Temperature responses and the occurrence of sexual forms of spotted alfalfa aphid (Hemiptera : Aphididae) in New Zealand

Abstract

The spotted alfalfa aphid (Therioaphis trifolii (Monell) forma maculata) produced sexual oviparous females at a day/night 10/14 h photophase in laboratory experiments. Only a small percentage of adults had this ability, and their fecundity was low. In the field a few sexual forms which produced only non-viable eggs were found in autumn. The minimum threshold temperatures for development were determined as 10.5 and 9.8°C in 1983 and 1984 respectively (higher than reported elsewhere). Hence, in New Zealand, spotted alfalfa aphid development rates are expected to be severely limited by the temperate climate.

Keywords:

• Hemiptera
• Aphididae
• Therioaphis trifolii f. macuiata
• spotted alfalfa aphid
• sexual formation
• temperature responses