As consequence of the concern about the biosafety of genetically modified plants, biological and ecological studies are considered crucial for environmental risk assessment. Laboratory experiments were carried out in order to evaluate the transfer of the Cry1Ac Bt-toxin from a transgenic Bt-oilseed rape to a non-target pest, Myzus persicae Sulzer. Cry1Ac protein levels in plants and aphids were determined using a double sandwich enzyme-linked immunosorbent assay. Phloem sap from (Bt+) and (Bt-) oilseed rape plants was collected from leaves using a standard method of extraction in an EDTA buffer. Bt-toxin was present in phloem sap, with a mean concentration of 2.7 +/- 1.46 ppb, corresponding to a 24-fold lower level than in oilseed rape leaves. Toxin was also detected in aphid samples, with a mean concentration in the positive samples of 2.0 +/- 0.8 ppb. The evidence that Bt-toxin remains in herbivores, in this case an aphid, could be useful to clarify functional aspects linked to possible consequences of Bt-crops on food chains involving herbivore-natural enemy trophic systems. Further studies are needed in order to improve the knowledge on the functional aspects linked to the transfer of the Cry1Ac Bt-toxin from GM-oilseed rape to aphids and their possible consequence.

Field trials were carried out in Northern Italy in order to develop an agroecological approach to the control of Lygus rugulipennis Poppius (Rhynchota Miridae) on lettuce by using trap crops. Two treatments were compared: lettuce with trap crops, consisting of plots adjacent to alfalfa strips and lettuce without trap crops consisting of another four plots surrounded by bare soil. In 2000 alfalfa strips were not treated; on the contrary, in 2001 and 2002 localised chemical treatments were made weekly on the alfalfa strips. In 2002 the ratio between trap crops and lettuce areas was increased from 0.075 to 0.15. In addition, cultivar ‘Trocadero’, a cultivar less sensitive to Lygus damage, was compared to cultivar ‘Romana’. The results demonstrated a general efficiency of alfalfa as a trap plant for managing L. rugulipennis. The efficiency in preventing damage to lettuce was not sufficient in 2000 without localised chemical applications on alfalfa. The localised treatment of insecticides on alfalfa strips had a significant effect on reducing the extent of damage on lettuce plots adjacent to the trap crops. In 2002 the cultivar ‘Trocadero’ had a lower damage index than cultivar ‘Romana’. Alfalfa as a trap crop could be used for lettuce in periods of the year where the pest is not as abundant as it is in August and September. Managing Lygus bugs with trap crops is not advisable when the variety of lettuce is very sensitive to bug damage, thus trap crops can be effective for lettuce cultivar like ‘Trocadero’ but not for cultivar ‘Romana’.

As part of an environmental risk assessment study of exotic natural enemies used in inundative biological control, life-history characteristics of Harmonia axyridis (Pallas), Hippodamia variegata (Goeze) and Adalia bipunctata (L.) (Col., Coccinellidae) were quantified under laboratory conditions at 25degreesC on Myzus persicae (Sulzer) as prey. Comparative studies showed significant differences among pre-adult development times: H. axyridis developed slower ((X) over tilde = 19.8 days) than H. variegata ((X) over tilde = 18.1 days) and A. bipunctata ((X) over tilde = 18.4 days). Differences were also evident in the duration of egg, larval and pupal stages. No measurable differences among the three species were found for fecundity, oviposition rate and adult longevity. Harmonia axyridis exhibited the longest pre-oviposition ((X) over tilde = 7.4 days) and interoviposition ((X) over tilde = 3.6 days) periods and the shortest oviposition period ((X) over tilde = 13.7 days). The Bieri model was used to describe age-specific fecundity for the three species of coccinellids. The intrinsic rate of increase (r(m)), net reproductive rate (R-0) and mean generation time (T) were higher for H. variegata (r(m) = 0.114, R-0 = 52.75, T = 41.88 days) than for H. axyridis (r(m) = 0.089, R-0 = 26.27, T = 38.81 days) or A. bipunctata (r(m) = 0.081, R-0 = 18.49, T = 40.06 days). Our findings show that the biological traits of H. axyridis do not seem to be factors that may contribute to the invasiveness of this coccinellid.