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Beneficial rhizobacterium provides positive plant–soil feedback effects to Ageratina adenophora

SUN Yuan-yuan, ZHANG Qiu-xin, ZHAO Yun-peng, DIAO Yue-hui, GUI Fu-rong, YANG Guo-qing

2021, 20 (5): 1327-1335. DOI: 10.1016/S2095-3119(20)63234-8

Abstract （123） PDF in ScienceDirect

Rhizosphere microbial communities play important roles in facilitating or inhibiting the establishment of exotic species. Since some invasive plants interact with soil microbial communities such as rhizosphere bacteria, changes triggered by rhizosphere bacteria may alter competitive interactions between exotic and native plants. This study compared the Bacillus cereus content in soils with different degrees of Ageratina adenophora invasion, and investigated the effects of A. adenophora allelochemicals on B. cereus growth and soil characteristics and the feedback effects of B. cereus on A. adenophora growth. Bacillus cereus content in the rhizosphere of A. adenophora increased with intensification of the invasion process, and newly invaded soil contained almost twice as much bacteria as noninvaded soil. When rhizosphere soil was added to the root exudates of A. adenophora, the contents of B. cereus were twice as much as the control, except on the first day. Certain soil parameters increased significantly, such as ammonium nitrogen (NH₄⁺-N) and available phosphorus (AP), which were increased by 41 and 27%, respectively. Soil treatment with B. cereus promoted the degradation of two allelochemicals from the rhizosphere of A. adenophora, amorpha-4,7(11)-dien-8-one and 6-hydroxy-5-isopropy1-3,8-dimethyl-4a,5,6,7,8,8a-hexahydraphthalen-2(1H)-one, to varying degrees; and increased the germination rate by 50%, root length by 117%, shoot length by 48% and fresh weight by 81% for A. adenophora compared to those of untreated soil. Our results confirmed that the invasion of A. adenophora will promote an increase of B. cereus, a beneficial rhizosphere bacterium, which in turn induces a positive feedback effect on A. adenophora.

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Effects of a novel mesoionic insecticide, triflumezopyrim, on the feeding behavior of rice planthoppers, Nilaparvata lugens and Sogatella furcifera (Hemiptera: Delphacidae)

ZHU Jun, SUN Wen-qing, LI Yao, GE Lin-quan, YANG Guo-qing, XU Jian-xiang, LIU Fang

2020, 19 (10): 2488-2449. DOI: 10.1016/S2095-3119(20)63197-5

Abstract （149） PDF in ScienceDirect

The rice planthoppers, Nilaparvata lugens and Sogatella furcifera, are important sap-sucking pests of rice in Asia. The mesoionic insecticide triflumezopyrim was previously shown to be highly effective in controlling both N. lugens and S. furcifera. In this study, electropenetrography (EPG) was used to evaluate the effect of three triflumezopyrim concentrations (LC₁₀, LC₅₀ and LC₉₀) on the feeding behavior of N. lugens and S. furcifera. EPG signals of planthoppes indicated that there were six different waveforms NP, N1, N2, N3, N4, and N5, which corresponded to non-penetration, stylet penetration into epidermis, salivation, extracellular movement of stylet, sap ingestion in phloem, and water ingestion in xylem during feeding. Compared to untreated controls, triflumezopyrim at LC₅₀ and LC₉₀ prolonged the duration of the non-penetration period by 105.3 to 333.7%. The probing frequencies of N. lugens exposed to triflumezopyrim at LC₁₀ and LC₅₀ were significantly increased; however, the probing frequencies of S. furcifera showed a significant decrease when exposed to triflumezopyrim at all concentrations. Triflumezopyrim exposure prolonged the duration of salivation and shortened the duration of extracellular movement. The duration of phloem sap ingestion decreased from 37.2 to 77.7% in the LC₅₀ and LC₉₀ treatments, respectively. Differences in feeding behavior in response to triflumezopyrim and pymetrozine were minimal. In summary, the results show that the LC₅₀ and LC₉₀ concentrations of triflumezopyrim inhibit the feeding activities of N. lugens and S. furcifera mainly by prolonging the duration of non-penetration and by shortening the duration of phloem sap ingestion, which may foster more efficient use of triflumezopyrim in Asia.

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Selectivity and sublethal effects of some frequently-used biopesticides on the predator Cyrtorhinus lividipennis Reuter (Hemiptera: Miridae)

DAI Wei, LI Yao, ZHU Jun, GE Lin-quan, YANG Guo-qing, LIU Fang

2019, 18 (1): 124-133. DOI: 10.1016/S2095-3119(17)61845-8

Abstract （319） PDF （783KB）（226）

The green miridbug, Cyrtorhinus lividipennis, is an important predator of the rice brown planthopper, Nilaparvata lugens. In this study, the selective toxicity of seven commercial biopesticides for C. lividipennis was examined under laboratory conditions; abamectin was the most selective to C. lividipennis, followed by matrine and azadirachtin. Veratridine, rotenone, Bacillus thuringiensis and Beauveria bassiana showed less selectivity for C. lividipennis. Subsequently, matrine, abamectin and azadirachtin were selected for sublethal assessments with respect to C. lividipennis due to their high toxicities to N. lugens. C. lividipennis treated with sublethal concentrations (LC₁₀ and LC₂₀) of the three biopesticides could distinguish volatiles released from healthy and N. lugens-infested plants indicating that the biopesticides tested did not affect the foraging ability of surviving miridbugs. Azadirachtin decreased the consumption capability of C. lividipennis when the densities of N. lugens were 20, 30, 40 and 50 insects per vial. Sublethal concentration treatment did not impact the pre-oviposition period or egg hatchability of C. lividipennis. However, the fecundity of C. lividipennis exposed to azadirachtin and abamectin increased by 27–41% compared to the untreated individuals. In summary, abamectin or matrine together with C. lividipennis could be considered an effective, sustainable pest management strategy for rice.

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Rice Grain Damage by Combination and Sequence Infestations by the Rice Leaffolder, Cnaphalocrocis medinalis Guenee (Lepidoptera: Pyralidae), and the White-Backed Rice Planthopper, Sogatella furcifera Horváth (Hemiptera: Delphacidae)

JIANG Li-ben, ZHU Zhan-fei, GE Lin-quan, YANG Guo-qing, WU Jin-cai

2014, 13 (11): 2460-2470. DOI: 10.1016/S2095-3119(14)60745-0

Abstract （1241） PDF in ScienceDirect

The rice leaffolder (RLF), Cnaphalocrocis medinalis Guenée (Lepidoptera: Pyralidae), and the white-backed rice planthopper (WBPH), Sogatella furcifera Horváth (Hemiptera: Delphacidae), are major insect pests in China and several other Asian countries. These two pests commonly occur simultaneously or in a temporal sequence. Thus, the investigation of the effect of complex infestations or temporal sequence infestations by these pests on rice yield has a practical significance for the control of these pests. The present study comprised experiments with the following four different variables in potted rice at the tillering stage: single pest species infestation, complex infestation, complete combination infestation and temporal sequence infestation (C. medinalis infestation prior to S. furcifera and S. furcifera infestation prior to C. medinalis). The results showed that the four infestations resulted in a significant decrease in 1 000-grain weight (1 000GW) and rate of yield loss (RYL) but an increase in blighted grain rate (BGR), with a significant positive correlation with the infestation density. However, the influences of the complex infestation, complete combination infestation or sequence infestation on the 1 000GW, BGR and RYL were greater than those of the single pest species infestations but did not have addition effects, i.e., the effects of the complex infestation and combination infestation or sequence infestation on the 1 000GW, BGR and RYL were less than the additive effects of the two single pest species infestations at the same densities. In the condition of the same total infestation pressure, no significant differences in the 1 000GW, BGR and RYL were found between C. medinalis infestation prior to S. furcifera and S. furcifera infestation prior to C. medinalis as well as between the sequence infestation and the complex infestation.

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Effects of Pesticide Applications on the Biochemical Properties of Transgenic cry 2A Rice and the Life History Parameters of Nilaparvata lugens Stål (Homptera: Delphacidae)

SHI Zhao-peng, DU Shang-gen, YANG Guo-qing, LU Zhen-zhen , WU Jin-cai

2013, 12 (9): 1606-1613. DOI: 10.1016/S2095-3119(13)60596-1

Abstract （1211） PDF in ScienceDirect

Effects of transgenic Bt rice on non-target pests following pesticide applications plays an important role in evaluating the ecological safety of transgenic rice. Changes of the life history parameters of laboratory population of Nilaparvata lugens feeding on transgenic Bt rice T2A-1 and its parental line cv. MH63 as the control, and the contents of oxalic acid and soluble sugar following three pesticides (triazophos, jinggangmycin and chlorantraniliprole) treatments were investigated in this paper. Results showed that the population parameters of N. lugens and the physiological and biochemical parameters of rice did not differ significantly between T2A-1 and MH63 without pesticide application. But, the emergence rate (ER), the nymphal number of next generation (NN), and the index of population trend (IP) on T2A-1 treated with 10 mg L-1 of triazophos were significantly higher than those on MH63, respectively, while the hatchability (HB) on T2A-1 treated with the three pesticides were obviously lower than those on MH 63. Furthermore, the content of oxalic acid in MH63 treated with 20 mg L-1 triazophos and, 40 and 80 mg L-1 chlorantraniliprole was significantly higher than that in T2A-1, while the content of soluble sugar in T2A-1 treated with 400 mg L-1 jinggangmycin was significantly higher than that in MH63. The results above indicated that triazophos in a low dose could cause a more favor of T2A-1 to population growth of N. lugens compared with MH 63.

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