Performance evaluation of spirodiclofen, spirotetramat and carboxymethyl cellulose-B for management of Cacopsylla pyri

The pear psyllid [Cacopsylla pyri (L.), (Hemiptera: Psyllidae)] represents one of the most economically significant pests of pear in Serbia and worldwide. It causes direct damage throughout feeding on young stems and leaves, but also creates favourable conditions for the development of plant diseases. In this article susceptibility of C. pyri to spirodiclofen, spirotetramat, and their combinations with foliar fertilizer (carboxymethyl cellulose-boron, CMC-B) was investigated in order to assess their efficacy. Experiments were conducted in accordance with standard OEPP/EPPO methods, in field trials on two localities in the Republic of Serbia (Kula, Vrbas), during 2020/21. Results of the field trials indicate good efficacy for all variants in pear psyllid control in pear orchards. The high efficacy of spirodiclofen (87.4–95.4%), spirotetramat (82.5–91.8%), spirodiclofen + CMC-B (90.3–99.8%), spirotetramat + CMC-B (89.5–96.8%) was achieved at both localities seven days after treatment during 2020/21 field trials. Also, it can be concluded for examinations 14 days after treatment, where the efficacy of spirodiclofen (84.9–92.0%), spirotetramat (81.2–91.7%), spirodiclofen + CMC-B (88.9–97.5%), and spirotetramat + CMC-B (82.3–92.5%) was high at both of investigated localities. Based on the obtained results it can be concluded that the high efficacy of the researched insecticides is a good indicator of C. pyri susceptibility in pear orchards.

Residue and dissipation dynamic of spinetoram insecticide in pear fruits

Cacopsylla pyri (Linnaeus, 1758) is the most significant and widespread pear pest. It attacks the pear only, causing direct and indirect damages. This study was conducted in order to evaluate the efficacy of insecticide spinetoram in the control of C. pyri. The experiment was set up according to EPPO methods, at the locality Kula (Republic of Serbia) in a pear orchard (Williams variety). Spinetoram (250 g/kg a.i., WG) was foliar applied in the amount of 0.3 kg/ha, during overlapping pest generations, when pear was on BBCH 75 scale. The efficacy was evaluated through the number of larvae aged L₁–L₃ and L₄–L₅. Spinetoram has shown satisfying efficacy, especially in the control of L₁–L₃ larvae (81.6%). In a dissipation study, spinetoram residues in pear fruits were determined using QuEChERS method followed by HPLC-DAD. The method was validated to fulfill SANTE/12682/2019 criteria. Three days after the application, spinetoram residues in pear fruits were below the MRL (0.2 mg/kg). The results have shown that spinetoram dissipation pattern followed the first-order kinetics (R²= 0.979) with a half-life of 2.17 days, in pear fruits. This study suggests that spinetoram could be safely used in pear, and it could take an important place in insecticide resistance management.

Esterase, Glutathione S-Transferase and NADPH-Cytochrome P450 Reductase Activity Evaluation in Cacopsylla pyri L. (Hemiptera: Psyllidae) Individual Adults

Cacopsylla pyri (L.) (Hemiptera: Psyllidae) is a key pest of pear orchards in Spain. The large number of insecticide treatments necessary for control may be an important contributor to the emergence of resistance. Laboratory toxicity and biochemical assays are necessary to validate the existence of insecticide resistance and establish the underlying mechanisms. All the methodologies developed to evaluate enzyme activity in C. pyri to date have incorporated “pools” of adults to detect minimum activity ranges. In this study, we determined the optimal working conditions for evaluation of the activities of esterase, glutathione S-transferase and NADPH-cytochrome P450 reductase in individual insects via colorimetric methods using a microplate reader. The main factors affecting enzymatic analysis activity, such as enzyme source and substrate concentration, filter wavelength, buffer pH, reaction time and additives, were evaluated for optimization. Determining the frequency of resistant individuals within a population could be used as an indicator for the evolution of insecticide resistance over time. Two laboratory strains, one of them selected with cypermethrin, and two field populations were analyzed for this purpose. The data obtained revealed high values and great variation in the activity ranges of esterase (EST) in the insecticide-selected population as well as in the field populations validating the applied methodology.

Potencijal entomopatogenih gljiva Metarhizium spp. u suzbijanju štetnih kukaca

Radi otpornosti kukaca prema pojedinim kemijskim pesticidima, i sa svrhom proizvodnje hrane bez ostataka pesticida biološka zaštita biljaka od štetnih kukaca sve više je od značaja. Biološke metode se zasnivaju na primjeni prirodnih sredstava kao što su patogeni, paraziti i grabežljivci štetnih kukaca. Cilj ovog rada je prikazati prednosti i nedostatke pri upotrebi mikoinsekticida na bazi Metarhizium spp., uzimajući u obzir biologiju ovih gljiva, njihovu interakaciju s biljkom, okolišem, drugim organizmima i agrokemikalijama, te dostupnost mikoinsekticida na tržištu. Opisani su uspješni primjeri primjene ovih entomopatogenih gljiva u suzbijanju žičnjaka (Elateridae) i maslinove muhe (Bactrocera oleae), običnog crvenog pauka (Tetranychus urticae) i kruškine buhe (Cacopsylla pyri). Učinkovitost Metarhizium spp. u suzbijanju nekih vrsta kukaca je usporediva s metodom primjene kemijskih insekticida. Osim kao biopesticid, smatraju se i biostimulatorima, odnosno biofertilizatorima jer su endofiti. Dostupnost, visoka cijena mikoinsekticida te mali broj istraživanja u polju razlozi su slabe primjene u praksi.