The fecundity of the pseudococcid predators Nephus includens (Boheman) and N. bisignatus (Kirsch) (Coleoptera: Coccinellidae), fed on Planococcus citri Risso (Hemiptera: Pseudococcidae), was studied at several constant temperatures (15, 20, 25, 30, 32.5 and 35°C). With additional data for the development of the immature stages, life-fecundity tables were constructed and some population parameters calculated. The average total fecundities of N. includens at the above temperatures were 49.2, 97.8, 162.8, 108.5, 87.4 and 31.1 eggs/female, and average longevities 99.5, 84.7, 69.5, 61.1, 49.6 and 30.1 days, respectively. The net reproductive rates (Ro) were 8.0, 32.2, 60.7, 32.6, 20.7 and 2.6 females/female, and the intrinsic rates of increase (rm) 0.014, 0.041, 0.083, 0.086, 0.077 and 0.024 females/female/day, respectively. The average total fecundities of N. bisignatus at 15, 20, 25, 30 and 32.5 ¿C were 54.7, 72.1, 96.9, 56.0 and 22.8 eggs/female, and average longevities 116.1, 108.7, 71.8, 68.8 and 43.7 days, respectively. The net reproductive rates (Ro) were 13.9, 26.4, 31.3, 15.2 and 3.6 females/female and the intrinsic rates of increase (rm) were 0.017, 0.035, 0.060, 0.051 and 0.024 females/female/day, respectively. The survival of females at each temperature was fitted using a Weibull distribution [S(t) = exp(-(t/b)c)]. Furthermore two mathematical models [Enkegaard equation: F = (a+b+x).e(c+d.x), Analytis equation: F = a.(x-xmin)n .(xmin- x)m] were fitted to the fecundity data.
The effects of temperatures of 15, 20, 25 and 30°C on the duration of premating and preoviposition periods of Harmonia axyridis reared on the aphid Aphis fabae, were compared in the laboratory. The course of oviposition was monitored at 25°C in females reared on Aphis fabae and the peak of egg laying was recorded at the age of 15 to 45 days. The size of egg groups (batch size), as well as daily and total fecundity was recorded. Half of the total number of eggs was laid in batches of 10-30 eggs. The mean daily and total fecundity reached a maximum of 42 and 1,641.6 eggs, respectively. Adult females oviposited for almost their entire life.
During the years 1994-1999, several hundreds of thousands of H. axyridis adults were released at various cultivations infested by aphids (citrus, vegetable and bean crops, maize etc.) and on ornamental plants in urban settings in central and southern Greece (mainly Attica and Peloponessos region) as well as on several islands. Between 1995-1999, spring sampling was conducted in some areas, just prior to releases, in order to determine if H. axyridis overwintered in the field. No presence of H. axyridis was recorded in any of the orchards where the predator had been released save in spring of 1998 and 1999 when small colonies (<50 individuals) of overwintered H. axyridis adults were observed in the Attica region. The above results suggest an inability of released H. axyridis populations to establish in Greece, although in some areas this species became an important biocontrol agent during the growing season.