| Contarinia maculipennis Felt belongs to Contarinia of Diptera, Cecidomyiidae. It is a new invasive pest of Hainan province in recent years and distribution in Sanya, Ledong, Dongfang, Wenchang at present. This pest has become an important pest of local Dendrobium flower production, and has a serious threat to the tropical orchid industry development in Hainan province. Currently, C.maculipennis Felt is a newly discovered invasive pest damaging Dendrobium buds in Hainan province, China. However, biological characteristics, occurrence damage and control strategies of C. maculipennis have not been reported in our country yet. In order to better understanding the characteristics of the pest, the research of biological characteristics has been done by observing the morphological characteristics, living habits and environmental factors (developmental threshold temperature and effective accumulated temperature). The occurrence of C.maculipennis in Hainan has been reported by field investigating and the optimal chemical control agents have been suggested by combining with larval indoor toxicity measurement and field efficacy test. The results were as follows:1.The morphological features of C.maculipennis was observed and described. The main identification characteristics between C.maculipennis and its related species are as follows:scales on membrane denser and darker in some areas and the membrane beneath is darker to form a pattern of light and dark areas;empodia as long as claws; Aedeagus extending beyond hypoproct; the first antenna flagellum of female is1.8～1.9times as long as the second antenna flagellum, uneven distribution of male antenna wire ring.The indoor pupation rate of instar larvae of C.maculipennis was about70%, the highest was76.5%.The indoor eclosion rate is about70%, there were two peaks of male and female in one day, respectively in the morning at6:00～10:00am and evening at16:00-19:00pm. In the temperature of18～30℃, the developing period of C.maculipennis shortened with the temperature gradually increased, negative correlation, and temperature has significant impact on the development period.The developmental threshold temperature of egg,larva,pupa and adult were2.96℃,6.82℃,6.27℃and6.27℃, the effective accumulated temperature were80.67,32.15,266.85, and28.51days/degrees. The development threshold temperature of the whole generation was6.07℃, the effective accumulated temperature was (406.57±47.46) day/degrees. Linear degree model and Logistic model fitting showed growth rate (V) and temperature (T) were positively correlated, it’s means that temperature (T) have significant effect on the rate(V) of development.According to meteorological data about annual average temperature and annual total accumulated temperature of Wenchang city, Dongfang city, Ledong county and Sanya city in Hainan Province,16,16.5,17and17generations per year could be occurred in these regions.2.The investigation was carried out in nine orchid planting bases of4cities of Hainan province,seven orchid planting bases has damage,the lightest damage rate was8.65%, the most serious damage rate was98.92%.The survey found that only dendrobium buds was harmed with larvae feeding in young tissues,other plants was not harmed,the mainly harm period in the field of C.maculipennis is from late June to middle of December.3.The toxicity index of6kinds of pesticides to the larvae of C.maculipennis indoor were Acetamiprid (LC5o:14.61mg/L)> Avermectins (LC50:20.09mg/L)> Spinetoram (LC50:26.28mg/L)> Beta Cypermethrin (LC50:28.17mg/L)> Imidacloprid (LC50:43.07mg/L)> Chlorpyrifos(LC5o:155.04mg/L). Field efficacy trials results showed that5%Acetamiprid EC exhibited best control in the field, the corrected efficacies were78.52%after spraying for3days.6%Spinetoram SC,3%Avermectins EW and10%Imidacloprid WP is better than others, the corrected efficacies were68.09%,60.99%and59.06%. After spraying for seven days,5%Acetamiprid EC also exhibited best control, the corrected efficacies were72.12%, the corrected efficacies of6%Spinetoram SC and3%Avermectins EW were60.83%and50.88%. Therefore, combined with the indoor toxicity and field test results, Acetamiprid is preferred for field control of C.maculipennis larvae, Chlorpyrifos and Spinetoram can be used alternately. |
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