【Objective】Potato tuberworm (Phthorimaea operculella) is an important pest on potatoes, which seriously affects the quality and value of potatoes. The objective of this study is to clarify the adaptability of P. operculella on different potato tuber varieties, and to provide a basis for screening resistant potato varieties and developing effective integrated pest management strategy.【Method】To evaluate the adaptability of P. operculella on different tuber varieties and screen the high natural-resistance tubers, in this study, four varieties (Xiabodi, Longshu No. 4, Longshu No. 12 and Kexin No. 17) which were planted in a large scale at present were selected as tested materials to determine the development and population parameters of P. operculella on different tuber varieties using an age-stage specific two-sex life table.【Result】There were significant differences in larval stage, pupal stage and female longevity of P. operculella feeding on different tuber varieties. Compared with those fed on Xiabodi, Longshu No. 4 and Longshu No. 12, those fed on Kexin No. 17 exhibited significantly longer larval stage (15.18 d) and pupal stage (8.10 d), and the female longevity (8.46 d) was shorter than the other three varieties. Moreover, the longevity of male was significantly higher than female in a same variety. The fecundity of P. operculella feeding on Xiabodi (235.06 eggs) and Longshu No. 4 (254.48 eggs) was significantly larger than that fed on Kexin No. 17 (165.71 eggs). In addition, there were significant differences among intrinsic rate of increase (r), finite rate of increase (λ), net reproductive rate (R0) and mean generation time (T) of P. operculella feeding on different tuber varieties. The r, λ, R0 values of P. operculella fed on Kexin No. 17 (r=0.108, λ=1.125, R0=26.513) were significantly lower than those on the other three tuber varieties, and T value of P. operculella fed on Kexin No.17 (30.28) was significantly higher than those on the other three tuber varieties. Larvae feeding preference experiments showed that the larvae fed on Xiabodi and Longshu No. 4 in preference to Kexin No. 17. With the increase of age, the selectivity gradually decreased. 【Conclusion】There was a different adaptability of P. operculella among different potato tuber varieties. Xiabodi and Longshu No. 4 are the most suitable hosts, followed by Longshu No. 12, and Kexin No. 17 is the least suitable host. In areas where P. operculella is seriously damaged on potato field system, planting potato varieties with low adaptability can be selected as an important strategy for reducing population of P. operculella in the field.
【Objective】The objective of this study is find out the difference of electrophysiological responses of potato tuberworm (Phthorimaea operculella) with different sexes and mating states to potato volatiles, and to provide a reference for the chemical ecological control of P. operculella.【Method】Electroantennogram (EAG) responses of virgin female, mated female and unmated male P. operculella to 16 volatile compounds (including 6 aliphatic compounds viz. 1-octen-3-ol,1-butanol, heptanal, octanal, nonanal and decanal, 4 aromatic compounds viz. phenethyl alcohol, phenylacetaldehyde, acetophenone and methyl salicylate, and 6 terpenoids viz. α-pinene, p-cymene, (E)-β-ocimene, 1,8-cineole, (E)-β-farnesene and methyl jasmonate) released from potato tubers and plants were recorded, and the dose-responses to 6 compounds (including 1-octen-3-ol, heptanal, nonanal, acetophenone, methyl salicylate and (E)-β-ocimene) were also conducted.【Result】All the tested compounds could elicit EAG responses of P. operculella. Among them, the aliphatic alcohols elicited significantly greater EAG values in the virgin females and the unmated males, and aliphatic aldehydes elicited significantly greater EAG values in the mated females. However, the terpenoids elicited lower EAG values in all the tested P. operculella. At the dose of 1 000 μg, the same compound elicited varied antennal responses from the P. operculella with different sexes and mating states. Octanal, methyl salicylate and (E)-β-ocimene elicited stronger responses in virgin females than those in the mated females and the unmated males, while heptanal, nonanal and α-pinene elicited stronger responses in the mated females than those in the others. The compounds 1-octene-3-ol, phenethyl alcohol and phenylacetaldehyde elicited stronger responses in the males than those in the females. At the tested dose series (1, 10, 100 and 1 000 μg), EAG responses of P. operculella at 3 physiological states to 6 individual compounds increased with the increase of stimulation dose, and were far from saturation thresholds. For the same compound at different doses, EAG responses of the mated females varied significantly.【Conclusion】The virgin females and the unmated males of P. operculella are more sensitive to aliphatic alcohols, and the mated females are more sensitive to aliphatic aldehydes. However, both the females and males are less sensitive to terpenoid compounds. Among the responses to the individual compound, the mated females are more sensitive to heptanal, nonanal and α-pinene than the virgin females and the unmated males, so are their responses to the same compound at different doses.
Potato is one of the four staple crops in China together with wheat, rice and maize. It plays a key role in ensuring the national food security strategy, reasonably adjusting the agricultural planting structure, and implementing the poverty alleviation strategy. With the continuous expansion of potato planting area, the occurrence of diseases and insect pests in production and storage is becoming more and more serious. Potato tuberworm (Phthorimaea operculella) is a major potato pest, which originated in America and quickly spread to all over the world. Prevention and control strategy of P. operculella mainly include agricultural, chemical and biological methods. With the increasing consciousness of environmental protection, the use of sustainable and ecological green prevention methods of P. operculella sex pheromone has attracted considerable attention of agricultural scientists, biologists and chemists, which provides the possibility to reduce the excessive use and dependence of chemical pesticides. The sex pheromones of P. operculella mainly contain two chemical structures: 4E, 7Z-tridecadiene-1-ol acetate (PTM1) and 4E, 7Z, 10Z-tridecatriene-1-ol acetate (PTM2). The discovery and structure determination process of these two sex pheromones is very tortuous. The chemical synthesis method of these two sex pheromones started in the 1970s, developed in the 1980s and 1990s, and only a few strategies were reported in the 21st century. This process witnessed the rapid development of modern organic synthetic chemistry. How to construct E and Z olefin accurately and efficiently is a challenge for synthesis of PTM1 and PTM2. The key steps of PTM1 synthetic strategy mainly include alkyne reduction or rearrangement reaction, conjugation ring opening, organosilicon induced Beckmann reaction, cross coupling reaction and so on. Up to now, only two cases were reported about the synthesis of PTM2. Due to the addition of a Z-type olefin bond in the structure, the two synthesis routes of PTM2 adopt coupling reaction to introduce diyne block, and then 7Z, 10Z-olefin was synthesis by catalytic hydrogenation reduction of diynes by Raney-Ni or Lindlar-Pd. However, most of the synthetic routes are lengthy, low selectivity of E/Z configuration, and complicated procedure. Developing a facile and efficient synthetic method of sex pheromone of P. operculella will provide the necessary material source for the wide application of green integrated prevention and control technology of P. operculella in the field. It will play a positive role in insect sex pheromone trapping technology as an important means of pest prevention and control.
【Objective】The objective of this study is to determine the effect of combination of chemical and physical factors on oviposition behavior of potatoworm (Phthorimaea operculella), and to provide a basis for the development of behavior regulation technology of P. operculella.【Method】Tubers were treated with different methods: (1) soaked in heptanal, cineole solution and then dried, (2) wrapped with cotton gauze, or with cotton gauze loading tuber juice, respectively, then oviposition behavior parameters (including landing times, arresting time, ovipositor-probing times, amount of eggs) of mated females on the tubers were observed at the dark-phase (red light intensity: 1.0-1.5 lx) under the environment-controlled conditions of temperature (27±2)℃, relative humidity 50%-70%, and photoperiod 14L:10D.【Result】Females would arrest for longer time (arresting time), and more eggs would be deposited on the surface of the tubers when heptanal solution (0.5 mg·L-1) was applied onto the surface of tubers, but the times of ovipositor-probing and landing did not increase significantly. Significant reduction in arresting time, landing times and ovipositor-probing times, and more egg-deposition, were observed when heptanal solution at the concentration of 30 mg·L-1 was applied to the tuber surface. More eggs were laid on the surfaces of tubers, and no significant change in oviposition behavior (arresting time, landing times and ovipositor-probing times) occurred when cineole solution (6 mg·L-1) was applied. Application of cineole solution at the higher concentration (30 mg·L-1) would result in significant reduction in arresting time, landing times and ovipositor-probing times, and in more egg deposition outside the tuber. When tubers were wrapped with cotton gauze, more eggs were deposited on the tubers, the times of landing and ovipositor-probing decreased significantly, but no significant difference in arresting time appeared. Similar oviposition behaviors were observed when tubers were wrapped with cotton gauze loading tuber juice. Compared with the blank control, the treatment (tubers + cotton gauze loading heptanal (0.5 mg·L-1)) led to more eggs deposition and longer arresting time, and to significant reduction in times of ovipositor-probing and landing. Compared with the single use of heptanal (0.5 mg·L-1), it could significantly reduce ovipositor-probing times and landing times, and at the same time, it could significantly increase the amount of eggs on the tuber and the total amount of eggs. Compared with the single use of cotton gauze, there was no significant difference in each index.【Conclusion】Heptanal can stimulate mated female P. operculella to oviposit in more intensive time. At the concentration of 30 mg·L-1, heptanal will repel the females from the treated potato tuber; at the concentration of 0.5 mg·L-1, heptanal will show an attractive effect on mated female moths. Cineole (30 mg·L-1) only has repellent effect on moths, while wrapped with cotton gauze, cotton gauze soaked in tuber juice, cineole solution (6 mg·L-1) only show stimulating effect on oviposition of females. These results indicate a co-attractive of combination of the chemical stimulus (0.5 mg·L-1 heptanal) and the physical stimulus (cotton gauze).
