has joined several other kibbutzes in ending the decades-old practice of accepting foreign volunteers -- many of them adventurous Gentiles -- to help with agricultural work.

The reason given by the leaders of the kibbutz is that the young foreigners have begun to dominate the social and cultural life of the Israeli children in the settlements and have made them forget the Zionist ideology that is the backbone of the kibbutz movement -- as well as intermarrying with them and taking them out of Israel.

Eitan Peretz, secretary of the Deganya kibbutz, said the backpacking foreign volunteers had also contributed to intermarriage between Jews and Gentiles. Many young kibbutz members, Peretz said, have been influenced by the comparatively freewheeling life style of the volunteers and had followed the foreign visitors to Australia, Europe and the United States for a more materialistic life.

Peretz said that he knew of eight kibbutz youths who had married volunteers and left Israel. He said that the collectives' members had voted to end the volunteer program in an effort to prevent further emigration.

"There is a general feeling that the day of the volunteer on the kibbutz is over," Peretz said. He said the collective's members would have to work harder without the volunteer help, but would feel more secure without the constant foreign influence on their children.

In a telephone interview, Peretz said the original idea of the volunteer program was to obtain useful and cheap labor, while at the same time hosting potential ambassadors of good will for Israel. But, he said, the "easygoing western life" of the volunteers proved to be "too high a price for us to pay."

Two other kibbutzes, Shaar Hagolan, in the Golan Heights, and Lehavot Habashan, also have decided not to accept foreign volunteers, and several other settlements were reported to be considering similar moves.

Shlomo Leshem, spokesman of Israel's United Kibbutz Movement, said in a telephone interview that the targets of the cutback are young backpackers who "follow the sun" through the Mediterranean and wind up during the growing season in Israel with less commitment to the kibbutz ideology than youths who join Jewish youth movements abroad and go to kibbutzes in organized groups. Leshem said that Israel's 280 kibbutzes have recruiting offices abroad to sign up volunteers in groups, who represent 60 percent of the foreign volunteers who come here each year.

Some kibbutzes "have decided not to accept any volunteers, and that is a decision that has to be decided by the members. But we will give preferential treatment to those who register abroad in groups," said Leshem, adding that the impact of Israel's ailing economy on the kibbutz movement would compel some settlements to continue accepting volunteer workers.