The last time span, of protected areas of forest ecosystems established raise of a variety of problems regarding frequency and intensity of the attack carried out by the rich pest complex affecting the trees' state of health. The current legislation forbids the application of pests control measures which can affect the biodiversity of these ecosystems. Species belonging to the useful entomofauna may interfere in the decrease of pest populations in these areas. The study of the parasitoid and predator complex has thus become a very topical research field, and these type of studies were carried out in Natural Park Apuseni, Romania. With the aim to identify present parasitoids and predators, 24 spruce logs provided from physiological weakened trees of 20-25 cm diameter and 1 m length were placed in 6 locations, in order to be populated by the spruce bark beetle Ips typographus (Linnaeus) as a trophic base of useful insect species. After its infestation the wood material was put in eclectors and analyzed weekly for the spruce bark beetle Ips typographus, its parasitoids and predators. After examining collected biological material, 6 parasitoid species were identified which determined a 4.8% parasitization in unmanaged and 2.3% parasitization in managed forests. The best represented Hymenopteran parasitoids were Roptrocerus xylophagorum (Ratzeburg) and Rhopalicus tutela (Walker). The found Coleopteran predators were from 12 species, which belong to 4 families. The most captures were of the species Nemosoma elongatum (Linnaeus), representing 50.3% of the total captured predators and Rhizophagus cribratus (Gyllenhaal), representing 9.5% of the captures.

In this study, different maize fields cultivated under different management systems were sampled to test corn leaf aphid, Rhopalosiphum maidis, populations in terms of total and endosymbiotic bacterial diversity. Corn leaf aphid natural populations were collected from traditionally managed maize fields grown under high agricultural and natural landscape diversity as well as conventionally treated high-input agricultural fields grown in monoculture and with fertilizers use, hence with low natural landscape diversity. Total bacterial community assessment by DNA sequencing was performed using the Illumina MiSeq platform. In total, 365 bacterial genera were identified and 6 endosymbiont taxa. A high abundance of the primary endosymbiont Buchnera and secondary symbionts Serratia and Wolbachia were detected in all maize crops. Their frequency was found to be correlated with the maize management system used, probably with fertilizer input. Three other facultative endosymbionts (“Candidatus Hamiltonella”, an uncultured Rickettsiales genus, and Spiroplasma) were also recorded at different frequencies under the two management regimes. Principal components analyses revealed that the relative contribution of the obligate and dominant symbiont Buchnera to the aphid endosymbiotic bacterial community was 72%, whereas for the managed system this was only 16.3%. When facultative symbionts alone were considered, the effect of management system revealed a DNA diversity of 23.3%.

Today, when somebody is talking about bark beetles management, there are two different approaches. The first one includes bark beetles in the category of pests and the second one includes bark beetles in the category of insects with important ecologic role in forest. From our point of view, up to particular limits, both approaches remain valid. Thus, in our research raise the problem of bark beetles population level into logging debris, which remains in the forest after clear-cutting. In our research, we started with the hypothesis that in logging debris a high number of bark beetles can multiply sufficient to install after that in neighbors standing trees. From our samples resulted seven bark beetles species as follows: Ips typographus, Ips amitinus, Ips acuminatus, Pityogenes chalcographus, Dryocoetes autographus, Hylurgops palliatus, Hylurgops glabratus. The most numerous were I. typographus (43%), P. chalcographus (40%), and H. palliatus (9%). The preferences for the thickness of logging debris had just P. chalcographus and H. palliatus. All the rest of the species preferred in equal mode thick or thin logging debris. Regarding the felling date of trees, we can affirm that cutting of trees early in spring may limit the beetles spreading. About logging debris management, our results show the necessity of their removal from forest and capitalization, because they are hosts for many bark beetles.

The functional role of the insect pathogen fungus Metarhizium anisopliae strain NCAIM 362 against the white grub cockchafer (Melolontha melolontha) larvae and southern European marshland pyralid (Duponchelia fovealis) larvae in a sweet potato cultivation was tested under greenhouse conditions. As a positive control, the effect of the same strain of M. anisopliae were compared with the effect of the synthetic insecticide alpha-cypermethrin. According to the results, alpha-cypermethrin was more effective against both the Coleoptera and Lepidoptera larvae, a lower number of surviving individuals as well as less damaged tubers were detected after the chemical treatment, compared with M. anisopliae.

In the present study, field surveys were conducted to detect potential associational susceptibility of crop plants (potato, alfalfa and maize) caused by Canadian goldenrod, Solidago canadensis (L.), one of the most common invasive weeds in Central and Eastern Europe, via plant associated virus vectoring aphids. Assessments were made in two major agricultural land types: crops grown under high input vs. low-input (LIF) conditions, with and without fertilizers and pesticides. The two most frequent aphid species, found both on Canadian goldenrod and crop plants, were the leaf-curling plum aphid, Brachycaudus helichrysi Kaltenbach and the glasshouse-potato aphid, Aulacorthum solani (Kaltenbach). Plant viruses in both weed and crop plants were identified using high-throughput sequencing of small RNAs. Peroxidase (POD) enzyme activity was tested in weed and crop plants to connect aphids feeding processes in weeds and crops. In addition, conceptual modeling was used to detect direct relationships between viruses and other crops. The Canadian goldenrod density was only relevant in the LIF regime. Furthermore, its association with B. helichrysi and associational susceptibility was detected only in LIF. In total, 18 viruses comprising 17 plant and one insect virus were detected in Canadian goldenrod, of which 11 were also detected in potato and alfalfa crops. POD activity was high and correlated with high aphid density in both weed and crop plants, suggesting a direct associational susceptibility between these plants through aphid infestation and viral transmission.