Ecology of Aphidophaga

International symposia on the research into behaviour and ecology of aphidophagous insects

ECOLOGY OF APHIDOPHAGA - EARLY HISTORY

After the era of great hopes in insecticides, the 50s brought a return to the interest in entomophagous insects. The authors of the concept of integrated control (based on the research on aphid pests on alfalfa and published in California in 1959; see Ken Hagen's bibliography), Ray F. Smith, Vernon M. Stern, Robert van den Bosch and Kenneth Hagen, realized the fundamental contrast between the impact of coccidophagous and aphidophagous insects on the population dynamics of their preys. It has become clear that the expectations arisen from the success with the introduction of Rodolia cardinalis did not take into consideration the principal difference in the prey-predator relation between coccidophagous and aphidophagous coccinellids. This difference has been neglected, although it has long been well known that, among several important factors (e.g. synchronisation), one is decisive for the prey-predator relation: The ratio between the annual number of generations of the predator and its prey. In case of R. cardinalis and Icerya purchasi, the ratio is about 1 : 3 in favour of the predator: R. cardinalis has roughly 3 generations to one of the prey. ( In citrus groves in Israel and California, the ratio is similar: the scale insect has 4 gen/yr, the coccinellid 12 gen/yr.) In contrast, the aphid eating ladybird Hippodamia quinquesignata is usually bivoltine, while the aphid Therioaphis trifolii may have up to 35 gen/yr in California. Even if we calculated with an unusually high number of 4 gen/yr for the coccinellid and only 20 gen/yr for the prey, the ratio would be 5:1 in favour of the aphid.

Together with colleagues from Britain (Michael Way, John Banks and Helmut van Emden), France (Lucien Bonnemaison and Gabriel Iperti), and Germany (Siegfried Bombosch), we all shared the view that the case of aphids, particularly on annual crops, would need a long and very detailed study of ecology and behaviour of their natural enemies. As it was hoped that international exchange of experience and views could foster the progress in the field, several people adviced to organise a meeting. The European specialists were invited by Bombosch to Goettingen in March 1965 , and they decided there to take part in a symposium "Ecology of Aphidophagous Insects" in Czechoslovakia, that was intended to have a worldwide scope, in particular involving also the researchers from California and Canada. Our country was chosen for two reasons. (1) At that time, it was difficult for scientists from the "eastern camp" to travel to the "west", but relatively easy for the colleagues from the "west" to visit the "eastern" countries. In the relatively liberal period in mid 60s an "opening to the world" even took place and the idea of an international meeting in Czechoslovakia was supported. (2) In the Academy of Sciences in Prague, there was an active team of 4 young workers studying aphids (J. Holman), coccinellids (I. Hodek), aphid parasites (P. Stary) and chrysopids (J. Zeleny). Their earliest paper appeared in 1954 and a booklet "Natural Enemies of Aphis fabae" was in press. A specialist on syrphids and Heteroptera, P. Stys from the Charles University also joined the team.

The symposium took place at Liblice, a small castle then belonging to the Academy, and both the lectures and discussion were simultaneously translated from and to four languages!!! There were 56 participants from 17 foreign countries (plus 16 from Czechoslovakia). Several first-rank specialists arrived, who unfortunately are no longer among us, and some of them have become almost mythical personalities (Plate 1): L. Bonnemaison and J.P. Lyon (France), D. Hille Ris Lambers and H.J. de Fluiter (The Netherlands), B. Galecka (Poland), J. Banks and J.S. Kennedy (UK), R.v.d. Bosch and K. Hagen (USA), V.V. Yakhontov (USSR-Uzbekistan). Apart from those deceased colleagues mentioned above, the meeting was attended also by other leading specialists who have since retired, such as Hew Chiang (USA) or Gabriel Iperti (France). Others are still active, although they are emeriti (Tony Dixon, Helmut van Emden, Michael Way from UK). As a student with Michael Way, Roger Blackman, a recent leading aphidologist, joined us as well. The symposium was a success and the Proceedings (1966; all lectures translated to English) have since been often cited. I would like to believe that this event - similarly to the subsequent meetings - helped the progress in the field. To show that the comments expressed almost 40 years ago may still be useful, I am joining copies of several pages by Ray F. Smith.

In 1965, some promises were made during the farewell party and thus we hoped to meet again after a short period again. However, nothing happened - for a long period of 19 years!

Three years after the symposium, our country went through great and unpleasant changes - after the "friendly help" of Soviet tanks. For several years I had thus other problems than to remind colleagues of their promises. On the contrary, around 1980 several of them asked me again to convene the second meeting, which I did. In the meantime our Institute was transferred from Prague to Ceske Budejovice and thus the meeting was held in southern Bohemia about halfway between the two towns, in a hotel at Zvikovske Podhradi, near a gothic castle (logo of the meeting) (Plate 2). To provide an overview of further developments, two tables follow that summarize the participation and sites of the subsequent symposia and also bibliographic data on the Proceedings.

August 2004, I. Hodek