The efficacy of entomopathogenic agents against halyomorpha halys (hemiptera: Pentatomidae)

With the aim ofestablishing the efficacy of entomopathogenic agents experiments were carried outunder laboratory conditions against the third instar nymphae and imagoes. The following entomopathogenic nematodes (EPN) were used as agents in the experiments: Steinernema tbilisiensis, S. thesami, S. gurgistana, S. carpocapsae, Heterorhabditis bacteriophora and the local strain of the fungus Isaria fumosorosea (Wize). The experiments were carried out in two stages: at the first stage 100 nematodes were used against each insect, while at the second stage – 200 nematodes were applied. In parallel to this the efficacy of two concentrations of the fungus I. fumosorosea- 1.108 conidia/ml and 3.108 conidia/ml- was testedagainst the pest insect. On the second stage of experiment EPN and the fungus were jointly applied against the H. haly as a combination at high doses (200 nematodes + fungus I. fumosorosea - 3.108). The results of experiments have shown that while applying separately EPN and the fungus against nymphae and imagos, S. carpocapsae and the fungus H. bacteriophora turned out tobecomparatively effective: the effect of low dose of S. carpocapsae against nymphae was 77.2% and against imagoesit was equal to 62.2%. The effect of high dose was 82.4% and 65.3% respectively. As a result of application of low doses of H. bacteriophora 79.6% mortality of nymphae and 69.0% mortality of imagoes was achieved. When using high doses of this agent, the 83.3% of nymphae and 73.7% of imagoes were killed. EPN and the fungus were used in experiments in combination as well: the joint effect of S. carpocapsae and the fungus H. bacteriophora was 94.2% mortality of nymphae and 88.5% mortality of imagoes of H. halys. Combination of H. bacteriophora and I. fumosorosea yielded 95.6% and 90.5% mortality rate of nymphae and imagoes respectively. At all stages of the experiment emtomopathogenic agents revealed higher effect against nymphae as compared with imagoes. Our experiments have demonstrated that the combined applicationofEPN and fungus was more effective, that application of the same agents separately. The nematodes S. tbilisiensisandS. thesami, which turned out to be less effective at the first stage of experiment have revealed higher effect against the pest when applied in combination with the fungus.