Temperature modulation of behavioural thresholds controlling male moth sex pheromone response specificity

ABSTRACT. The response specificity of male Oriental fruit moths, Grapholita molesta (Busck) and pink bollworm moths, Pectinophora gossypiella (Saunders), to different blends and doses of pheromone is altered dramatically by temperature. When acclimated and tested in a flight tunnel at 20^oC males of both species exhibit a high degree of specificity, with peak response levels occurring to a narrow range of blend-dose combinations close to the natural blend. When tested at 26^oC, however, males exhibit a significantly lower degree of specificity, with peak response occurring to a broader range of treatments. The change in response specificity results from shifts in behavioural threshold effects influencing plume orientation and initiation of upwind flight, as well as from arrestment of upwind flight, occurring later in the flight sequence. The observed changes in male behaviour suggest that the effect of temperature is directly on neural pathways involved in the perception of odour, and not simply the result of an increase in motor activity or a significant change in the release rate of the pheromone. The results support the threshold hypothesis for pheromone perception (Roelofs, 1978) as a general principle in the Lepidoptera, but also show that the degree of response specificity can be significantly affected by temperature.     

莱阳地区梨园、桃园、混栽桃梨园梨小食心虫发生规律

为明确莱阳地区不同栽培模式下单植梨园、单植桃园、混植桃梨园的梨小食心虫Grapholitha molesta(Busck)发生规律,2009—2012年采用性诱芯法对以上果园梨小食心虫的发生规律进行探究并利用有效积温模型预测其发生代数。结果表明:梨小食心虫在莱阳地区一年可发生4代;第1³代主要发生在桃园,发生时间为4—8月上旬,第4代主要发生在梨园,发生时间为8月中下旬或9月初,为害一直可持续到10月中旬。梨小食心虫在不同寄主上发生时间不同,除第一代发生比较整齐之外,其他世代发生时间不统一,尤其是梨园。单植梨园和单植桃园的梨小食心虫都能单独完成发育世代,但数量有差异。通过比较其差异显著性,单植桃园13代主要发生在桃园,发生时间为4—8月上旬,第4代主要发生在梨园,发生时间为8月中下旬或9月初,为害一直可持续到10月中旬。梨小食心虫在不同寄主上发生时间不同,除第一代发生比较整齐之外,其他世代发生时间不统一,尤其是梨园。单植梨园和单植桃园的梨小食心虫都能单独完成发育世代,但数量有差异。通过比较其差异显著性,单植桃园1³代明显多于第4代,单植梨园第4代明显多于第13代明显多于第4代,单植梨园第4代明显多于第1³代。     

Gas chromatography column as an ambient‐temperature volatile trap

Open‐tube volatile traps have largely been shunned in favor of solid adsorbent containing traps for the collection of volatile pheromones and attractants. Solid adsorbents require large solvent rinses and glass capillaries can be difficult to maneuver for the collection of volatiles from small or hard‐to‐reach odor sources. A gas chromatograph (GC) column (DB‐1), an open‐tube glass capillary, and a SuperQ^®‐containing capillary were compared for their collection efficiencies from rubber septa and live calling insects. All three traps captured similar ratios of test compounds from septa at airflows >10 ml per min. Eluting analytes from a packed adsorbent, SuperQ, required at least 30× more solvent than was required to collect all the pheromone from the open‐tube glass capillaries, and the GC column enjoyed an additional three‐fold reduced solvent volume compared to the glass capillary. Thus, analytes could be eluted from the GC‐column trap and directly analyzed on GC without solvent evaporation. We placed glass wool ‘plugs’ in both GC columns and glass capillaries and found no volatiles in these plugs, indicating that breakthrough did not occur during 1‐h collections at 25 ml per min. We demonstrate here that at ambient laboratory temperatures, a DB‐1 GC column effectively collects Oriental fruit moth sex pheromone volatiles from a rubber septum and live pheromone‐releasing moths. Release ratios of pheromone from rubber septa are consistent with earlier reports from static air systems, whereas the release ratio of the (Z)‐8‐dodecenyl alcohol (Z8‐12:OH) from female Grapholita molesta Busck (Lepidoptera: Tortricidae) differed from published results and is likely due to different collection methods or moth‐strain origin.     

Apple and peach fruit volatiles and the apple constituent butyl hexanoate attract female oriental fruit moth, Cydia molesta, in the laboratory

Volatiles emitted from immature and mature peach and apple fruits were all attractive to mated female oriental fruit moth, Cydia molesta (Busck), in a dual choice arena. Females did not discriminate between odours emitted by these two major host plants. The same natural blends were behaviourally ineffective for virgin females. A major component of apple fruit volatiles, butyl hexanoate, also attracted female C. molesta. Mated females were attracted to two medium dosages, while virgin females responded positively to the lowest of the five dosages tested. The time course of the captures of the moths shows a diurnal activity cycle known from the field. The possible implications of a semiochemical which attracts females are discussed in the context of previous findings that gravid females may immigrate from peaches into apple orchards particularly in the later phase of the season.     

Asymmetric impacts of two herbivore ecotypes on similar host plants

1. Ecotypes may arise following allopatric separation from source populations. The simultaneous transfer of an exotic plant to a novel environment, along with its stenophagous herbivore, may complicate more traditional patterns of divergence from the plant and insect source populations. 2. The present study evaluated herbivory effects by two Cyrtobagous salviniae ecotypes on two species of Salvinia: the larger S. molesta and the smaller S. minima. Evaluations were based on relative growth rates, biomass production, coverage, and nutrient cycling in a series of complementary and comparative laboratory and outdoor tank experiments. 3. In general, the experiment results indicated that the smaller Florida ecotype of C. salviniae impacted both Salvinia species more than the larger Brazil ecotype. Herbivory, especially by the Florida ecotype, also improved water quality and accelerated nutrient cycling by increasing the rates of litterfall from the standing crops of salvinia. 4. The smaller size of the Florida ecotype may be adaptive by allowing maximal exploitation of host plants via internal larval feeding, which presumably reduces predation risk while increasing damage to the plant. These findings provide support for relying on the suppressive effects of the Florida ecotype in Florida, rather than introducing the Brazil ecotype to counter new infestations of S. molesta.     

江苏无锡梨小食心虫发生动态及性诱剂防治

利用性诱剂调查江苏无锡地区三个水蜜桃Prunus persica种植区梨小食心虫Gtapholitha molesta成虫的年发生动态,并比较不同时间挂放诱芯的诱集效果。结果表明,在无锡地区,梨小食心虫年发生5代,部分发育较快的五代幼虫在越冬前发育为成虫,但因无法找到合适的产卵场所而成为无效虫口。越冬代成虫和一代成虫发生较为整齐,可以使用性诱剂集中诱杀,但从二代成虫开始,发生呈现多个高峰,田间世代重叠明显。对梨小食心虫的性诱剂防治试验表明,在无锡地区,需高密度放置诱芯并2周更换1次诱芯方能达到防治效果。     

梨小食心虫化学感受蛋白cDNA的克隆、序列分析及原核表达

为了研究梨小食心虫Grapholita molesta化学感受蛋白（chemosensory proteins, CSPs）在化学感受系统中的作用, 本研究利用RT-PCR和RACE技术克隆到一条梨小食心虫化学感受蛋白的全长cDNA序列, 命名为GmolCSP （GenBank 登录号： JQ821389）。序列分析表明, GmolCSP开放阅读框序列为384 bp, 编码127个氨基酸残基, 预测N末端含有18个氨基酸组成的信号肽序列, 其成熟蛋白的预测分子量为12.80 kD, 等电点为8.33。该基因编码的氨基酸序列与其他鳞翅目昆虫化学感受蛋白的氨基酸序列具有较高同源性。RT-PCR结果显示, GmolCSP在梨小食心虫成虫触角、 去触角的头、 胸、 腹、 足和翅中都有表达。将GmolCSP重组到表达载体pET-32a中, 转入大肠杆菌Escherichia coli BL21（DE3）进行表达。SDS-PAGE和Western 印迹检测结果显示, 梨小食心虫化学感受蛋白基因在大肠杆菌中成功地表达出一个分子量约为29 kD的融合蛋白, 与预测的融合蛋白分子量大小一致。本研究结果为进一步研究该蛋白的分子结构和功能奠定了良好基础。     

桃园中食心虫单一性诱芯及其复合配置的诱蛾效率比较

【目的】明确两种食心虫性诱芯复合配置的诱蛾效果,提高其监测或防治效率及其绿色环保化水平,为果树生产中食心虫的高效监测和绿色防控提供科学依据。【方法】田间系统调查研究了梨小食心虫(以下简称"梨小")、桃小食心虫(以下简称"桃小")单一性诱芯及其复合配置3种处理的诱蛾效率,并利用"Y"型嗅觉仪比较研究了其间梨小雄蛾趋向性的差异。【结果】(1)梨小和桃小性单一诱芯及其复合配置对梨小均具有引诱作用,其诱蛾总量依次为8 238.33、1 451.67、8 321.67头/诱捕器,其中第1、2、3代时复合配置诱蛾量最大,越冬代和第4代时梨小单一性诱芯诱蛾量最大,而各世代桃小单一性诱芯诱蛾量均最低。梨小单一性诱芯及其复合配置均监测到5个梨小发生高峰,且峰期基本一致,但复合配置的峰日诱蛾量均较高;桃小单一性诱芯仅监测到3个梨小发生高峰,且峰日诱蛾量亦较低。(2)桃小单一性诱芯及其复合配置对桃小均具有引诱作用,其诱蛾总量依次为4.00、2.33头/诱捕器,而梨小单一性诱芯对桃小无引诱作用。(3)"Y"型嗅觉仪研究发现,梨小食心虫对梨小和桃小各单一性诱芯及其复合配置均具有趋向作用,其趋向率依次为50.67%、8.67%、53.33%。【结论】梨小和桃小单一性诱芯复合配置对梨小诱捕量有微增效作用,而对桃小诱捕量有一定干扰作用,但影响均不显著。据此,该复合配置可用于桃园中梨小和桃小的监测与防控。