Effect of black bean aphid, Aphis fabae, on transpiration, stomatal conductance and crude protein content of faba bean

This study was initiated to investigate effects of damage by 0, 5 and 10 aphids/plant on the physiology of faba bean plants throughout different feeding periods and at two plant development stages. Immediately following removal of Aphis fabae, measurements showed 84–229% increase in transpiration rate. These changes were proportional to the number of aphids and infestation duration. Injury by A. fabae caused the stomatal conductance to be much higher in the leaves of infested plants. Leaf stomatal conductance of the infested plants increased significantly by 51–224% depending on initial aphid densities and feeding intervals. This increase was proportional to the infestation level for each date. Length of infestation period and plant growth stage seemed to have no clear effect on stomatal apertures. Aphid feeding caused a damage of about 7–33% of crude protein levels in the leaf tissue. This reduction increased with increasing infestation levels and time, except for 28‐day‐old plants on 28 days. The physiological effects of aphid feeding on water vapour and chemical composition of damaged leaves are particularly serious when the population is high.     

Diurnal pattern of aphid feeding and its effect on cotton leaf physiology

Cotton aphid (Aphis gossypii G.) populations seemed to fluctuate over the past years in cotton (Gossypium hirsutum L.) perhaps as a result of excessive use of insecticides for controlling more problematic pests. Contradictory plant responses have been observed depending upon the aphid/plant system, and it is unclear if cotton aphids, abiotic stress or both are responsible for cotton yield reduction in aphid-infested fields. Our objectives were to investigate the diurnal changes in the physiology of cotton leaves following aphid herbivory, and the diurnal pattern of aphid feeding. The experiment was conducted in a growth chamber using the cotton cultivar ‘Stoneville 474’. Leaves of the same age and size were infested with wingless adults plus nymphs. Cotton aphids were allowed to increase in numbers without restriction for 9 days, after which the amounts of carbohydrates in aphid-honeydew, and the number of honeydew droplets excreted per aphid were measured. Photosynthetic rates, dark respiration rates and foliar non-structural carbohydrates were measured. The amount of individual carbohydrates found in the honeydew was significantly different with time. The total amount of carbohydrates excreted per aphid within a 24-h period averaged 2.5 μg. The number of honeydew droplets excreted per aphid varied significantly from time to time period. Cotton aphids did not significantly alter photosynthesis or respiration rates or non-structural carbohydrates on leaves. Aphid populations of approximately 300 per leaf on the 9th day of infestation did not appear to significantly alter the physiology of cotton leaves.     

Short-term effects of aphid feeding on photosynthetic CO2 exchange and dark respiration in legume leaves

Net CO₂ exchange rates and dark respiration rates were determined for single attached legume leaves (leaflets) after 6 to 9 days of aphid infestation. Plant-aphid combinations used were broad bean ( Vicia faba L. cv. Aquadulce) and cowpea [ Vigna unguiculata (L.) Walp. cv. Caloona)] infested with cowpea aphids ( Aphis craccivora Koch) and broad bean and garden pea ( Pisum sativum L. cv. Victory Freezer) infested with pea aphids [ Acyrthosiphon pisum (Harris)]. Leaves from all aphid-infested plants had significantly greater net CO₂ exchange rates in the light than their respective controls and rates of dark respiration of leaves from infested cowpea and garden pea were also significantly greater than those of controls. Dark respiration, as a percentage of net CO₂ exchange rates in the light, was greater in aphid-infested than in control plants. When the mean net daily carbon gain was calculated for the leaves of each plant-aphid combination, leaves from aphid-infested plants had the greatest gain. It is proposed that net CO₂, exchange rates increased due to increased sink demand and dark respiration rates increased to meet the increased energy requirements of phloem loading and cellular maintenance associated with aphid feeding. The apparent compensatory carbon gain of infested leaves was consumed by the aphids.     

Evaluation of induced responses, insect population growth, and host-plant fitness may change the outcome of tests of the preference-performance hypothesis: a case study

The preference‐performance hypothesis predicts that insect preference should correspond to host suitability for offspring development. We studied the pattern of within‐plant preference in the aphid Sipha flava and its consequences for offspring performance on the host‐plant Sorghum halepense, regarding the role of induced responses of plants to aphid feeding. The consequences of within‐plant preference on aphid population growth and host‐plant traits were also evaluated. Our results showed that winged and wingless aphids preferred to settle on mature rather than young leaves. In contrast, aphid individual growth rate was higher on young leaves when compared with mature leaves, suggesting that the outcome of this test rejected the preference‐performance hypothesis. However, the inclusion of the factor ‘previous aphid infestation’ changed the outcome from a maladaptive choice to a neutral one. Thus, individual growth rates of S. flava increased when aphids developed on leaves that had been previously infested. Interestingly, aphid growth rate on previously infested leaves did not differ between young and mature leaves. On the other hand, aphid population reproductive rate was higher and the percentage of winged aphids lower when infestation occurred on mature rather than young leaves. Aphid infestation reduced plant and shoot biomass, and increased leaf mortality. These negative effects on plant traits related to plant fitness were greater when aphid infestation occurred on young leaves. Likewise, whereas infestation on mature leaves did not cause a significant reduction in the number of flowering plants compared with control plants, aphid infestation on young leaves did reduce the number of plants at the flowering stage. Consequently, if both the reproductive rate of aphids in the mid‐term, and host‐plant fitness are taken into account, the results indicate that aphid preference for mature leaves may be an adaptive choice, thus supporting the preference‐performance hypothesis.     

Direct and Indirect Impacts of Infestation of Tomato Plant by Myzus persicae (Hemiptera: Aphididae) on Bemisia tabaci (Hemiptera: Aleyrodidae)

The impacts of infestation by the green peach aphid (Myzus persicae) on sweetpotato whitefly (Bemisia tabaci) settling on tomato were determined in seven separate experiments with whole plants and with detached leaves through manipulation of four factors: durations of aphid infestation, density of aphids, intervals between aphid removal after different durations of infestation and the time of whitefly release, and leaf positions on the plants. The results demonstrated that B. tabaci preferred to settle on the plant leaves that had not been infested by aphids when they had a choice. The plant leaves on which aphids were still present (direct effect) had fewer whiteflies than those previously infested by aphids (indirect effect). The whiteflies were able to settle on the plant which aphids had previously infested, and also could settle on leaves with aphids if no uninfested plants were available. Tests of direct factors revealed that duration of aphid infestation had a stronger effect on whitefly landing preference than aphid density; whitefly preference was the least when 20 aphids fed on the leaves for 72 h. Tests of indirect effects revealed that the major factor that affected whitefly preference for a host plant was the interval between the time of aphid removal after infestation and the time of whitefly release. The importance of the four factors that affected the induced plant defense against whiteflies can be arranged in the following order: time intervals between aphid removal and whitefly release > durations of aphid infestation > density of aphids > leaf positions on the plants. In conclusion, the density of aphid infestation and time for which they were feeding influenced the production of induced compounds by tomatoes, the whitefly responses to the plants, and reduced interspecific competition.     

棉蚜对寄主的选择及寄主专化型研究

采用叶片选择法,生命表及EPG技术研究了棉蚜对寄主植物的选择和专化性,结果表明,棉花上生长的棉蚜对棉花,西葫芦和西瓜叶片均具有强选择性,而对黄瓜和南瓜选择性弱,西瓜,南瓜和黄瓜上生长的棉蚜对其原寄主选择性强,而对棉花选择性弱,棉花上的棉蚜转接到黄瓜和南瓜上,其存活率和繁殖力极低,棉蚜的取食行为在黄瓜和马铃薯,黄瓜和棉花之间存在明显的寄主专化型,黄瓜与棉花上的棉蚜相互转接均难成功,而黄瓜和马铃薯上的棉蚜转移具有不对称性。     

Effects of Russian wheat aphid infestation on barley plant response to drought stress

The influence of Russian wheat aphid ( Diuraphis noxia Mordvilko) infestation on the response of barley ( Hordeum vulgare L. ev Hazen) plants to drought stress was investigated. Fourteen-day-old plants were infested with eight apterous adult aphids, which were removed 7 days later with systemic insecticide. Leaves previously infested with aphids had lower relative water content, reduced stomatal conductance, more negative water potential, lower levels of chlorophyll and higher levels of amino-N, proline and glycinebetaine than corresponding leaves from uninfested plants. When water was withheld for a period of 7 days after aphids were removed, the relative water content of previously infested plants dropped steadily from 0.89 to 0.60, while the relative water content of uninfested plants remained at about 0.94 for the first 4 days of the drought stress period followed by a steady drop to about 0.77 by the end of the drought stress period. Leaf water potentials dropped steadily during the drought stress period in both previously infested (-1.14 to -1.91 MPa) and unin-fested (-0.54 to -1.52 MPa) plants. Analysis of glycinebetaine and proline levels at the end of the drought stress period indicated that leaves of previously infested plants accumulated lower levels of these solutes than leaves from uninfested plants. Upon alleviation of drought stress, plants previously infested with aphids showed little increase in dry weight while younger leaves and tillers from uninfested plants showed large increases. It is concluded that Russian wheat aphids cause drought-stress symptoms in leaves of infested plants even in the presence of ample root moisture. The observations of low levels of glycinebetaine and proline present in leaves after water was withheld from roots and lack of leaf growth upon alleviation of drought stress in previously-infested plants, suggest that aphid infestation limits the capacity of barley plants to adjust successfully to drought stress.     

Evaluation of Lecanicillium longisporum, Vertalec for simultaneous suppression of cotton aphid, Aphis gossypii, and cucumber powdery mildew, Sphaerotheca fuliginea, on potted cucumbers

The commercial preparation of Lecanicillium longisporum, Vertalec^® was evaluated for simultaneous suppression of cotton aphid and cucumber powdery mildew on potted cucumber plants. Vertalec was applied onto cucumber plants that had been infested with either cotton aphid, spores of Sphaerotheca fuliginea or both. Irradiation-inactivated Vertalec (II Vertalec) was also applied to an identical series of cucumber plants as a control. The Vertalec was highly pathogenic against adult aphids with an LT₅₀ of 6.9 days. II Vertalec did not affect aphid survival. Application of either active or II Vertalec significantly suppressed spore production of S. fuliginea compared to the water control. For dual control assays, Vertalec applications were made one day after infestation of both aphid and S. fuliginea onto potted cucumbers. Fifteen days after the Vertalec treatments, the numbers of surviving aphids and the production of powdery mildew spores were significantly reduced compared with the water control. The presence of aphids also suppressed S. fuliginea spore production. Our results suggest the potential of a dual role for Vertalec as a microbial control agent of aphids and powdery mildew in cucumber.     

棉蚜寄主专化型及其形成的行为机理

通过生活在甜瓜和棉花上的棉蚜Aphisgossypii Glover的行为,研究棉蚜的寄主专化型及其形成的行为机理。生物学观察显示： 两类棉蚜在寄主植物相互交换以后,定居数显著减少,棉花蚜型棉蚜的繁殖系数及若虫存活率显著下降,说明棉蚜存在甜瓜蚜型和棉花蚜型两种寄主专化型。通过刺探电位技术研究棉蚜的取食行为,以探索其寄主专化型形成的行为机理。结果表明： 甜瓜蚜型棉蚜在棉花上的取食行为容易被中断,但其口针定位韧皮部的能力并没有显著削弱;而棉花蚜型棉蚜在甜瓜上的取食行为受到更大的影响,口针无法顺利定位至韧皮部,并在2 h内根本无法在筛管内取食。生物学观察和EPG取食行为分析都显示： 与甜瓜蚜型棉蚜相比,棉花蚜型棉蚜对寄主的要求更严格-寄主专化程度更高,对寄主的利用率更高。     

Impact of transgenic cotton plants on a non-target pest, Aphis gossypii Glover

Abstract.  1. Transgenic crops have shown great promise for the control of target pest insects, but in some cases they can also influence non-target species. This study investigated the impact of Bt and Bt+CpTI transgenic cottons on the non-target cotton aphid, Aphis gossypii Glover, by comparing life-table parameters, feeding behaviour, and the fluctuating asymmetry of morphological traits of aphids reared on transgenic cotton and those on untransformed control plants.
2. Aphids on the Bt+CpTI cotton showed a shorter reproductive duration and maximum lifespan, lower survival rates and potential maximum fecundity, and an earlier occurrence of peak daily mortality in the first or second generation. However, the aphid population soon developed fitness and overcame the negative effect in the second or third generation. The aphids on the Bt cotton had significantly longer reproductive durations in the first generation, higher survival rates in the third generation, and apparently larger potential maximum fecundity in all three generations.
3. The percentages of accumulated duration of feeding waveforms E1 and E2 were significantly lower in aphids on the Bt+CpTI cotton than in those on the Bt or control cotton, whereas the frequencies of moving and finding feeding sites, and probe behaviour were significantly higher.
4. Fluctuating asymmetry in three morphological characters of aphids reared on transgenic and control cotton was detected. The fluctuating asymmetry value of the third segment of antenna in aphids on Bt+CpTI cotton was significantly higher than that of aphids on Bt or control cotton. Based on the fluctuating asymmetry value, the stress of cotton on the aphids could be ranked as Bt+CpTI cotton > Bt cotton > control cotton.     

Local and systemic responses induced by aphids in Solanum tuberosum plants

The aphids Macrosiphum euphorbiae (Thomas) and Myzus persicae (Sulzer) (Homoptera: Aphididae) are serious pests of potato (Solanum tuberosum L.) (Solanaceae), notably in transmitting several plant viruses. Heterospecific interactions may occur between these two species as they are often seen at the same time on the same potato plant in the field. As aphid infestation is known to induce both local and systemic changes, we conducted experiments to determine the effect of previous infestation on probing behaviour and feeding‐related parameters. We used the DC electrical penetration graph technique to characterize the influence of previous infestation by conspecific M. persicae or by heterospecific Ma. euphorbiae on M. persicae feeding behaviour at both local and systemic levels, i.e., on previously infested leaves and on non‐previously infested leaves of infested plants, respectively. Conspecific and heterospecific infestation led to similar modification of M. persicae feeding activities. However, the effects of previous infestation occurring at the local level were opposite to those observed at the systemic level. Myzus persicae food acceptance was slightly enhanced on previously infested leaves, whereas it was inhibited on non‐infested leaves of infested plants, which indicated an induced resistance mechanism. Our results advance the understanding of the mechanisms involved in aphid–host plant acceptance and colonization processes on potato plants in conspecific and heterospecific situations.     

Effects of leaf and sap feeding insects on photosynthetic rates of goldenrod

Summary Herbivory can alter the balance between sources and sinks within a plant, and changes in the source-sink ratio often lead to changes in plant photosynthetic rates. We investigated how feeding by three insect herbivores affected photosynthetic rates and growth of goldenrod (Solidago altissima). One, a phloem-sap feeding aphid (Uroleucon caligatum), creates an additional sink, and the other two, a leaf-chewing beetle (Trirhabda sp.) and a xylem-sap feeding spittlebug (Philaenus spumarius) both reduce source supply by decreasing leaf area. Plants were grown outside in large pots and insects were placed on them at predetermined densities, with undamaged plants included as controls. All insects were removed after a 12-day feeding period. We measured photosynthetic rates both of damaged leaves and of undamaged leaves that were produced after insect removal. Photosynthetic rates per unit area of damaged leaves were reduced by spittlebug feeding, but not by beetle or aphid feeding. Conductance of spittlebugdamaged leaves did not differ from controls, but internal carbon dioxide concentrations were increased. These results indicate that spittlebug feeding does not cause stomatal closure, but impairs fixation within the leaf. Effects of spittlebug feeding on photosynthetic rates persisted after the insects were removed from the plants. Photosynthetic rates per unit area of leaves produced after insect removal on spittlegug-damaged plants were lower than control levels, even though the measurements were taken 12 days after insect removal. The measurement leaf on spittlebugdamaged plants was reduced in area by 27% relative to the controls, but specific leaf area (leaf area/leaf weight) was increased by 18%. Because of the shift in specific leaf area, photosynthetic rates were also examined per unit leaf weight, and when this was done there were no significant differences between control and spittlebug-damaged plants. Beetle and aphid feeding had no effects on the photosynthetic rate of the leaves produced after insect removal. Plant relative growth rates (in terms of height) were reduced by spittlebugs during the period that the insects were feeding on the plants. Relative growth rates of spittlebug-damaged plants were increased above control levels after insect removal, but these plants were still shorter than controls 17 days after insect removal. Beetles and aphids did not affect plant relative growth rates or plant height. Feeding by both spittlebugs and beetles reduced leaf area, and the effect of the spittlebug was more severe than that of the beetle. These results show that effects of herbivory on photosynthetic rates cannot be predicted simply by considering changes in the source-sink ratio, and that spittlebug feeding is more damaging to the host plant than beetle or aphid feeding.     

The effect of Brevicoryne brassicae on leaf area, dry matter distribution and amino acids of the Brussels sprout plant

Twenty-six direct or derived criteria were assessed, eight wk after infestation, of the effect of an initial inoculum of 0, 5, 25 or 50 Brevicoryne brassicae on the growth and dry matter distribution of Brussels sprout plants. Twenty-four of these criteria showed significant (P > 0.05) effects of aphid infestation, though increasing aphid infestation above 5/plant had little further effect. Total fresh and dry weight (as well as of the components — leaves, stems and roots) was reduced by 25–730 with infestation, particularly so the root. The number of leaves as well as individual leaf area was reduced, and leaves on infested plants were less efficient assimilators. This could be explained by the drain on assimilates caused by the aphids, the leaf curling and the reduced density of stomata. The latter was also considered to account partly for the increased moisture content of infested plants. There was a general reduction in the concentration of leaf amino acids.     

The effects of nitrogen and sulphur nutrition on the response of Brussels sprout plants to infestation by the aphid Brevicoryne brassicae

The effects of two levels each of nitrogen and sulphur nutrition and of infestation by Brevicoryne brassicae on the growth of Brussels sprout plants were studied in factorial experiments. All the plants receiving high nitrogen treatments grew more rapidly than those with low, but in infested plants the improvement in growth at the higher levels of nitrogen was offset by the increased size of aphid populations. Low sulphur nutrition increased the growth of plants receiving high nitrogen and of the aphids feeding on them. Leaf diffusive resistances and chlorophyll concentrations were greater with high nitrogen, but were significantly lowered by infestation in all nutrient treatments. Infestation decreased leaf total nitrogen concentration at the sites of feeding, but effects on soluble nitrogen were not significant. Removal of aphids 72 days after initial infestation did not cause marked plant recovery during the next 22 days. It is concluded that the benefits of increased yield resulting from high nitrogen levels must be balanced against the greater potential for damage by aphids.     

Spectral response of cotton aphid- (Homoptera: Aphididae) and spider mite- (Acari: Tetranychidae) infested cotton: controlled studies

Remote sensing is a precision tool that can detect plant health. Ground-based methods in small-scale experiments were used to explore the applicability of this technology for detection of arthropod-damaged cotton and to find useful indices or wavelengths for detecting arthropod-damaged cotton. Individual leaves of greenhouse-grown cotton plants and cotton plants in the field were infested with populations of cotton aphids, spider mites, and aphids + mites. Several sets of reflectance measurements were collected from the adaxial surface of the leaves at various intervals after infestation using a portable hyperspectral spectrometer with an integrating sphere or a contact probe. Vegetation indices were calculated from the reflectance values; these indices and the raw reflectance values, represented by narrow wavelength bands, were tested to see if arthropod damaged cotton could be distinguished from healthy cotton. Results indicated that it was possible to detect cotton aphid- and spider mite-damaged leaves by tracking the spectral changes in the leaf, although the damage type of each arthropod could not be distinguished spectrally. In addition, spider mite- and aphid-infested cotton leaves increased reflectance in the near infrared wavelength at approximately 850 nm in comparison to uninfested leaves.     

施钾提高蚜害诱导的小麦茉莉酸含量和叶片相关防御酶活性

研究表明,施钾能够提高作物对蚜虫的抗性,但其机理尚不明确。试验采用营养液培养的方法,设置2 mmol/L和0.005mmol/L KCl两个钾浓度,分析不同钾水平培养下的小麦植株在蚜虫为害后,体内茉莉酸(JA)和水杨酸(SA)的含量和脂氧合酶(LOX)、多酚氧化酶(PPO)、苯丙氨酸解氨酶(PAL)和过氧化物酶(POD)等防御酶活性的变化。结果表明,低钾胁迫显著降低了小麦体内JA和SA的含量,并且诱导LOX和POD酶活性增强,但是对PPO和PAL酶活性没有显著影响。蚜虫为害48 h后,高钾小麦体内JA含量显著高于低钾植株,而SA含量没有明显变化。高钾显著提高了蚜虫为害后小麦叶片中的LOX、PAL、PPO和POD酶活性,而低钾小麦体内4种酶的活性在整个虫害调查期间均没有显著变化。研究表明,充足供钾能够显著提高小麦受到蚜虫为害后体内茉莉酸含量,激活其体内的JA信号传导途径,从而提高防御酶活性,增强其对蚜虫的抵御能力。     

降水和灌溉对麦双尾蚜种群数量的影响

该文探讨了1989～1996年新疆塔城市麦双尾蚜Diuraphis noxia Mordvilko 年度间种群数量和降水量的关系,利用降水模拟方法分析降水因素对麦双尾蚜种群数量的影响,并调查了田间不同灌溉水平的植株上麦双尾蚜的数量。结果显示：6月下旬春麦田麦双尾蚜种群数量和当年4月份和5月份的降水总量存在明显负相关性(r＝-0.92),与5月上旬和6月中旬降水总量存在明显负相关性(r＝-0.78),并且与上年7月中下旬降水量存在明显正相关性(r＝0.67),这些相关性表明4～5月份降水对麦双尾蚜种群增长不利,5～6月上旬降水对麦双尾蚜从冬麦迁入春麦不利,7月降水有利于麦双尾蚜种群增长,并依据4～5月降水量(X)和春麦田麦双尾蚜数量?建立了回归方程r＝4.9-0.048X。田间和实验室内模拟降水可以明显降低麦双尾蚜种群数量。田间相对干旱地段麦双尾蚜数量明显高于湿润地段,并且干旱地段麦双尾蚜被菜蚜茧蜂Diaeretiella rapae Mintosh寄生的百分率相对较低。     

Dynamic changes in photosynthesis and chlorophyll fluorescence in Nicotiana tabacum infested by Bemisia tabaci (Middle East–Asia Minor 1) nymphs

Bemisia tabaci Middle East–Asia Minor 1 (MEAM1) is a worldwide pest. To determine whether MEAM1 nymphs produce the same symptoms in different host plants, we measured the plant growth and chlorophyll content of tobacco and cotton plants that were infested by MEAM1 nymphs. Furthermore, to investigate the spatial and temporal changes in photosynthesis caused by MEAM1 nymphs, the net photosynthetic rate (Pn) and chlorophyll a fluorescence of local and systemic tobacco leaves were assayed at 8, 11, 14, and 20 days after MEAM1 adult removal, which represent the stages of 1st, 2nd, 3rd, and 4th instar nymphs, respectively. The results showed that MEAM1 nymph infestation reduced the plant height and internode length of tobacco at 14 and 20 days, as well as the dry weight of infested and systemic tobacco leaves. However, MEAM1 nymph infestation did not affect the plant height or internode length of cotton. Also, the dry weight and chlorophyll and carotenoid content of infested and systemic leaves of cotton plants were not influenced by MEAM1 nymph infestation. However, the contents of chlorophyll a and b and carotenoids in infested tobacco leaves decreased over time; the chlorophyll a content of systemic tobacco leaves decreased at 11, 14, and 20 days. The chlorophyll and carotenoid contents in infested and systemic leaves of cotton plants were not influenced by MEAM1 nymph infestation. In addition, the Pn of infested tobacco leaves decreased at 14 and 20 days, while the Pn in systemic tobacco leaves decreased after 11 days. The greatest decrease in performance index on absorption basis (PI _ABS ) of infested and systemic tobacco leaves occurred on day 14. The fluorescence intensity at 2 ms (J peak) and 300 μs (K peak) increased on day 14, which indicates that 3rd instar nymphs caused serious damage to the primary photochemical reactions and donor side of PSII. These results suggest that MEAM1 nymph infestation had different effects on tobacco and cotton plants. The infestation caused spatial and temporal changes in photosynthesis in tobacco plants. The lower chlorophyll a content may have been related to the lower net photosynthetic rate of systemic and infested tobacco leaves. The decreased stability of the oxygen-evolving complex and the reaction center of PSII and the decrease in electron transport were the main reasons for the decrease in the level of photosynthesis in tobacco leaves caused by MEAM1 nymphs during various stages of infestation.     

Kaolin particle film associated with increased cotton aphid infestations in cotton

Highly reflective white kaolin‐based particle film was sprayed on cotton, Gossypium hirsutum L. (Malvaceae), plots in south Texas during 2004 and 2005 to observe its effect on the cotton aphid, Aphis gossypii Glover (Homoptera: Aphididae). Populations of cotton aphids on the ventral surfaces of leaves in the kaolin‐treated plots were greater than in non‐treated control plots during both years. Alate cotton aphids were attracted less to white than to other pan trap colors, and parasitism by Lysiphlebus spec. (Hymenoptera: Aphidiidae) was either unaffected or greater in the kaolin‐treated plots, hence these two factors (color and parasitism) do not explain the increased infestations in the treated plots. However, mean temperatures on the ventral surfaces of kaolin‐treated cotton leaves were cooler than those of control leaves. The observed temperature difference where cotton aphids reside on cotton leaves is a potential reason for the greater infestations in the kaolin treatment plots. Our study demonstrates that applications of kaolin can exacerbate a pest infestation in cotton.     

转Cry1Ac+Cry2Ab基因棉对棉蚜生命表参数及种群动态的影响

为研究新型转Cry1Ac+Cry2Ab基因棉对棉蚜Aphis gossypii Glover生命表参数及种群动态的影响。2010—2011年以常规棉中棉所49为对照,对新型转Cry1Ac+Cry2Ab基因棉在室内进行了生物测定和田间进行了系统的调查。结果表明,和常规棉相比,转Cry1Ac+Cry2Ab基因棉花上棉蚜的净增值率降低81.69%,差异达显著水平;内禀增长率和周限增长率分别降低65.00%和13.01%,但差异不显著;平均世代周期和种群加倍时间分别增加5.54%和154.19%,后者差异达显著水平。和常规棉相比,2010年转Cry1Ac+Cry2Ab基因棉花百株苗蚜、伏蚜和秋蚜的数量分别降低10.79%、37.18%和17.49%,差异均未达显著水平;2011年转Cry1Ac+Cry2Ab基因棉花百株苗蚜的数量增加2.03%,伏蚜和秋蚜的数量分别降低37.41%和64.03%,差异均未达显著水平。