1./ 1958-59: USA
     University of Wisconsin, California and Louisiana:
     Practical beekeeping in commercial apiaries.
     Instrumental insemination of bees.
     Prof. dr  C. Farrar, Prof. dr H. Laidlaw  
     (1 year)

2./ 1967-68: Brazil
     University of Sao Paulo in Riberao Preto:
      Investigation on diploid drones of African bees
     Prof. dr W. Kerr  
     (7 months)

3./ 1971: Fed. Rep. of Germany
     Frankfurt am Main University,Institut fur Bienenkunde,
     Oberursel: Investigation on reproduction of European
     and Indian bees - Apis cerana
     Prof. dr F. Ruttner
     (3 months).

4./ 1972: Norway
     Agriculture University in As, Beekeeping Institute in
     Asker: Investigation on bee breeding
     Dr Lunder
     (3 months).

5./ 1973: Australia
     Waite Agricultural Institute in Adelaide: Studies on
      honey bee sanctuary on Kangaroo Island
      Prof. dr K. Doull
      (3 months).

6./ 1974: India
     Central Bee Research Institute in Poona: Investigation
     on Indian bees (7 months)

7./ 992: China
     Institute of Apicultural Research, Chinese Academy of
     Agricultural Science, Bijing: Investigation on biology
     and control of Tropilaelaps clareae. (2 months)

8./ 1992: Thailand
    Chulalongkorn University, Bee Biology Research Unit,
     Bangkok: Investigation on Asian honey bees.
     Prof. dr S. Wongsiri
     (1.5 months).

9./ 1993: China
      Institute of Apicultural Research, Chinese Academy of
      Agricultural Science, Bijing: Investigation on biology
      and control of Tropilaelaps clareae. (1 month).

10./ 1995 Malezja
       Agricultural Research Station, Tenom, Borneo:
       Investigation on body color of Apis koschevnikovi.
       Dr Tingek
       (1 week).

12./ 1999/2000 Nepal
       Dabur Apicultural Center
       Investigation on relationship between Apis dorsata and Apis mellifera
       (7 months).

13./ 2000 Malta
       Investigations on Apis mellifera ruttneri  
       Mrs Marica Gato  
      (2 weeks)

14./ 2002 India  
       Bangalore University, Prof. dr C. C. Reddy, dr V. Sivaram  
       and Agricultural University, Bangalore Prof. dr G. Gowda  
       Investigations on Apis dorsata and A. florea  
       (1 month)

15./ 2004. PHILIPPINES  
      Los Baños 20. 02 - 10. 03 ,
       Investigation on defence behaviour of Apis dorsata breviligula
       Prof. dr C. Cervancia

16./ 2005. INDIA
       Bangalore13 Nov - 5 Dec  
       Investigation on drone flights of Apis dorsata.