Life history parameters for Nesidiocoris tenuis (Reuter) (Het., Miridae) under different temperature regimes

The development time for eggs and nymphs and female fertility were determined for Nesidiocoris tenuis Reuter (Het., Miridae: Dicyphini) at 15, 20, 25, 30, 35 and 40 +/- 1 degrees C, using tomato, Solanum esculentum (Miller), as substrate and eggs of Ephestia kuehniella Zeller as substitute prey. At 40 degrees C, N. tenuis was unable to develop and barely reproduced. Egg development ranged from 30.8 days at 15 degrees C to 6.3 days at 35 degrees C. The cumulative thermal requirements for the eggs were 148.6 degree days (degrees d) and the lower thermal threshold, 10.3 degrees C. The duration of the nymphal instar decreased from 55.9 days at 15 degrees C to 8.6 days at 35 degrees C. The thermal constant for the nymphs was 182.3 degrees d and the lower thermal threshold 11.7 degrees C. No nymphs survived at 40 degrees C, and the highest mortalities were at extreme temperatures (15 and 35 degrees C). Female and male weights were influenced significantly by temperature. The fertility of N. tenuis females was reduced greatly at 15 and 40 degrees C. The highest fertility during an observation period of 18 days following female emergence (79.5-60.0 nymphs per female) was within the temperature range of 20 to 35 degrees C. Fertility was related directly to female weight and temperature (r(2) = 0.932). Based on development, reproduction data and thermal requirements, the optimum temperature range for N. tenuis was established as being between 20 and 30 degrees C. Overall, N. tenuis is the most thermophilous of all dicyphines from vegetable crops in the Mediterranean area studied so far.