Natural Enemies of the Frankliniella Complex Species (Thysanoptera: Thripidae) in Ataulfo Mango Agroecosystems

A field survey was conducted in Ataulfo mango (Mangifera indica L.) orchards in Chiapas, Mexico, with the objective of determining the natural enemies of the Frankliniella complex species (Thysanoptera: Thripidae). Seven species of this genus feed and reproduce in large numbers during the mango flowering. Two representative orchards were selected: the orchard “Tres A” characterized by an intensive use of agrochemicals directed against thrips, and the orchard “La Escondida” that did not spray insecticides. During mango flowering, five inflorescences were randomly collected every 5 d in both orchards, for a total of 18 sampling dates. Results revealed the presence of 18 species of arthropods that were found predating on Frankliniella. There were 11 species in the families Aeolothripidae, Phlaeothripidae, Formicidae, Anthocoridae and Chrysopidae; and seven species of spiders in the families Araneidae, Tetragnathidae, and Uloboridae. Over 88% of predators were anthocorids, including, Paratriphleps sp. (Champion), Orius insidiosus (Say), Orius tristicolor (White), and O. perpunctatus (Reuter). The orchard that did not spray insecticides had a significantly higher number of predators suggesting a negative effect of the insecticides on the abundance of these organisms.     

An Evaluation of Frankliniella occidentalis (Thysanoptera: Thripidae) and Frankliniella intonsa (Thysanoptera: Thripidae) Performance on Different Plant Leaves Based on Life History Characteristics

To compare the performance of Frankliniella occidentalis (Pergande) and native Frankliniella intonsa (Trybom) on cucumber and tomato leaves in laboratory, life history characters were investigated, and life tables were constructed using the method of age-stage, two-sex table life. Compared with tomato leaf, there were shorter total preoviposition period (TPOP), higher fecundity, longer female longevity, and higher intrinsic rate of increase (r) of both F. occidentalis and F. intonsa on cucumber leaf. Meanwhile, on cucumber leaf, the shorter TPOP, higher fecundity, longer female longevity, and higher value of r were found on population of F. intonsa but on tomato leaf which were found on population of F. occidentalis. From above, cucumber leaf was the preference to population development of both F. occidentalis and F. intonsa compared with tomato leaf. Nevertheless, on cucumber leaf, population of F. intonsa would grow faster than that of F. occidentalis, which was the opposite on tomato leaf. As to the population development in fields, much more factors would be taken into account, such as pollen, insecticide resistance, and effects of natural enemies etc.     

中国海南海岛小花蝽(Orius maxidentex Ghauri)的发现及生物学记述

花蝽是一类捕食性半翅目昆虫。花蝽科目前约包含70个属,其中小花蝽属（Orius Wolff, 1811）是最大的属,全世界包含约80种,中国目前有15种。小花蝽属的种类在蓟马的生物防治方面具有极大的应用前景,是生物防治领域研究和利用的热门天敌类群。目前在我国针对蓟马的有害生物综合治理及绿色防控项目中,能够应用的仅东亚小花蝽（O. sauteri）及南方小花蝽（O. strigicollis）。最近在海南发现的海岛小花蝽（Orius maxidentex Ghauri）为中国新记录种,国外分布于泰国、印度、巴基斯坦、伊朗、阿拉伯联合酋长国、苏丹、塞内加尔。本研究对海岛小花蝽的形态学特征和生物学特征进行了描述,拍摄了海岛小花蝽各虫态及生殖器特征图,并对其发育历期、捕食、交配、产卵、孵化、蜕皮、羽化及同类相食的现象进行了简单描述和研究。此外,本研究获得了海岛小花蝽线粒体细胞色素氧化酶亚基I（COI）基因序列,并提交到美国国家生物技术信息中心（GenBank登录号：OL798096）进行序列比对,分子鉴定结果表明与塞内加尔的海岛小花蝽序列高度一致。海岛小花蝽常见于青葙（Celosia argentea）、小蓬草（Conyza canadensis）等杂草,及芒果（Mangifera indica）、豇豆（Vigna unguiculata）和茄子（Solanum melongena）等作物的花及幼叶上。卵产于植物组织中,若虫阶段有5个龄期,成虫和若虫均以蓟马为食,可捕食花蓟马（Frankliniella intonsa）、黄胸蓟马（Thrips hawaiiensis）、棕榈蓟马（T. palmi）、豆大蓟马（Megalurothrips usitatus）、茶黄蓟马（Scirtothrips dorsalis）及美洲棘蓟马（Echinothrips americanus）等。海岛小花蝽在海南岛全年可见,且具有明显的种群优势,是海南蓟马害虫的重要天敌。本研究在实验室条件下,利用美洲棘蓟马（E. americanus）和大豆幼苗进行室内饲养和观察,发现海岛小花蝽在温度(25±2)℃及相对湿度75%±5%条件下,可以取食美洲棘蓟马完成世代发育,卵期(3.66±0.67)d,1龄若虫(1.72±0.65)d,2龄若虫(2.21±0.82)d,3龄若虫(2.62±0.62)d,4龄若虫(2.45±0.74)d,5龄若虫(3.21± 0.82)d。本研究凭证标本保存于中国热带农业科学院环境与植物保护研究所和中国农业大学植物保护学院昆虫标本馆。     

Effect of cyantraniliprole on feeding behavior and virus transmission of Frankliniella fusca and Frankliniella occidentalis (Thysanoptera: Thripidae) on Capsicum annuum

The anthranilic diamide insecticide cyantraniliprole was previously shown to reduce transmission of Tomato spotted wilt virus (TSWV) to pepper, Capsicum annuum, by Frankliniella fusca but not Frankliniella occidentalis. This study examines the effects of cyantraniliprole and imidacloprid on thrips feeding using electrical penetration graphing (EPG), and on TSWV transmission in field cage studies. Some antifeedant responses were observed in the EPG studies when thrips fed on cyantraniliprole- and imidacloprid-treated plants; however, these responses were variable between species and among the 2, 6, and 10 day post-treatment time intervals during which feeding behavior was observed. Cyantraniliprole significantly reduced the probability of TSWV infection when spread by F. fusca in field-grown pepper when viruliferous thrips were released 7 days but not when released at 14 days after the insecticide treatment in one of 2 field trials. In the second trial cyantraniliprole significantly reduced the probability of infection when F. fusca were released 14 days but not 7 days after treatment. In both years, imidacloprid prevented or significantly reduced transmission of TSWV by F. fusca in field-grown pepper when viruliferous thrips were released 7 days and 14 after treatment. In one of two years, cyantraniliprole significantly reduced the incidence of TSWV in field-grown pepper that was spread by F. occidentalis when viruliferous thrips were released 7 days after the insecticide treatment, but not 14 days after the treatment. Imidacloprid did not reduce the incidence of TSWV in field-grown pepper when viruliferous F. occidentalis were released. Although these studies demonstrate that probing behavior of these thrips species is altered on cyantraniliprole-treated pepper plants, results of field cage studies did not consistently show a reduction in incidence of TSWV-infected plants.     

豆大蓟马的生物学特性研究

豆大蓟马[Megalurothrips usitatus(Bagnall)]是海南豇豆的重要害虫,是影响豇豆质量安全的主要因素。通过室内试验,对豆大蓟马的发育速率、有效积温、产卵量和成虫寿命等生物学特性进行研究。结果表明:在15~35℃温度范围内,豆大蓟马的世代发育历期为10.57~46.29 d,其中卵期为2.72~8.71 d,若虫期为3.54~16.24 d,预蛹期为0.76~3.62 d,蛹期为2.02~8.74 d,产卵前期为1.00~9.16 d;各虫态发育速率与温度呈二次回归关系,且呈显著相关;卵、若虫、预蛹及蛹期的发育起点温度分别为6.18、9.80、9.37、8.83℃,有效积温依次为76.55、76.77、17.06、46.73日·度,完成世代发育起点温度和有效积温分别为9.35℃和238.87日·度;温度对豆大蓟马的存活率影响显著;成虫寿命随着温度的升高而缩短,15℃下平均寿命为63.24 d,35℃下平均寿命为11.20 d;30℃时产卵量最高,平均产卵232.78粒/雌,分别是15℃和35℃下的3.84倍和8.87倍。本研究结果为进一步开展豆大蓟马的科学防控提供了基础资料。     

Variation in Bactericera cockerelli (Hemiptera: Triozidae) Oviposition,Survival, and Development on Solanum bulbocastanum Germplasm

The potato psyllid, Bactericera cockerelli, is a key pest of potato and important vector of the pathogen that causes zebra chip disease. Control of zebra chip relies entirely on the use of insecticides to reduce populations of this vector. The development of potato varieties resistant to B. cockerelli would contribute to cost-effective control of this insect. Wild potato germplasm are key sources for desirable traits including pest resistance to develop new potato cultivars. Our objective was to screen Solanum bulbocastanum germplasm for resistance to B. cockerelli. The combined use of choice and no-choice assays demonstrated considerable variability among S. bulbocastanum populations in their susceptibility to psyllids. At least six S. bulbocastanum populations exhibited resistance to B. cockerelli: PI 243512, PI 243513, PI 255518, PI 275194, PI 275197, and PI 283096. The documentation of the variability among S. bulbocastanum germplasm populations in their susceptibility to B. cockerelli can aid the development of potato cultivars that are naturally resistant to the potato psyllid.     

Temporal and spatial distribution of an invasive thrips species Scirtothrips dorsalis (Thysanoptera: Thripidae)

Dispersion of a new invasive thrips species in the United States, chilli thrips Scirtothrips dorsalis Hood, was studied on three plant hosts, i.e., cotton (Gossypium hirsutum L.), peanut (Arachis hypogeal L.) and pepper (Capsicum annum L.) in the greenhouse and under field conditions in Homestead, Florida. In the vertical distribution study, a strong negative relationship was observed between thrips density and height, with the significantly highest mean number of larvae and adults reported on host plants placed at the lowest height (45.7 cm) above ground. The study of horizontal distribution showed that S. dorsalis has weak dispersal potential and aggregates in open areas. During the entire six week study period, thrips were found to move a maximum of 12 m from their reservoir population. During two years (2009–2010 and 2010–2011) of study, a high abundance of thrips population was observed during May–October with the highest mean count during July and August in both years. Flight activity of adults was highest between 10:00and16:00 EST, during peak solar radiation (∼337–653 w/m²). Results from these studies will help growers and extension personnel predict farm-scale distribution of S. dorsalis and efficiently monitor the pest for management before they become a serious problem for the vegetable and ornamental industry in the United States.     

Temperature Effects on the Development and Reproduction of Three Trichogramma (Hymenoptera: Trichogrammatidae) Species Reared on Trichoplusia ni (Lepidoptera: Noctuidae) Eggs

The cabbage looper, Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae) is a generalist species and an important pest of Brassicaceae worldwide. Egg parasitoids are a feasible alternative for the control of this species. We evaluated the suitability of T. ni eggs as hosts for three Trichogramma Westwood (Hymenoptera: Trichogrammatidae) species and their tolerance to survive and develop within a range of temperatures between 15 and 30°C under laboratory conditions. The species evaluated were Trichogramma pretiosum Riley, Trichogramma atopovirilia Oatman and Platner, and Trichogramma acacioi Brun, Moraes and Soares. Parasitism rate was affected by temperature, parasitoid species, and by the interaction between these two factors. Parasitoids developed and reproduced in the range of temperatures evaluated, but Trichog. acacioi failed to parasitize T. ni eggs at 30°C. The highest parasitism rates of Trichog. atopovirilia and Trichog. pretiosum occurred at 20 and 25°C and Trichog. acacioi at 25°C, with parasitism rate above 70% in the three species. Parasitoid emergence was not affected by temperature or species. The estimated thermal constant and lower temperature threshold were 134.6 DD and 10.6°C for Trichog. pretiosum and 130.1 DD and 11.2°C for Trichog. atopovirilia. The results demonstrated that Trichog. pretiosum and Trichog. atopovirilia are the most suitable species for the control of T. ni, as they can remain active throughout the year in subtropical regions.     

Color preference,seasonality, spatial distribution and species composition of thrips (Thysanoptera: Thripidae) in northern highbush blueberries

We investigated color preference, seasonal abundance, spatial distribution and species composition of thrips in northern highbush blueberries, Vaccinium corymbosum L., in New Jersey (USA). White sticky traps were more attractive to thrips compared with yellow or blue traps. Thrips captures using white sticky traps showed that their flight activity begins 20–30 d after the onset of flowering, with 10, 50 and 90% of trap captures observed at 383, 647 and 1231 degree-day accumulations, respectively (10 °C base temperature). Two methods were used to study thrips distribution within a blueberry bush. First, white sticky traps were placed within the bush canopy at three different heights. The highest numbers of thrips were caught on traps in the middle and top one-third of the canopy while the lowest numbers were caught in the bottom one-third. A second method determined the distribution of thrips on the blueberry plant at different heights and phenological stages. The highest numbers of thrips were found on young leaves at lower parts of the canopy, whereas flowers and fruit had fewer thrips and none were found on buds; these thrips were identified as, Scirtothrips ruthveni (88% of adults) and Frankliniella tritici (12%). The distribution of thrips within a blueberry planting was investigated using an evenly-spaced grid of white sticky traps in combination with on bush beating-tray samples. Thrips counts from traps correlated with direct counts on the bush across the entire blueberry field (macro-scale level); however, within the field (micro-scale level), there was no correlation between the number of thrips on traps and on individual bushes near traps. Early in the season, trap counts were higher on bushes closer to the forest, indicative of movement of thrips from wild hosts into blueberry fields. However, this was not the case for direct on bush counts or trap counts for the later part of the season, where there was no clear forest “edge” effect. Percent fruit injury due to thrips feeding was low, and it correlated with thrips counts on bushes but not from counts on traps. Overall, our data show that thrips counts on sticky traps need to be interpreted with care because these numbers weakly correlated with the numbers of thrips on bushes at the micro-scale level and percent fruit injury; however, they can be useful predictors of thrips activity across entire blueberry fields (macro-scale).     

Resistance of Oryza spp. to thrips, Stenchaetothrips biformis (Bagnall) (Thysanoptera: Thripidae)

A method to evaluate rice cultivars for resistance to Stenchaetothrips biformis (Bagnall) in the greenhouse was developed. Eleven traditional cultivars of Oryza sativa and 12 wild rices were selected for resistance. Studies on the mechanisms of resistance indicated that resistant cultivars were non-preferred for feeding and oviposition. Larval survival was lower and adult life shorter on resistant compared with susceptible cultivars. Resistant cultivars had an adverse effect on fecundity and oviposition rate which resulted in a low population growth. Plant injury on susceptible cultivars reduced plant weight and height.     

寄主植物对螺旋粉虱发育和繁殖的影响

了解螺旋粉虱在海南几种重要寄主植物上的生物学习性,为其防控提供预警,同时可筛选出适宜的扩繁寄主.以香蕉、印度紫檀、榄仁树、木薯、木瓜、番石榴及辣椒等7种植物为寄主,在温度16～29℃、相对湿度65 ％～91％的隔离大棚中观察螺旋粉虱的发育、存活、繁殖和虫体大小等情况.结果表明:螺旋粉虱由卵至成虫的发育时间以在木薯上最短,为41.33 d;其次为番石榴及辣椒,分别为42.28、42.44 d;香蕉上的发育历期最长,为56.31 d.卵至成虫存活率以在辣椒上最高,为20.00％;木薯上最低,为3.64％.平均产卵量以在辣椒上最多,为117.63粒;香蕉上最少,为73.44粒.种群趋势指数在辣椒上最大,为12.323 1;木薯上最小为1.710 3.综合比较可知,辣椒是螺旋粉虱种群生长发育和繁殖最适宜的寄主,其次为番石榴.     

Evaluation of two non-destructive sampling methods for bean thrips (Thysanoptera: Thripidae) detection in navel oranges

Adult bean thrips, Caliothrips fasciatus (Pergande), over-wintering inside the navel of navel oranges in California are an export problem when detected in fruit sent to Australia. At present, a systems approach is used to reduce fruit infestation levels and one component of this approach is to search for thrips inside the navel by cutting 50 fruit per block prior to harvest and 75 fruit per grower lot before packing in the packinghouse with any detection of live bean thrips leading to that grower lot not being eligible for shipment to Australia. Given that bean thrips infestation levels are often 0.5% of the fruit or less, this amount of fruit cutting can lead to shipment of infested lots of citrus to Australia. As an alternative to cutting more fruit, two non-destructive methods of sampling for bean thrips inside the navel of navel oranges were investigated which might be used on larger numbers of fruit and result in fewer infested lots being shipped to Australia. A light trap at the apex of a pyramid-shaped black cloth tent caught 41.1% of adult bean thrips released at the bottom of the tent. When this experiment was repeated with the tent placed over a citrus bin two-thirds full of fruit, however, only 9.3% of thrips released at the bottom of the bin were captured. A second method of sampling, washing bean thrips out of the navel onto a screen, resulted in close to 90% recovery of thrips with each of the five spray rinses evaluated, including distilled water. Regression analysis indicated there was no statistical difference between results with the five rinses. Thus, it might be worthwhile trying to scale-up our laboratory method of rinsing with distilled water to a method that might be used in a commercial packinghouse for detection of bean thrips in large numbers of fruit. Even if one assumes that cutting fruit is 100% efficient in finding bean thrips inside the navel of navel oranges, sampling a much larger number of fruit using a method with 90% efficiency is shown to result in higher odds of finding any bean thrips that are present.     

Optimum density of chrysanthemum flower model traps to reduce infestations of Frankliniella intonsa (Thysanoptera: Thripidae) on greenhouse strawberry

In a previous study, we showed that a chrysanthemum flower model trap, developed by modifying an artificial yellow chrysanthemum flower, was more attractive to the flower thrips Frankliniella intonsa Trybom (Thysanoptera: Thripidae) than a commercial yellow sticky trap. In this study, the optimum deployment density of the chrysanthemum flower model trap for reducing thrips infestation was investigated in commercial strawberry greenhouses. The traps were installed within the plant canopy at different densities (0, 5, 10, 20 traps per 50 m² plot) in three greenhouses using a randomized complete block design. The highest density of traps reduced seasonal populations of F. intonsa on strawberry flowers by 82% compared to the untreated control. The traps caught approximately 4.6 times more female than male F. intonsa, though the numbers of females and males in the flowers were similar and were both equally reduced with increasing trap density. A weak correlation (r = 0.54) was found between the number of female F. intonsa trapped and numbers in strawberry flowers, but there was no correlation (r = −0.03) for males. The results indicate flower model trap can be an additional tool for monitoring and/or management tactics against this anthophilous thrips.     

Morphological and DNA Barcoding Evidence for Invasive Pest Thrips,Thrips parvispinus (Thripidae: Thysanoptera), Newly Recorded From India

South East Asia pest thrips species, Thrips parvispinus (Karny), is a serious pest on a number of agricultural and horticultural crops in a number of plant families. Based on an integrated approach of morphology and DNA barcoding, invasion of this serious pest is reported first time from India on papaya plantations. Molecular data have corroborated with the morphological identification. Haplotyping data suggested that the Indonesia may be a probable source of invasion of this pest to India.     

Effect of cowpea/maize mixed cropping on the incident light at the cowpea canopy and flower thrips (Thysanoptera: Thripidae) population density

The effect of mixed cropping of cowpeas with maize on light intensity in the cowpea canopy and on population density of Megalurothrips sjostedti (Trybom) was investigated in the field and in cages. Significantly less (P< 0 · 05) light was intercepted by the cowpea canopy in the cowpea/maize mixed crop than in the cowpea crop alone. The population density and activity of M. sjostedti were significantly less in the mixed crop than in the single crop. There were significant correlations between light interception and differences in the population density of nymphs (r=0 · 79), adults (r=0 · 84) and the overall activity (r=0 · 93) of M. sjostedti. In a screenhouse choice test, M. sjostedti preferred unshaded cowpea plants to shaded ones. The results suggested that reduced light intensity in the cowpea/maize mixture contributes to the relative scarcity of M. sjostedti in the mixture.     

Field evaluation of selected botanicals and commercial synthetic insecticides against Thrips tabaci Lindeman (Thysanoptera: Thripidae) populations and predators in onion field plots

The effectiveness of three botanical insecticides (neem, datura and bitter apple), and three new chemistry synthetic insecticides (acephate, spirotetramat and spinetoram) against onion thrips (Thrips tabaci) was evaluated in experimental field plots at university of Sargodha, Pakistan. The influence of these botanical and chemical insecticides on natural predators and crop yield was simultaneously investigated. All the botanicals and chemical insecticides tested caused significant reductions (45–70%) in thrips populations; the botanicals gave more than 60% control of thrips, while among chemical insecticides, acephate was found to be the most effective followed by spirotetramat and spinetoram, respectively, and these insecticides gave better control than the botanicals. The adverse effects of the botanicals on predator populations were negligible compared to the chemical insecticides. All chemical treatments resulted in a significantly higher yield compared to the untreated control. The botanicals and chemical insecticides became less effective by 7 days after treatment. Therefore, it is recommended that treatment with botanical or chemical insecticides should be repeated weekly consecutively at least three times to keep thrips populations below economic injury levels until crop maturity.     

Biological response of chilli thrips, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae), to various regimes of chemical and biorational insecticides

The chilli thrips Scirtothrips dorsalis (Hood) (Thysanoptera: Thripidae), a new invasive pest in the USA, is an economically important pest of certain vegetable, ornamental and fruit crops in southern and eastern Asia, Oceania and parts of Africa. These crops cannot be protected from the pest without resorting to the use of chemical insecticides. In order to forestall or delay the development of insecticide resistance in S. dorsalis, we continued our focus on the discovery of insecticides with different modes of action for rotational use. In this study we evaluated candidate insecticides to control S. dorsalis on ‘Jalapeno’ pepper, Capsicum annuum L.; these materials belong to different IRAC mode of action classes as follows: (i) 4A – neonicotinoids, i.e., imidacloprid, thiamethoxam and dinotefuran, (ii) 5 – spinosyns, i.e., spinosad and spinetoram, (iii) 3A – pyrethroids, i.e., β-cyfluthrin, esfenvalerate, ζ-cypermethrin and λ-cyhalothrin and (iv) 8D – borax mixed together with orange oil and detergents in the TriCon^® formulation. In addition we evaluated the entomopathogenic fungus, Beauveria bassiana (Botanigard^®) alone and in combination with the borax formulation at ½ of their usual rates of application. Each of the 3 neonicotinoid insecticides when applied either as a single foliar spray or as a soil drench significantly suppressed both adults and larvae for at least 10 days; indeed imidacloprid did so for 15 days. Dinotefuran was more effective as a foliar spray than as a soil drench. Spinosyns applied as a single foliar spray, significantly suppressed both adults and larvae through 15 days after treatment (DAT). None of the 4 pyrethroids provided significant suppression of either adults or larvae. The borax formulation suppressed adults and larvae through 10 DAT. B. bassiana significantly suppressed only the larvae at 5 DAT and not at 10 DAT. This study brings the number of insecticides known to be effective against S. dorsalis to 10 and these belong to 7 different modes of action classes. The use of such insecticides in rotation belonging to different classes will help delay the development of insecticide resistance in S. dorsalis.     

温度对芒果小爪螨实验种群增长的影响

在16,20,24,28,32℃条件下观察芒果小爪螨的发育、存活及繁殖情况。结果表明:芒果小爪螨世代发育历期在32℃时最短,为9.20d,16℃时最长,为29.07d。卵、幼螨、若螨、产卵前期及世代的发育起点温度分别为8.77,9.37,10.61,11.13,8.91℃,有效积温分别为93.46,30.29,44.96,14.24,191.83日度,在16～32℃,芒果小爪螨发育的速率及雌螨寿命与温度呈直线相关。世代存活率在24℃时最高,为89.6%,32℃和16℃时,分别降至69.1%和55.8%。雌螨产卵量在28℃时最高,达40.14粒/雌,在32℃时最低,为8.44粒/雌。卵孵化率、幼螨、若螨及世代存活率、雌螨产卵量等随温度的上升而呈抛物线趋势。净增殖率(R0)、内禀增长率(rm)、周限增长率(λ)等种群特征参数以28℃时最高,分别为27.3342,0.3957,1.4854。平均世代历期和种群加倍时间分别以32℃和28℃时最短,分别为7.5186d,1.7517d。种群增长指数以24℃时最高,28℃时略低,分别为24.88和24.45。芒果小爪螨对温度较敏感,24～28℃为芒果小爪螨种群增长的最适温度。     

寄主龄期对松粉蚧抑虱跳小蜂寄生和发育的影响

通过限制选择和自由选择试验,研究松粉蚧抑虱跳小蜂(Acerophagus coccois Smith)在扶桑绵粉蚧(Phenacoccus solenopsis Tinsley)的1~3龄若虫与雌成虫体上的寄生及其子代生长发育情况。结果表明:在限制选择和自由选择的2种试验中,松粉蚧抑虱跳小蜂均可寄生扶桑绵粉蚧的1~3龄若虫和雌成虫,其中对2龄若虫的寄生率最高,分别是41.20%和45.00%;对粉蚧雌成虫的寄生率最低,但每头僵蚧平均羽化出蜂数最多,分别为9.42头和7.00头,子代雌蜂比例也最大;子代雌蜂在粉蚧1龄若虫体内发育的历期最长,为14.62 d;在粉蚧雌成虫上发育的历期最短,为13.97 d;在粉蚧1龄若虫体内发育的子代蜂的个体最小,在粉蚧雌成虫上发育的子代蜂个体最大。因此,利用松粉蚧抑虱跳小蜂防治扶桑绵粉蚧,应以粉蚧2龄若虫为防治对象,以粉蚧雌成虫为繁殖寄主。     

起始供食时间对稻水象甲冬后成虫繁殖、取食和存活的影响

室内研究了稻水象甲冬后虫在春季获得寄主水稻前所经历的时间长短对其产卵、取食和存活的影响。供试虫（4月下旬采集）先用禾本科草坪草高羊茅饲养0、10、20、30和45 d（即供食水稻前时间）,然后用20~35 d龄的稻苗饲养,观察产卵等情况。结果表明,水稻供食前时间达到10 d后即可致使冬后虫产卵历期明显缩短,卵量下降,取食斑的数量和长度减少。当水稻供食前时间延长至20 d后,成虫在水稻上的存活历期开始明显下降。处理时间越长,对其后成虫在水稻上的生殖、取食和存活的影响越大。还讨论了春季早稻栽种时间对该虫一代发生的影响。