Impacts of abiotic factors on population fluctuation of insect fauna of Vigna radiata and Tetranychus urticae Koch in Sindh, Pakistan

Effect of temperature and relative humidity on population dynamics of insect pests of mung bean was studied during mung bean growing season of 2005. Insect pests included thrips (Thrips tabaci Lind.) and field cricket (Gryllus assimilis) and one arachnid pest mite (Tetranychus urticae Koch). Results revealed that the maximum population of thrips and mites was observed on August 23, 2005 with 1.537±0.031 per leaf and July 6, 2005 with 3.271±0.09 per leaf, respectively. The population of field cricket differed significantly during crop season and reached its peak during the initial stage of crop growth on June 14, 2005, i.e., 0.873±0.014 per plant at the temperature and relative humidity of 32°C and 54%, respectively, while the minimum population was noted on August, i.e., 0.710±0.010 per plant. Present studies conclusively document the correlation of weather factors and insect pest population. Temperature had a negative and significant correlation with thrips (r = −0.860) and a positive and significant correlation with mites (r = 0.606) and field cricket (r = 0.439). However, the relative humidity displayed a positive and significant correlation with thrips (r = 0.569), a negative non-significant correlation with mites (r = −0.313), and a significant negative correlation with field cricket (r = −0.770).     

土耳其斯坦叶螨对阿维菌素和哒螨灵抗药性机理及抗性适合度研究

[目的]明确土耳其斯坦叶螨对阿维菌素和哒螨灵的抗药性机理和抗性适合度.[方法]在28℃条件下对土耳其斯坦叶螨敏感品系进行室内抗药性选育,选育出对阿维菌素和哒螨灵的抗性品系,组建生命表进行抗性适合度研究.并比较抗性品系和敏感品系的几种常见解毒酶的活性测定来进行抗性机理研究.[结果]土耳其斯坦叶螨对阿维菌素的抗性发展比较慢.在抗性适合度的研究中发现土耳其斯坦叶螨的两种抗性品系在发育历期、产卵量等指标跟敏感品系相比均存在不利性.并发现羟酸酯酶在两种抗性品系和敏感品系中比活力表现不明显,在抗阿维菌品系和敏感系中碱性磷酸酯酶存在差异性,这说明这种酶在解毒阿维菌素过程中起作用.谷胱甘肽S-转移酶、多功能氧化酶、酸性磷酸酯酶和碱性磷酸酯酶在抗哒螨灵品系和敏感品系中均表现差异.说明这些酶在解毒哒螨灵的过程中起作用.[结论]阿维菌素和哒螨灵的抗性与解毒酶活性的变化有关,并且在产生抗性后存在适合度不利性.     

山楂叶螨种群动态及其危害研究

１５ａ的研究结果表明：在冀中南部果产区,山楂叶螨种群消长呈单峰曲线,不同年份或同一年份不同果园的发生高峰不同,梨、桃园发生在６月下旬至７月中旬,苹果园发生在６月中旬至８月上旬。发生高峰的温湿度界限指标是旬日均温度２６．１４±２．１１℃,日均相对湿度６１．６７％±８．９２％;在发育起点温度（９．２℃）与界限指标温度范围内,种群增长与有效积温呈高度正相关,符合线性函数ｌｏｇｙ＝－３．５５７４＋２．５１９５ｌｏｇｘ,在果园和树冠内的种群空间分布属聚集型;山楂叶螨危害苹果、梨、桃树造成早期落叶的螨口指标分别是叶均３１．７９、３２．３４、１９．４７头（均指雌成螨）,叶片被害指数分别为６１．２７％、６０．０７％和５８．０１％。     

截形叶螨生物学特性的研究

截形叶螨ＴｅｔｒａｎｙｃｈｕｓｔｒｕｎｃａｔｕｓＥｈａｒａ在沧州枣区一年发生１３代,以卵在枣树树干皮缝中越冬,翌年春季（３月份）越冬卵开始孵化,初孵幼螨首先迁移到地面杂草上取食繁殖,４月下旬枣树发芽时陆续向枣树转移危害,在对其生物学特性进行系统研究的基础上,找到了该螨生活史中的薄弱环节,提出了冬季刮树皮,早春除草和在该螨上树前在树干涂粘虫胶环的无公害防治技术。     

Variation of 2-Tridecanone level in tomato plant leaflets and resistance to two mite species (Tetranychus sp.)

The wild tomato accession Lycopersicon hirsutum f. glabratum ‘PI 134417’ is a promising source of resistance to arthropods in tomato. It is self compatible and intercrosses easily with the cultivated species Lycopersicon esculentum. It is resistant to several arthropods, including spider mites, and these resistances have been related to the presence of high contents of 2-tridecanone (2-TD) and other methyl ketones in the leaves. The objective of this study was to evaluate the contribution of 2-TD concentration in the leaflets of Lycopersicon for resistance to the spider mites Tetranychus urticae (Koch, 1836) and T. ludeni Zacher, 1913. Plants of two segregating generations (F₂) were evaluated through the thumbtack bioassay (Weston & Snyder, 1990) in two different assays. Both experiments included as checks L. esculentum ‘TSWV-547’ (mite susceptible), L. hirsutum f. glabratum ‘PI 134417’ (resistant) and the interspecific hybrid F₁ (TSWV-547 × PI 134417). In the first experiment, 10 genotypes selected from F₂ (TSWV-547 × PI 134417), with contrasting 2-TD concentrations in the leaflets, were tested for resistance to T. urticae. In a second experiment, seven genotypes of the F₂ (TSWV-547 × BPX-318p1#230), also with contrasting 2-TD concentrations, were used to evaluate the resistance to T. ludeni. BPX-318p1#230 is a single plant selected from the segregating population F₂ (TSWV-547 × PI 134417) for its high 2-TD content. In both experiments, high negative correlations (r = − 0.88; − 0.91 and − 0.93 in the first experiment, and r = − 0.78, − 0.99 and − 0.96 in the second experiment) were found between the 2-TD content and average distance travelled by the spider mites after 60, 90 and 120 minutes, respectively. The level of resistance (repellency) to spider mites T. urticae and T. ludeni in the genus Lycopersicon appears to be mediated by the 2-TD levels present in the tomato leaflets. The similar results of both experiments showed that selection for high 2-TD content in leaflets can lead to genetic improvement in the direction of increased levels of spider mite resistance in tomato. This revised version was published online in August 2006 with corrections to the Cover Date.     

截形叶螨雌成螨应对高温胁迫的转录组分析

为明确截形叶螨Tetranychus truncatus雌成螨应对热胁迫的差异表达基因，采用Illumina HiSeq 4000进行转录组测序。结果表明，截形叶螨雌成螨热胁迫后共检测到17 577个差异基因，其中12 831个上调，4 746个下调。GO功能富集发现，雌成螨热胁迫后的差异基因主要富集于细胞过程、催化活性和细胞，KEGG通路富集分析发现，差异基因主要富集在代谢途径和溶酶体等。从转录组测序数据中筛选出与高温存在关联的抗氧化酶和热激蛋白等基因。采用RT-qPCR技术检测这些基因在截形叶螨雌成螨上的表达特征，发现17条基因的上下调趋势与转录组测序结果一致。这为后续深入研究截形叶螨与热胁迫相关基因的功能奠定了基础。     

乙唑螨腈亚致死剂量对二斑叶螨解毒酶系的影响

为明确乙唑螨腈对二斑叶螨(Tetranychus urticae Koch)体内解毒酶系的影响，采用叶片浸渍法获得乙唑螨腈对二斑叶螨的毒力回归方程，并计算出亚致死浓度LC₁₀、LC₃₀后分别处理二斑叶螨，分析60 h其体内羧酸酯酶（CarE）、谷胱甘肽-S-转移酶（GSTs）和多功能氧化酶（MFO）的比活力、米氏常数K_M及最大反应速率V_max的变化情况。结果表明：乙唑螨腈亚致死浓度对二斑叶螨体内CarE、GSTs和MFO的活性均产生诱导，且随着浓度的提高诱导增强。其中CarE的LC₁₀、LC₃₀活性最大值均出现在24 h，分别是对照的1.46、1.85倍，GSTs与MFO经LC₃₀处理后于12 h达到最大，分别是对照的1.24、1.51倍，经LC₁₀处理后最大值出现于24 h、36 h，分别是对照的1.26、1.61倍，3种解毒酶活性均随时间的延长而表现出先上升后下降的趋势。动力学参数方面，CarE的K_M值显著减小，V_max值显著增大，而GSTs和MFOs的K_M值均增大，V_max均减小，说明三者皆参与了代谢乙唑螨腈，但CarE起主导作用。因此，药剂使用时建议加入抑制CarE活性的助剂，或与抑制CarE活性的药剂混用，以提高乙唑螨腈的使用寿命和防治效果。