A new pest in vineyard under grass management model: study on the biological characteristics and control of Smaragdina nigrifrons

Abstract: 【Objective】For many years, our team have been working on organic cultivation management and pest control of wine grapes. Ground cover management model has been a new green management model currently implemented in the northern orchards. However, under the grass-covering system,new or secondary pests and diseases may increase in the orchards if the pasture type and planting and management models are not carefully chosen. These pests and diseases might become a new problem in fruit production. For example, a serious insect pest of wine grapes, Smaragdina nigrifrons(Hope)(Coleoptera: Eumolpidae) was found in the vineyard in Changli, China for the first time. This pest is highly harmful and occurs continuously in grass-covered orchards. In order to understand the occurrence and damage of the pest, the authors conducted field and lab investigations for three consecutive years. Its morphological characteristics were described, and its living habits, damage, and occurring pattern were observed, and the control methods were suggested.【Methods】Systematic field investigation was combined with indoor feeding and observation. Morphological characteristics of the beetles were observed under Primo Star microscope, and their taxonomic status was determined. The population dynamics and occurrence pattern were monitored by yellow cards trapping technique. 【Results】 The results showed that the adult of S. nigrifrons was long ovate. Female adults were 4.5 to 5.9 mm in length and 2.2 to 3.0 mm in width; males were 4.0 to 5.6 mm in length and 1.9 to 2.6 mm in width. Their head was black, the top was highly convex, and the leading edge had a wavy fold. There was no obvious boundary between the lip base and the forehead, which was slightly raised with numerous deep points.The tentacles were short and thin. The basal 4 knots of the tentacle were yellowish brown, the other sections were brown or black, and the sections after the 5 th section were jagged. The chest was red brown or yellow brown. The scutellum and the elytra were yellow brown or red brown, and the elytra had wide black transverse band. Male's abdomen penultimate web was raised and female's was sag. The adults of S. nigrifrons do damage on the tender new leaves. They had pseudo-lethality, coming out during the day and hiding at night. Generally it damaged tender leaves on the top of the canopy, with irregular notches in the injured leaves. The damage rate of local wine grape reached 100%. The adults usually appeared in July and August and might have one generation a year. They were active during 8:00 to 11:00 and 15:00 to 18:00. They had no phototaxis but had feigned death. In addition to harming the top leaves of wine grape trees, they also harmed the inter-row weeds, and the damage in the grass growing area was significantly more serious than in the weeding area.【Conclusion】It is speculated that the occurrence and harm of S. nigrifrons in the wine grape vine of Changli Langes Winery is closely related to the implementation of the new orchard management mode with grass cover, indicating that it has potential risk. Therefore, it is extremely important to carry out a risk assessment analysis of S. nigrifrons. The occurrence and damage of S. nigrifrons in other fruit orchards in the north, especially in slopes, semimountainous areas and mountainous areas, needs further investigation.