The pacú (Colossoma macropomum) is an important commercial and subsistence fish resource in Amazonia. Pacú depend on the unique hydrology of the Amazon Basin, in particular the occurrence of annual floods, and require a healthy and intact flooded forest ( várzea) for food resources during the wet season. From March to December of 1999, 128 pacú were collected and aged ( by means of otoliths) from subsistence harvests in the town of Bella Vista, located at the juncture of the San Martín and Blanco rivers in northeastern Bolivia. The age structure of the harvested population implied a healthy and lightly exploited stock and suggested that sustainable harvest is occurring. Population parameters at our site were similar to the neighboring, lightly exploited Mamoré River system but differed slightly from heavily exploited stocks in Brazil. Pacú harvested near Bella Vista are of special concern because of poaching and the increasing regional demand for fish, and because the várzea habitat on which the pacú depends is currently threatened by cattle production, development activities, and land‐tenure conflicts. As development increases throughout Amazonia, careful management of pacú fisheries and the flooded forest on which they depend will be of critical importance.

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A number of research institutions and both local and international agencles in Latin America are using biotechnology as part of an effort to enhance agricultural productivity. However, it is very much an open question as to whether all of these various organizations can provide the best means of realizing this goal. Latin American countries vary dramatically in their knowledge base and current use of modern biotechnology. Thus, while some countries lack the ability to develop, or possibly even implement, many aspects of modern biotechnology, others are quite advanced in this regard. This review provides a somewhat selective overview of current research in the area of agricultural biotechnology in Mexico, Costa Rica and Ecuador, with emphasis on how the existing agencies and institutions have responded to the challenge of biotechnology. In addition, general strategies for the development of agricultural biotechnology in these countries are presented and discussed.

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The pine‐gallmidges and their economic significance in Lower Saxony From 1981 till 1984 there were outbreaks of the gallmidges Thecodiplosis brachyntera and Contarinia baeri in Lower Saxony, especially in the eastern parts. In two research areas the attack was low to medium in 1983 and low in 1984. In galls of T. brachyntera only one larva per gall was found, while up to 17 larvae of C. baeri lived in one pair of needles. Until August mortality of both species reached 90%. Needles attacked by T. brachyntera grew to only 30–40% of the length of healthy needles. Needle shortening by C. baeri amounted up to 88%. C. baeri preferred the terminal parts of trees, whereas T. brachyntera showed no preference. Especially the highest trees of the research area were attacked by C. baeri. Depending on the intensity of attack in 1983 the sprouts from 1984 were shortened. It was found by a questionaire sent to the state forest districts in Lower Saxony, that a. the centres of attack lay in the eastern part of Lower Saxony, b. C. baeri was more frequent than T. brachyntera (80% to 12%), c. the attack declined from 1983 to 1984, d. 10–20 years old stands were mostly attacked, e. stands with relatively better supply of water and nutrients were preferred. From 1983 to 1984 the infestation strongly decreased and it is assumed that the gallmidge outbreak is breaking down. Zusammenfassung In den Jahren 1981 bis 1984 fand vor allem im niedersächsischen Pleistozän eine als „mittelstark” eingestufte Gradation der Kieferngallmücken T. brachyntera und C. baeri statt. Auf zwei ausgewählten Versuchsflächen konnte der Gallmückenbefall 1983 als schwach bis mittel und 1984 als schwach eingestuft werden. Bei T. brachyntera wurde durchschnittlich nur eine Larve pro Galle gefunden. Ca. 10 % der Gallen waren bereits im Sommer von den noch nicht ausgewachsenen Larven verlassen worden. Bei C. baeri wurden bis zu 17 Larven pro Nadelpaar nachgewiesen. Bei beiden Gallmückenarten konnte eine hohe Mortalität noch unbekannter Ursache beobachtet werden, die Ende August bereits ca. 90 % der Gallmückenpopulation erfaßt hatte. Die Länge der von T. brachyntera befallenen Nadeln betrug nur 30‐40 % der Länge gesunder Nadeln. Bei C. baeri war eine schwache Nadelverkürzung (88 % der Länge gesunder Nadeln) nachweisbar. Die Terminaltriebe und besonders ihre oberen Hälften waren deutlich stärker befallen als die unteren Triebquirle. Während C. baeri besonders die Terminalpartien der Bäume für ihre Entwicklung bevorzugte, konnte bei T. brachyntera kein schwerpunktmäßiger Befall in irgendeiner Baumzone festgestellt werden. Innerhalb der Versuchsflächen waren die höchsten Bäume und die Parzellenränder am stärksten befallen. In Abhängigkeit von der Befallsstärke 1983 und vom Alter der Bäume blieben die Maitriebquirle 1984 z. T. stark verkürzt. Eine Umfrage bei den Staatlichen Forstämtern in Niedersachsen ergab, daß a. die Schwerpunkte des Befalls im östlichen Niedersachsen lagen, ‐ b. C. baeri häufiger war als T. brachyntera (88 % gegenüber 12 %), ‐ c. der ...