Effect of plant nutrition on aphid size,prey consumption,and life history characteristics of green lacewing

Plant quality can directly and indirectly affect the third trophic level. The predation by all the instars of green lacewing, Chrysoperla carnea （S.） （Neuroptera： Chrysopidae） on the cereal aphids, Rhopalosiphum padi （L.）, and Sitobion avenae （F.） at varying nitrogen fertilizer levels was calculated under laboratory conditions. Wheat plants were grown on four nitrogen fertilizer levels and aphids were fed on these plants and subsequently offered as food to the C. carnea. Aphid densities of 10, 30, and 90 were offered to first, second, and third instar larvae of green lacewing. Increased nitrogen application improved nitrogen contents of the plants and also the body weight of cereal aphids feeding on them. Aphid consumption by green lacewings was reduced with the increase in nitrogen content in the host plants of aphids. Predation of both aphid species by first, second, and third instars larvae of C. carnea was highest on aphids reared on plants with the lowest rate of fertilization, suggesting a compensatory consumption to overcome reduced biomass （lower aphid size）. Total biomass devoured by C. carnea on all nitrogen fertilizer treatments was not statistically different. Additionally, the heavier host prey influenced by the plant nutrition had an effect on the life history characteristics of green lacewings. The larval duration, pupal weight, pupal duration, fecundity, and male and female longevity were significantly affected by the level of nitrogen fertilization to the aphid＇s host plants, except for pupal duration when fed on S. avenae. This study showed that quantity of prey supplied to the larvae affects the prey consumption and thereafter the life history characteristics of green lacewings.     

Ethyl acetate: a possible alternative for anaesthetizing insects

In order to anaesthetize insects in a laboratory, chilling and application of diethyl ether and carbon dioxide are commonly used. However none of the above methods is problem free. In particular, the use of diethyl ether, despite its simplicity, is now limited due to its poor safety. In our research, we evaluated ethyl acetate as an alternative anaesthetic substance. The effects of ethyl acetate anaesthesia were compared with those produced by carbon dioxide on adult green lacewings (Neuroptera: Chrysopidae). The biological parameters measured were longevity and fecundity. No significant differences appeared between the two treatments and the control. Although further research is necessary, the use of ethyl acetate proves to be very promising and presents a valid alternative to the use of diethyl ether and, in many cases, also to carbon dioxide and chilling.     

温度对中华通草蛉捕食麦长管蚜的影响

为明确温度对中华通草蛉 Chrysoperla sinica 捕食麦蚜能力的影响,充分发挥其控害潜能,本研究利用年龄-龄期两性生命表方法,研究了5个温度下(16℃、19℃、22℃、25℃、28℃)中华通草蛉幼虫对麦长管蚜 Sitobion avenae 的捕食能力。结果发现,1龄幼虫在19℃条件下捕食量最高,16℃条件下捕食量最低,且差异显著。2龄幼虫不同温度处理间捕食量均无显著性差异,3龄幼虫捕食麦长管蚜数量则随处理温度的提高而显著降低,而幼虫期总捕食量除28℃在不同温度间均无显著性差异。2龄幼虫平均捕食率高于1龄幼虫,但显著低于 3龄幼虫。年龄-龄期捕食率结果说明,温度升高缩短了幼虫发育时间,但提高了其捕食能力;虽然不同温度处理总捕食量不变,但高温缩短了幼虫捕食所消耗的时间。22℃条件下中华通草蛉雌成虫期长(96.63 d),产卵期长(55.36 d),繁殖力强(310.36),平均世代周期( T )短(48.99 d),容易产生世代重叠现象;内禀增长率( r )和周限增长率(λ)显示中华通草蛉种群呈正增长趋势。研究结果对于春季田间释放中华通草蛉防治麦长管蚜具有一定参考价值。     

Inundative field releases and evaluation of three predators for Bemisia tabaci (Hemiptera: Aleyrodidae) management in three vegetable crops

Abstract The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), is a global pest on numerous crops, including vegetables. Weekly inundative releases of a coccinellid predator (Coccinella undecimpunctata L. [Coleoptera: Coccinellidae]), a common green lacewing predator (Chrysoperla carnea Stephen [Neuroptera: Chrysopidae]), and a mirid predator (Macrolophus caliginosus[Wagner][Hemiptera: Miridae]) were independently made in three vegetable crops (cabbage [Brassica oleracea var. capitata L.], cucumber [Cucumis sativus L.], and squash [Cucurbita pepo L.]) for the management of the sweetpotato whitefly. Approximately 1 million to 2.5 million larvae or nymphs of each predator were released in the vegetable crops during 20 weeks. Whitefly populations were reduced by ≈ 25%–45% during most of the season in each crop where each predator was released. The effect of each predator was similar on whitefly population reduction. Late in the season (October) when whitefly populations were low, generally no benefit was obtained from releasing the predators. Numbers of predators recovered during sampling in all crops were greatest for C. carnea, but this corresponded with the fact that more individuals of this predator were released than any other predator in the experiment. These results help define the utility of these natural enemies for managing B. tabaci in vegetable crops.     

中华结缕草(Zoysia sinica Hance)组织培养和再生植株研究

以中华结缕草(Zoysia sinica Hance)成熟种子为外植体在附加2．5mg／L2,4-D、0．25mg／L 6-BA和1～2mg／L VB1的改良MS培养基(MSm)上愈伤组织的诱导率最高为43．0％。愈伤组织的最佳继代培养基为MSm附加0．1mg／L 6-BA和2．0mg／L 2,4-D。在无生长调节物质的MS培养基(MS0)上,外观呈白色到淡黄色、含有密实颗粒的愈伤组织再生率为30％～60％。     

The local distribution of highly divergent mitochondrial DNA haplotypes in toque macaques Macaca sinica at Polonnaruwa, Sri Lanka

Surveys of mitochondrial DNA (mtDNA) variation in macaque monkeys have revealed extremely high levels of intraspecific divergence among haplotypes. One consistent pattern that has emerged from these studies is that divergent haplotypes are geographically segregated so that sampling a few matrilines from a given region shows them to be identical, or a closely related subset of haplotypes. Geographically structured mtDNA variation has also been commonly observed in other taxa. In this study, haplotype variation and distribution are studied in detail within a local population of toque macaques. The results show that highly divergent haplotypes, differing by 3.1% in their nucleotide sequences, coexist in this population and that they may be spatially segregated even on this micro-geographic scale. Furthermore, these differences are maintained between social groups that exchange male migrants, and thus nuclear genes, frequently.     

Mobility of three generalist predators is greater on cabbage with glossy leaf wax than on cabbage with a wax bloom

Adult coccinellids Hippodamia convergens Guerrin-Menneville, adult minute pirate bugs Orius insidiosus (Say), and larval lacewings Chrysoperla carnea (Stephens) have been reported to more effectively reduce populations of Plutella xylostella (L.) (Plutellidae: Lepidoptera) larvae on a cabbage with glossy surface waxes than on a standard cabbage variety. To examine the mechanisms, the behavior of each predator species was quantified on the two cabbage types. All three predators spent less time walking on the standard variety and more time in other activities, including grooming and scrambling (ineffective forward locomotion). In addition, walking by each predator was distributed more evenly among the parts of the leaf on the glossy cabbage than on the standard variety. In small enclosures, C. carnea and O. insidiosus found and attacked individual first instar P. xylostella more quickly on the glossy cabbage. Scanning electron micrographs showed debris, probably wax, on the tarsae of C. carnea and O. insidiosus that had walked on the standard variety, but not on those that had walked on glossy cabbage. H. convergens tarsae did not accumulate debris on either cabbage type. Predator mobility and effectiveness were apparently impeded by wax crystals, which are present only on the standard variety. This mechanism can explain the greater effectiveness of these generalist predators against P. xylostella larvae on glossy vs normal-wax cabbage.     

Caterpillar‐induced plant volatiles attract conspecific herbivores and a generalist predator

Plants release volatiles in response to caterpillar feeding that attracts natural enemies of the herbivores, a tritrophic interaction which has been considered to be an indirect plant defence against herbivores. On the other hand, the caterpillar‐induced plant volatiles have been reported to either repel or attract conspecific adult herbivores. This work was undertaken to investigate the response of both herbivores and natural enemies to caterpillar‐induced plant volatiles in apple orchards. We sampled volatile compounds emitted from uninfested apple trees, and apple trees infested with generalist herbivore the pandemis leafroller moth, Pandemis pyrusana (Lepidoptera, Tortricidae) larvae using headspace collection and analysed by gas chromatography/mass spectrometry. Infested apple trees uniquely release six compounds (benzyl alcohol, phenylacetonitrile, phenylacetaldehyde, 2‐phenylethanol, indole and (E)‐nerolidol). These compounds were tested on two species of herbivores and one predator in apple orchards. Binary blends of phenylacetonitrile + acetic acid or 2‐phenylethanol + acetic acid attracted a large number of conspecific male and female adult herbivores. The response of pandemis leafroller to herbivore‐induced plant volatiles (HIPVs) was so pronounced that over one thousand and seven hundred conspecific male and female adult herbivores were caught in traps baited with HIPVs in three‐day trapping period. In addition, significantly higher number of male and female obliquebanded leafroller, Choristoneura rosaceana (Lepidoptera, Tortricidae), was caught in traps baited a binary blend of 2‐phenylethanol + acetic acid, or a ternary blend contains 2‐phenylethanol and phenylacetonitrile + acetic acid. This result challenges the current paradigm hypothesized that HIPVs repel herbivores and question the indirect defensive function proposed for these compounds. On the other hand, a ternary blend of phenylacetonitrile and 2‐phenylethanol + acetic acid attracted the largest numbers of the general predator, the common green lacewing, Chrysoperla plorabunda. To our knowledge, this is the first record of the direct attraction of conspecific adult herbivores as well as a predator to the caterpillar‐induced plant volatiles in the field.     

出露基岩生境典型植物树干液流对自然降水和连续干旱的响应特征

以西南喀斯特地区常见的出露基岩生境为研究对象,针对该类生境典型乔木类植物菜豆树和圆叶乌桕,应用TDP热扩散探针技术,结合遮雨试验,分析了植物树干液流对自然降水和连续干旱的响应特征.结果表明:在生长季不同时期,降水后2树种液流密度较降水前均有一定程度的升高,但始终呈现落叶乔木圆叶乌桕高于半落叶乔木菜豆树的特征;连续2个月遮雨条件下,2树种液流密度均无明显降低的趋势,表明2树种均不依赖受近期降水主导的水源;通过对降水前后及连续干旱条件下2树种液流密度与环境因子的拟合关系研究发现,气象因素差异对水分环境变化条件下植物蒸腾耗水的影响较小.自然降水和短时期的连续干旱并未显著改变2树种的蒸腾耗水特征,这可能与出露基岩生境特殊的水分蓄持环境和乔木类植物依赖相对稳定的深层水源有关.