Occurrence dynamics of Ophraella communa and their control efficacy against Ambrosia artemisiifolia and security to non-target plants

【Objective】 To study the occurrence dynamics of Ophraella communa in Laibin， Guangxi， as well as their control efficacy against Ambrosia artemisiifolia and security to non-target plant， which could provide basis for drawing up biological control strategies of Ambrosia artemisiifolia. 【Method】 Laboratory experiments and field surveys were conducted to analyze Ophraella communa developmental characteristics at different temperatures， natural population dyna-mics， control efficacy against Ambrosia artemisiifolia， and feeding bias and oviposition preferences to local non-target plants in Laibin. 【Result】 At 15 ℃， the female of Ophraella communa could lay eggs normally with low mean fecundity， the egg production was low and the hatching rate was low， and the larvae could not grow and develop normally. At 20 ℃， 25 ℃， and 30 ℃， the average generation durations were 43.9， 36.2， and 29.4 d respectively， with the shortest durations being 31.3， 27.5， and 21.0 d. The mean fecundity per female was 191.8， 347.6， and 518.6 eggs， with hatch rates of 98.0%， 100%， and 100%， larval pupation rates of 61.3%， 94.7%， and 99.0%， and adult emergence rates of 88.5%， 96.4%， and 98.7% respectively. In Laibin， Ophraella communa could complete an average of 7-8 generations per year with great generational overlap， overwintering as adults on Ambrosia artemisiifolia， laying eggs from early March， and reaching population peaks from June to August. The highest plant height control efficacy and the highest visual control efficacy against Ambrosia artemisiifolia were 76.0% and 76.3% respectively. Field investigation results showed that Ophraella communa only slightly fed on the invasive plant Xanthium chinense， and no feeding or oviposition behavior was observed on crops such as sugarcane， corn， peanuts， sweet potatoes， or other native plants. Indoor test results indicated that the 3^th instar larvae of Ophraella communa could slightly feed on Dendranthema×morifolium ‘Pompon’， Bidens pilosa， Eupatorium adenophorum and Sphagneticola trilobata， but they could not grow and develop normally， and Ophraella communa could not feed or lay eggs on other non-target plants. 【Conclusion】 Ophraella communa has a long suitable temperature period for development and multiple generations in Laibin. It has a good control effect on Ambrosia artemisiifolia and has strong host specificity， with high safety for non-target plants. However， the natural population of Ophraella communa has large fluctuation and low stability. It is recommended to strengthen pest monitoring and stabilize the field population scale through artificial supplementary release， transfer and auxiliary conservation to improve the control effect on Ambrosia artemisiifolia.