Volume 21 (2012) Issue I
Entomologia Hellenica 21 (2012): 25-38.
Regional Research Station, Punjab Agricultural University, Ludhiana -141004, Punjab, India
Laboratory of Agricultural Entomology, Benaki Phytopathological Institute, 8 Stefanou Delta, 14561 Kifissia, Greece
Cotton mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) is an important cotton pest in Punjab, India. Development of the immature stages (four instars in female and five in male) of P. solenopsis was observed at nine constant temperatures (15, 18, 20, 25, 30, 34, 35, 38, 40°C). Using the linear model, the lower temperature threshold (tmin) for development was estimated to be 4.93 and 2.95°C and the thermal constant (K) was 333.33 and 454.54 degree days for female and male, respectively. In addition, three nonlinear models (Lactin, Bieri-1 and 3rd order polynomial) were tested to describe the relationship between temperature and development rate and to estimate the upper developmental threshold (tmax) and the optimum temperature for development (topt). Our results proved that the Bieri-1 and Lactin models and provided the best fit (r2 = 93,4 – 99,9%) and estimated accurately all the three critical temperatures, ranged tmin = 5.06 – 5.25°C, topt = 33.55 – 33.60°C, tmax = 39.99 – 40.00°C, for the total development of females and tmin = 2.82 – 3.16°C, topt = 34.01 – 34.04°C, tmax =40.00 – 40.10°C, for the total development of males
Entomologia Hellenica 21 (2012): 39-43.
Laboratory of Agricultural Zoology and Entomology, Agricultural University of Athens, 75 Iera Odos, GR - 118 55 Athens, Greece;
On June 2012, the ash whitefly Siphoninus phillyreae (Haliday) (Hemiptera: Aleyrodidae) was recorded for the first time on pomegranate in Greece. Its occurrence was observed in a pomegranate orchard at Kato Tithorea, in Fthiotida. Information on its morphology, biology and distribution is presented.
Entomologia Hellenica 21 (2012): 13-24.
Benaki Phytopathological Institute, Department of Entomology and Agricultural Zoology, 8 Stefanou Delta, 145 61, Kifissia, Greece; e-mail: d.kontodimas@bpi.gr
Among several mathematical models used to describe the development or the fecundity of insects the equations of Enkegaard, Analytis, Bieri 1 and Bieri 2 could describe both biological features. In the current study these equations used to describe the development and fecundity of two pseudococcid predators [Nephus includens(Kirsch) and Nephus bisignatus (Boheman) (Coleoptera: Coccinellidae)] preying on Planococcus citri (Risso) (Hemiptera: Pseudococcidae) at constant temperatures (15oC - 35oC). All models have goodness of fit to data especially for development [R2adj, RSS and AIC ranged0.9908-0.9996, 0.0019-89.1752 (x10-4), and (-75.43) – (-31.07) respectively]. Optimum temperature (Topt) and upper threshold (Tmax) were calculated accurately by all models (Topt ranged 32.6-34.0oC for N. includensand 30.0-30.6oC for N. bisignatus and Tmax ranged 35.0-38.8oC for N. includensand 33.1-36.0oC for N. bisignatus, respectively). Lower temperature threshold (Tmin) was calculated accurately by Bieri-1 model (11.0 and 10.0oC for N. includensand N. bisignatus respectively) whereas Analytis model underestimated it (8.0 and 4.9oC). As far as fecundity is concerned the respective values were better fitted near the optimum temperature (25oC) [R2adj, RSS and AIC ranged 0.8246-0.9704, 9.2729-24.0736 and (-246.82) – (-115.34) respectively]. Conclusively, from the tested models the Bieri-1 equation was proved as the most appropriate for the reason that could estimate correctly all the requested parameters concerning the development (Tmin, Topt, Tmax) as well as it could describe sufficiently the fecundity trend of the two predators.
Entomologia Hellenica 21 (2012): 3-12.
Laboratory of Agricultural Zoology and Entomology, Agricultural University of Athens, 75 Iera Odos str., 118 55, Athens, Greece
The host plant selection of the predator Macrolophus melanotoma (Costa) (=M. caliginosus Wagner) (Hemiptera: Miridae) was studied between: i) its major non-crop host plant, Dittrichia viscosa L. (W. Greuter) (Asteraceae)and the solanaceous plants eggplant, pepper and tomato, and ii) between eggplant, pepper and tomato, in choice experiments. The experiments were performed in cages where two potted plants without prey were placed. In each replicate, an adult predator was released in the centre of the cage or on the solanaceous plant. The position of the released predator in each cage was recorded at intervals of 20min, 1, 2, and 24h after its introduction. The results showed that M. melanotoma had a high selection preference rate for its origin host plant (D. viscosa) irrespectively of the solanaceous plant that was present in the cage. The experiments investigating the relative preference of M. melanotoma when given access only to solanaceous plants revealed that it preferred eggplant at higher rates than pepper and tomato. These data indicate that M. melanotoma originating from D. viscosa patches might have a very low potential to colonize pepper or tomato crops in the open field. However, its potential to colonize eggplant crops should be further evaluated.
