Insect pests complex of common sage (Salvia officinalis L.) and their interactions with natural enemies

Common sage (Salvia officinalis L.) have been economically cultivated in many countries, but the production is still facing a number of challenges including significant production losses due to insect pests. This research studied: 1) insect pests of S. officinalis and their natural enemies, 2) incidence and economic impact of a key insect pest, Eucarazzia elegans (Ferrari) (Hemiptera: Aphididae) on S. officinalis and evaluations of the environmental factors influenced the aphid population, 3) the attractiveness of methyl salicylate (MeSA) lures, a synthetic herbivore-induced plant volatiles (HIPVs), to the natural enemies in the sage fields and its impact on the mint aphid, E. elegans growth population, and 4) the interaction of two generalist predators, Coccinella septempunctata Linnaeus and Adalia bipunctata (Linnaeus) (Coleoptera: Coccinellidae) to control the mint aphid, E. elegans. Throughout the study, 11 insect orders spread into 31 families and 51 species consist of 19 natural enemies, 3 pollinators and 29 insect pests. Micantulina stigmatipennis (Mulsant & Rey), Eupteryx gyaurdagicus Dlabola (Hemiptera: Cicadellidae), Aphis passeriniana (Del Guercio), Eucarazzia elegans (Ferrari) (Hemiptera: Aphididae), Dysmiscoccus angustifrons (Hall) (Hemiptera: Pseudococcidae), Chrysolina americana (Linnaeus) (Coleoptera: Chrysomelidae) and Thrips tabaci Lindeman (Thysanoptera: Thripidae) were determined as the key insect pests. A. passeriniana was a new species recorded in Turkey whilst E. elegans were known as the new species recorded in Izmir. M. stigmatipennis has been found to feed on S. officinalis and report as a host plant for the first time. A survey and laboratory experiments on incidence rates and economic impact of E. elegans on S. officinalis revealed that E. elegans infested old leaves with an incidence rate of 9.5% in the early spring and then migrated to young leaves and blossom at the beginning of the summer with the incidence rate of 1.1%. The seasonal distribution of the aphid was affected more by temperature than humidity and rainfall. Although the aphid infestation had no differences on the quantity of the essential oil, some of the essential oil components were markedly different from the control. The total plant weights (fresh and dry) with the normal and double infestation rate were decreased about a third and more than a half compared to the control, respectively. Aphids feeding on common sage beyond 8-10 weeks caused more than 50% yield loss. The highest cost-benefit ratio was achieved in plots where six insecticide applications were made. The experiment with MeSA lures as an artificial herbivore-induced plant volitiles (HIPVs) recorded several numbers of natural enemies of which Syrphidae (Diptera), Rhagonycha fulva (Scopoli) (Coleoptera: Cantharidae), and C. septempuctata (Coleoptera: Coccinellidae) were abundantly caught on traps adjacent to the MeSA odors. In semi-field experiments, E. elegans populations were significantly reduced on treated common sage plants when it exposed to the natural enemies. When experiments were set in laboratory condition, the number and population growth rates of aphid did not differ between treated and untreated implicating no effects of MeSA on aphid population rate and emphasizing the role of natural enemies for controlling the mint aphid, E. elegans population. The study with two generalist adult predators, C. septempunctata (Cs) and A. bipunctata (Ab) (Coleoptera: Coccinellidae) to control aphid E. elegans resulted that in the culture jar the conspecific species Cs + Cs and heterospecific species Cs + Ab combinations showed antagonistic effects, but the synergistic effect for conspecific Ab+Ab. In the petri dish, however, the conspecific Ab + Ab combination exerted an additive effect, but a synergistic effect for conspecific Cs + Cs and heterospecific Cs + Ab. These prey consumption patterns were influenced by the combination hetero-/conspesific (F = 410.86; P < 0.000; df = 4) and the interaction among the two independent factors (species × arena)(F = 58.87; P < 0.000; df = 4) but not by type of arena alone (F = 0.817; P = 0.369; df = 1). Here, the prey preference in these ladybirds has primarily associated with a diversity of ladybird rather than habitat structure complexity.