Life table data for Aphis gossypii Glover (Homoptera: Aphididae), an important pest in glasshouse cucumber crops, were studied at 20, 25 and 30 °C on two cucumber cultivars (Cucumis sativus L.) in controlled climate cabinets. The development time on the cucumber cv. ‘Sporu’ ranged from 4.8 days at 20 °C to 3.2 days at 30 °C. Immature mortality was approximately 20% and did not differ between temperatures. Most mortality occurred during the first instar. Reproduction periods did not differ among temperatures, but at 25 and 30 °C more nymphs were produced (65.9 and 69.8 nymphs/♀, respectively) than at 20 °C (59,9 nymphs/♀) because of a higher daily reproduction. Intrinsic rate of increase was greatest at 25 °C (rm = 0.556 day−1). At 20 and 30 °C the intrinsic rate of increase was 0.426 and 0.510, respectively. On cv. ‘Aramon’, the development time of A. gossypii was approximately 20% longer at all temperatures. Immature mortality did not differ between the two cultivars. The intrinsic rate of increase on cv. ‘Aramon’ was 15% smaller than on cv. ‘Sporu’. The use of cucumber cultivars partially resistant to aphids is discussed in relation to biological control of cotton aphid in glasshouses. Development time and immature mortality on leaves of the middle and upper leaf layer of glasshouse grown cucumber plants (cv. ‘Aramon’) were comparable to development in the controlled climate cabinets. On the lower leaves immature mortality was much higher (approximately 82%) than on leaves of the middle (24.0%) and upper leaf layer (24.5%). Reproduction was less on the lower leaf layer (45.9, 70.5 and 70.1 nymphs/♀ on leaves of the lower, middle and upper leaf layer, respectively). Aphids, successfully parasitized by Aphidius colemani Viereck (Hymenoptera: Braconidae) only reproduced when they were parasitized after the third instar. Fecundity was 0.1 to 0.9 and 10.5 to 13.3 nymphs/♀ for aphids parasitized in the fourth instar or as adults, respectively. Reproduction of aphids that were stung but survived the attack was lower than for aphids not stung. Average longevity of these aphids was equal to the longevity of aphids not stung by A. colemani.

Four aphidiine parasitoid species (Hymenoptera: Braconidae) were evaluated with respect to their potential to control Aphis gossypii Glover (Homoptera: Aphididae) in glasshouse cucumbers. In a laboratory experiment thirty cotton aphids were offered to individual females for two hours. Aphidius matricariae Haliday parasitized less than six percent of the aphids and was ruled out as potential biological control agent. Ephedrus cerasicola Starý and Lysiphlebus testaceipes Cresson parasitized 23 and 26 percent of the aphids, respectively. Aphidius colemani Viereck parasitized 72 to 80 percent of the aphids. With the latter three species, experiments were performed in small glasshouses with cucumbers (Cucumis sativus L. cv. ‘Aramon’). As in the laboratory test A. colemani performed best; significantly more colonies were found and parasitization rates in the colonies were higher by A. colemani than by E. cerasicola and L. testaceipes. Because of the good correspondence between laboratory and glasshouse experiments, it is suggested that bad performance of an aphid parasitoid species in a simple laboratory trial might be sufficient evidence to disregard this species for further tests.

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Increasing problems with chemical control of cotton aphid, Aphis gossypii Glov., in vegetable crops necessitate development of a biological control programme. An endoparasitoid of cotton aphid, Aphidius colemani Vier., is one of the candidate control agents. Data on longevity, reproduction, and development of A. colemani with A. gossypii as host are presented in this paper. The parasitoid has a fecundity of 302 eggs per female at 20°C and 388 eggs per female at 25°C, a developmental period of 12.7 days at 20°C and 10.0 days at 25°C, and an immature mortality of 14.1 % at 20°C and 27.8 % at 25°C. The intrinsic rate of increase of the parasitoid is both at 20 and at 25°C comparable to the intrinsic rate of increase of the cotton aphid. Aphidius colemani seems, therefore, a promising candidate for biological control of cotton aphid. Zusammenfassung Untersuchungen zur Wachstumsrate von Aphidius colemani Vier. (Hym., Braconidae), einem Parasitoid von Aphis gossypii Glov. (Hom., Aphididae), in Abhängigkeit von der Temperatur Zunehmende Probleme bei der chemischen Bekämpfung der Baumwoll‐Laus, Aphis gossypii, in Gemüsekulturen machen die Entwicklung von biologischen Bekämpfungsverfahren notwendig. Der Endoparasitoid Aphidius colemani ist ein möglicher Kandidat für ein biologisches Bekämpfungsverfahren. In der vorliegenden Untersuchung werden Ergebnisse zu Lebensdauer, Reproduktion und Entwicklung von A. colemani mit A. gossypii als Wirt dargestellt. Der Parasitoid hatte bei 20°C eine Fekundität von 302 Eiern bzw. 388 Eiern/♀ bei 25°C; die Entwicklungszeit betrug 12,7 Tage bzw. 10,0 Tage und die Larvenmortalität 14,1 % bzw. 27,8 % bei 25 °C. Die Wachstumsrate des Parasitoiden entsprach bei beiden Temperaturen der der Baumwoll‐Laus. Aus diesem Grunde scheint A. colemani ein geeigneter Kandidat für die biologische Bekämpfung von A. gossypii zu sein.

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