Arama motoru botlarının etiket girmesini engellemek ?

</div>
   <div class="boxestext">
    <form action="<?php echo $siteurl; ?>/index.php?action=search" method="POST">
    <input type="text" name="t" maxlength="25" size="20"><br>
    <input type="hidden" name="botmusun"  value="evet">
    <input type="submit" value="Ara">
    </form>
   </div>
 </div>

$kelime = mysql_real_escape_string($searchTerm);
        $sonuc = mysql_query("Select Count(kelime) From arananlar where kelime='$kelime'");
        $sayi = mysql_result($sonuc,0);
        $kelime=araz2($kelime);

        if($sayi ==0){
        if ($_POST[botmusun] != "evet") { 

                @@mysql_query("Insert Into arananlar (kno, kelime) Values ('', '$kelime')");
        }
}