烟粉虱对寄主植物的选择

烟粉虱[Bemisia tabaci(Gennadius)]是小黑瓢虫[Delphastus catalinae(Horn)]的捕食猎物之一。提供6种寄主植物进行烟粉虱的选择试验,发现寄主植物对烟粉虱生长发育和存活的影响不明显,主要影响其成虫生殖力和种群增长。通过比较烟粉虱的种群增长指数(I),发现花椰菜、一品红、豇豆和烟草这4种寄主植物比较适合用于人工大量繁育烟粉虱,其中花椰菜的饲养效果最佳,最有利于烟粉虱种群的快速增长。     

Bioassay evaluation of the entomopathogenic fungi, Beauveria bassaina Vuellemin against eggs and nymphs of Bemisia tabaci Gennadius (Homoptera: Aleyrodidae)

This study was carried out to determine the lethal effect of the entomopathogenic fungi, Beauveria bassaina Vuell. on eggs, young and old nymphs of the whitefly, Bemisia tabaci Genn. Mortality percentage was significantly differed based on stage of B. tabaci and conidial concentrations of B. bassina. Average of the infection level to insect was very low particularly in eggs with only 4.49%, even with higher conidial concentrations (6 x 10(6) conidia mL(-1)). Whereas, it was higher with 1st and 2nd instars (42.045%) and 3rd and 4th instars (35.93%). Three parameters was assessed with B. tabaci eggs, namely; egg infection, egg hatchability and crawlers emergence. Egg mortality percentages averaged 1.2, 4.27 and 8.0% with fungal concentration 2 x 10(6), 4 x 10(6) and 6 x 10(6) conidia mL(-1), respectively. Daily infection percentages were varied depend upon the conidial concentration where the highest infection rate of eggs was occurred with 6 x 10(6), followed by 4 x 10(6) conidia mL(-1). Egg hatch was very high, while the mortality among the emerged crawlers was neglectable compared with the check. Efficiency of B. bassaina on whitefly nymphs also was varied based on the insect instar and fungal concentration. Mortality percentages were obviously higher to young nymphs (1st and 2nd instars) than to older ones (3rd and 4th instars). The results indicated that nymphs were highly susceptible to fungal treatment compared with eggs. Additionally, pathogenicity and virulence of B. bassaina against B. tabaci immatures was not indicated by LC50 only, but also, by the time in days (LT50) required to achieve 50% mortality of an insect.     

中国烟粉虱寄生蜂资源及其区系分布

对中国寄生烟粉虱的寄生蜂种类、寄主类别和分布地区进行了系统论述。根据采集调查和文献记录,目前中国烟粉虱寄生蜂约有27种,占世界记录总数的54%,主要隶属膜翅目(Hymenoptera)蚜小蜂科(Aphelin-idae),其中,恩蚜小蜂属(Encarsia)的21种,桨角蚜小蜂属(Eretmocerus)的6种。主要分布于长江流域以南的福建、广东、广西、台湾和香港等地,台湾种类分布最多。同时,对中国烟粉虱寄生蜂的地理区系分布进行了分析和讨论。     

桑小头木虱Paurocephala sauteri Enderlein生物学特性研究

近年在海南各植桑区均发现桑小头木虱（Paurocephala sauteri Enderlein）严重为害,桑园被害株率达100%。在我国,该木虱仅记录于台湾省,为我国大陆新入侵害虫。本研究在实验室条件下[(27±1)℃、RH (70±5)%、12L∶12D],采用45日龄桑树扦插苗和离体叶片饲养,对桑小头木虱的发育与繁殖特性及各虫态的形态特征开展观察。结果表明,桑小头木虱生活史包括卵、1~5龄若虫和成虫期。各龄期主要形态特征为：卵呈水滴形,带短的卵柄,端部具细长的端丝,初产时乳白色,待孵化时可见淡红色眼点;1龄若虫头、胸部乳白色,复眼和腹部橘黄色,无翅芽;2~5龄若虫黄绿色,随着龄期增加,体长增加,翅芽随之变化。2龄翅芽出现,稍突起;3龄翅芽较小,呈三角形;4龄和5龄翅芽长椭圆形,其中5龄超过腹部第1节。各龄若虫和初羽化成虫均可分泌白色球形蜡质。雌雄成虫以两性生殖方式繁殖后代,羽化3 d后体色由黄绿色逐渐变为黄褐色并开始交配,交配时间为0.5~3 h,结束交配18~21 h后开始产卵,产卵量为20~42粒。卵单个散产于叶片背面叶脉处,偶尔可见产于新抽嫩叶正面边缘,5~7 d后孵化,孵化率为98.19%,雌性百分率为70.44%。若虫期12~18 d,完成一代的时间为18~24 d。本研究将为桑小头木虱的准确识别与监测,以及防控策略的制定提供前提条件和理论依据。     

黑肩绿盲蝽在寄主植物、飞虱和叶蝉卵上的生长和发育

 系统地测定了不同寄主卵和寄主植物对稻飞虱重要天敌黑肩绿盲蝽Cyrtorhinus lividipennis Reuter生长和发育的影响。结果表明，在实验室条件下黑肩绿盲蝽能在水稻以及禾本科杂草如稗草Echinochloa glabrescens、千金子Leptochloa chinensis、马唐Digitaria ciliaris和狗牙根Cynodon dactylon上生长和繁殖。大田连续采样证实该盲蝽在稻田周围杂草地只能作短暂停留。黑肩绿盲蝽的若虫龄数随寄主卵和寄主植物的变化而变化，表现为5龄、6龄和4龄。水稻和禾本科花穗与飞虱蜜露或蜂蜜的结合可为黑肩绿盲蝽的生长和发育提供重要的营养源。该研究将为黑肩绿盲蝽的自然保护利用提供重要的理论依据。     

黑肩绿盲蝽在寄生植物、飞虱和叶蝉卵上的生长和发育

系统地测定了不同寄主卵和寄主植物对稻飞虱重要天敌黑肩绿盲蝽ＣｙｒｔｏｒｈｉｎｕｓｌｉｖｉｄｉｐｅｎｎｉｓＲｅｕｔｅｒ生长和发育的影响。结果表明，在实验室条件下黑肩绿盲蝽能在水稻以及禾本科杂草如稗草Ｅｃｈｉｎｏｃｈｌｏａｇｌａｂｒｅｓｃｅｎｓ、千金子Ｌｅｐｔｏｃｈｌｏａｃｈｉｎｅｎｓｉｓ、马唐Ｄｉｇｉｔａｒｉａｃｉｌｉａｒｉｓ和狗牙根Ｃｙｎｏｄｏｎｄａｃｔｙｌｏｎ上生长和繁殖。大田连续采样证实该盲蝽在稻田周围杂草地只能作短暂停留。黑肩绿盲蝽的若虫龄数随寄主卵和寄主植物的变化而变化，表现为５龄、６龄和４龄。水稻和禾本科花穗与飞虱蜜露或蜂蜜的结合可为黑肩绿盲蝽的生长和发育提供重要的营养源。该研究将为黑肩绿盲蝽的自然保护利用提供重要的理论依据。     

Parasitism,Emergence, and Development of Spalangia endius (Hymenoptera: Pteromalidae) in Pupae of Different Ages of Bactrocera cucurbitae (Diptera: Tephritidae)

The wasp Spalangia endius Walker (Hymenoptera: Pteromalidae) is a major parasitoid of the pupae of fruit flies, which are a common agricultural pest. An understanding of this intricate host–parasitoid interaction could provide basic information necessary for the sustainable integrated biological control of fruit flies. In this study, we investigated the effect of S. endius on different-aged pupae of the melon fly Bactrocera cucurbitae Coquillett by using choice and nonchoice tests under laboratory conditions. We showed that S. endius females oviposited, and their progeny successfully developed, in different-aged pupae of B. cucurbitae regardless of the method of exposure. There was an oviposition preference for 3–5-d-old pupa. The highest mean percentage parasitism occurred on 4- and 5-d-old hosts, followed by 2- and 3-d-old hosts. The average development time for both males and females was significantly longer in 6–7-d-old hosts than in the younger host stages. Adult females that developed from younger host pupae (2–5-d old) were significantly heavier than those from older host pupae (6–7-d old), and they also lived longer. The sex ratio (proportion of females) of the parasite progeny decreased with an increase in host age. Host mortality also decreased gradually as the pupal age increased. The differences in development time, body weight, and longevity between females and males were significant. These results suggest that S. endius is a good candidate for the biological control of B. cucurbitae.     

Density and spatial distribution of different development stages of Sternechus subsignatus Boheman (Coleoptera: Curculionidae) in soybean crops

The population recruitment and the spatial distribution of eggs, larvae, overwintering stages and adults of the soybean stalk weevil, Sternechus subsignatus Boheman, on soybean were estimated in two commercial farms of the Tucumán province, Argentina, during three consecutive productive cycles. At weekly intervals 30 sampling units were taken in a random distribution from each farm, and the number of adults as well as the number of “rings” and gall-like structures around stems and/or branches recorded, from which the number of eggs and larvae, respectively, were inferred. At fortnightly intervals 20 sampling units of soil were taken at random and the number of overwintering stages recorded. The recruited number of the different developmental stages was analyzed by nested ANOVA, and the spatial distribution was estimated by the Taylor's Power law and Iwao's regression methods. Adults were recorded in all samples while eggs and larvae were found from mid-January to late April. The recruited number of the different stages was low and did not differ between stages or farms, and the spatial disposition of all developmental stages was at random. This study constitutes the first of its kind for this pest, and provides information that will be useful for the purposes of monitoring for biological studies and for insect pest control in the field.     

Potato minituber production using aeroponics: Effect of plant density and harvesting intervals

To optimize minituber production through aeroponics some horticultural management factors should be studied. Potato plantlets, cv Zorba, were grown aeroponically at two different plant densities (60 and 100 plants/m²). Plants showed an extended vegetative cycle of about 5 months after planting. A higher number of stolons was obtained at low plant densities. Tuber formation hastened when supplied N was reduced. Experiments on harvesting intervals (7, 10, and 14 days) indicated that for a density of 60 plants/m², both number of minitubers and yield increased as harvesting interval decreased. Best results were achieved harvesting every 7 days: a total tuber yield of 118.6 g per plant was obtained (four times higher than for 100 plants/m²). Such a yield was composed, on the average, of 13.4 tubers with a mean tuber weight of 8.1 g. Harvesting intervals did not have an effect on the number of minitubers and yield for a density of 100 plants/m². The best productivity obtained in this study was 800 minitubers/m² for weekly harvests and a low plant density (60 plants/m²). We also studied the field performance of aeroponically produced minitubers vs those produced by hydroponics. Minituber behavior under field conditions was independent from the technique used for its production.     

Cuban brown snail,Zachrysia provisoria (Gastropoda): Damage potential and control

The snail Zachrysia provisoria (Pfeiffer) is poorly known in Florida, USA, where it predominately is viewed as a pest of ornamental plants. I evaluated its host plant relationships, foliage consumption potential, and susceptibility to several molluscicides. Many of the potential hosts, especially common ornamental plants that are planted densely as ground cover and might be expected to provide a favorable environment for snails, are not suitable for growth of young snails. Older snails, though displaying some ability to feed and damage hosts unsuitable for growth of young snails, displayed similar patterns of acceptance and growth. Several weeds were favorable for growth, suggesting that untended environments could lead to snail problems in adjacent ornamental plantings. The effect of plant condition (age) on snail feeding preference was assessed by measuring leaf consumption by snails presented simultaneously with young (green, located apically) and senescent (yellowing or yellow, located basally) leaves of a single plant species. From preferred host plants, snails chose young leaf tissue, but from less preferred plants they consumed senescent tissue. Foliage consumption potential was assessed using romaine lettuce at two constant temperatures, 24 and 32 °C. Foliage consumption increased with age (wet weight) at both 24 and 32 °C; however, the rate of consumption was higher at the lower temperature. At 24 °C, mean peak consumption was about 40 cm² of leaf area or 12 g wet weight/day. At the less favorable high temperature of 32 °C, mean peak consumption was reduced by about 50%, to a mean of only 20 cm² or 6 g wet weight/day. Relative consumption rate (cm² or g foliage/g snail) diminished with age (wet weight) of the snails. Several molluscicide-containing baits were assessed. Metaldehyde-based baits induced mortality most quickly, followed by iron-based baits. A boric acid-based bait was slowest, requiring 12 days for the induction of significant levels of mortality. All baits significantly suppressed feeding, however, sometimes even in the absence of mortality.     

Effect of different host plants on the fitness of diamond-back moth, Plutella xylostella (Lepidoptera: Plutellidae)

The diamond-back moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae) is a destructive cosmopolitan pest of cruciferous crops. The pest is present wherever its host plants exist and is considered to be one of the most widely distributed of all the Lepidoptera. We investigated the effect of various host plants on the fitness of P. xylostella and tested the hypothesis by studying development time, growth, fecundity and survival on cabbage (Brassica oleracea capitata), cauliflower (Brassica oleracea botrytis), radish (Raphanus sativus), turnip (Brassica rapa), mustard (Brassica compestris) and canola (Brassica napus var. canola). The developmental time from eggs to adult eclosion was the shortest (10 days) on canola and the longest (13 days) on turnip. Fecundity was greatest on canola (350) followed by cauliflower (268 eggs) by females eclosed from the pupae reared on canola and cauliflower, respectively, while the minimum numbers of eggs (184) were observed on cabbage. The number of eggs hatched was the highest (80%) when larvae fed on cauliflower. Survival to the adult stage was the highest (94%) on mustard followed by cauliflower and lowest (64%) on turnip. The net replacement rate was lowest for populations reared on cabbage (32.3), which was also reflected by the lowest intrinsic rate of population increase (0.20). The correlation between the intrinsic rate of population increase (r_m) and the mean relative growth rate was significant (t = 20.02 d.f. = 4, P < 0.05). Canola and mustard proved to be the most suitable hosts for P. xylostella because of shorter developmental period, higher percentage of survival and higher number of eggs. The data point to the role of host plants in increasing local P. xylostella populations.     

Effect of time between soil infestation with Pochonia chlamidosporia and planting on the efficacy of the fungus in managing Meloidogyne javanica

The fungus Pochonia chlamydosporia acts on populations of the root-knot nematode by parasitizing their eggs before they hatch, preventing the release of juveniles. In this study, the effect of the time at which the fungus is applied to soil infested with the nematode, before transplanting tomato and lettuce seedlings, was evaluated. The reduction of symptoms and the nematode population in the host plant was also evaluated, as well as the fluctuation of the fungus population during the studied period. The seedlings were transplanted at 0, 5, 10, 15 or 20 days after incorporation of the inocula of the fungus and the nematode into the soil. The population of P. chlamydosporia, without the presence of plants, increased and reached its maximum 10 days after its incorporation into the soil. At the end of the experiments, the number of colony forming units (CFU) of the fungus in the soil remained high enough to act on the next cycle of crops. For both cultures, the greatest effect on reducing the number of galls and eggs of Meloidogyne javanica was obtained by increasing the contact time of the fungus with the nematode in the soil before transplanting seedlings. In the second run, for both cultures, there was an increase in shoot weight with increasing of incubation time before the transplantation of seedlings.     

5种赤眼蜂对红脉穗螟卵的寄生力比较

红脉穗螟[Tirathaba rufivena (Walker)]是槟榔的重要害虫,为筛选有效防治红脉穗螟的优势赤眼蜂蜂种,研究比较了稻螟赤眼蜂、食胚赤眼蜂、松毛虫赤眼蜂、玉米螟赤眼蜂和螟黄赤眼蜂对红脉穗螟的寄生力。结果表明,在一定的寄主卵密度范围内,稻螟赤眼蜂、松毛虫赤眼蜂和食胚赤眼蜂对红脉穗螟卵的寄生数量随着红脉穗螟卵密度的增加而逐渐增加,其中,稻螟赤眼蜂、松毛虫赤眼蜂和食胚赤眼蜂在红脉穗螟的卵密度分别为35、30和25粒/管,寄生卵数量和寄生率均为最大,寄生卵数量分别为16.2、8.8和10.6粒,寄生率分别为46.3%、29.3%和42.4%。在赤眼蜂羽化后的12 h内,在0~72 h提供充足卵的情况下,食胚赤眼蜂、稻螟赤眼蜂和松毛虫赤眼蜂主要在0~24 h寄生红脉穗螟的卵,分别占总寄生量84.8%、48.6%和60.7%,其子代蜂总数分别为48.5、50.8和53.8头,子代雌蜂比例分别为68.2%、74.4%和55.1%。结果表明稻螟赤眼蜂对红脉穗螟卵具有较强的寄生能力,松毛虫赤眼蜂和食胚赤眼蜂作为红脉穗螟卵补充优势赤眼蜂,这3种赤眼蜂可共同防治红脉穗螟。     

Alternate crop and weed host plant oviposition preferences by the Mexican rice borer (Lepidoptera: Crambidae)

The Mexican rice borer, Eoreuma loftini (Dyar), is the key pest of sugarcane, Saccharum hybrids, in south Texas, having largely displaced the sugarcane borer, Diatraea saccharalis (F.), and it is moving into rice- and sugarcane-growing areas of east Texas and Louisiana. While a number of alternative weed and crop hosts have been reported, the extent to which they might support Mexican rice borer populations is unknown. This study involved choice assays that compared oviposition preference for and larval infestations of five mature graminaceous weed species. Levels of infestation between sugarcane and corn, Zea mays L., crop hosts and between corn and sorghum, Sorghum bicolor (L.) Moench, were also assessed. We determined that the average number of larval entry holes in sudangrass stems was ≥2.5-fold more than for any of the other four weed host plants, that corn had ≥5.9-fold more larval entry holes than sorghum and ≥8.2-fold more than sugarcane. Greater oviposition and infestation of one non-crop host over another was not related to numbers of stems per plant, but was associated with the greater stem diameter and abundance of dry leaf tissue found in Sudangrass, Sorghum bicolor (L.) Moench ssp. drummondi (Nees ex Steud.) de Wet & Harlan, johnsongrass, S. halepense (L.) and barnyardgrass, Echinochloa crus-galli (L.) P. Beauv.; relative to the other weed species in this study. In terms of the crop plants, stalk diameter and quantity of dry leaf tissue were not associated with numbers of eggs or larval entry holes in the choice assays between corn and sorghum, and between sugarcane and corn. While corn has been known as a host of the Mexican rice borer for at least 84 yr, its role in area-wide population dynamics and control efforts has likely been greatly underestimated.     

Population density and life-history parameters of the psyllid Bactericera nigricornis (Forster) on four commercial cultivars of potato

The psyllid Bactericera nigricornis (Forster) (Hemiptera: Triozidae) is one of the most important pests of potato, Solanum tuberosum L., in the Ardabil region, Iran. The use of host plant resistance is an essential component of the integrated management of B. nigricornis. In this study, we investigated the population density of B. nigricornis on four commercial cultivars of potato under field conditions and its life-history parameters under laboratory conditions. In field experiments, the lowest and highest densities of B. nigricornis were observed on cvs. Agria and Marfona, respectively. Population densities did not differ significantly between cvs. Kaiserkrone and Satina. In experiments on life-history parameters, the longest and shortest developmental times of nymphs were observed on cv. Agria (22.3 days) and cv. Marfona (18.2 days). The developmental time of nymphs on Kaiserkrone did not differ significantly from that on Satina. The lowest number of eggs laid per female (47.2) and the lowest survival rate (50%) were observed on Agria. The survival rate on Agria did not differ significantly from that on Kaiserkrone and Satina. The intrinsic rate of natural increase (r_m) and population growth rate (λ) were lowest on Agria and highest on Marfona. The generation time on Agria and Kaiserkrone was significantly longer than on Satina and Marfona. The doubling time (DT) was longest on Agria (15.9 days) and shortest on Marfona (11.8 days). Amongst the cultivars investigated, host plant resistance acted by decreasing the numbers of eggs laid per female, increasing the development time and reducing the survival rate of B. nigricornis, so decreasing population growth. Of the cultivars tested, Agria is the most resistant host and has potential for use in the integrated management of B. nigricornis on potato.     

成虫取食不同植物对越北腹露蝗卵巢发育和生殖力的影响

在越北腹露蝗（Fruhstorferiola tonkinensis Will.）成虫期间用不同的植物进行饲养,观察其卵巢发育和生殖力的变化。结果表明,取食枫杨、桑树的卵巢发育时间分别在 2004- 06- 18 至 2004- 06- 21,2004- 06-20~22,取食假蒌、白兰的卵巢发育时间在 2004- 06- 28 至 2004- 07- 01;取食上述 4 种植物的蝗虫产卵时间分别在 2004- 08- 05 至 2004- 08- 07,2004- 08- 06~08,2004- 08- 29 至 2004- 09- 02,2004- 08- 31 至 2004- 09- 02;卵巢发育历期分别为 45.75,46.50,61.25,62.25 d;每头雌蝗产下的平均卵块数分别为 1.6,1.4,0.85,0.7 块。平均卵粒数分别为 38.2,31.8,20.2,14.2 粒。说明取食枫杨和桑树有利于越北腹露蝗的卵巢发育和生殖,并且成虫营养对越北腹露蝗卵巢发育和生殖力有显著的影响。     

瓜实蝇龄期和密度对蝇蛹金小蜂寄生能力的影响

蝇蛹金小蜂是蝇类害虫重要的蛹期寄生性天敌，为了评价其对蔬菜上重要害虫瓜实蝇的控害潜能，本文就蝇蛹金小蜂对瓜实蝇蛹的寄生潜能进行了研究，建立了功能反应和干扰效应数学模型。结果表明，蝇蛹金小蜂对不同蛹龄瓜实蝇蛹的寄生功能反应均符合 HollingⅡ模型，但不同蛹龄之间的功能反应参数存在差异。蝇蛹金小蜂对 2 日龄、4 日龄和 6 日龄瓜实蝇蛹的模方程分别为 Na = 0.478 0N0/(1+0.010N0)、Na = 0.474 0N0/(1+0.008 6N0) 和 Na = 0.476 4N0/(1+0.009 9N0)。蝇蛹金小蜂自身密度也会对寄生产生一定的干扰效应，用 Hassell-Varley 模型拟合，蝇蛹金小蜂干扰效应方程可表示为：a = 0.071 9P –0.252 6。     

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。     

寄主叶片营养物质、物理结构与椰心叶甲危害的关系

在室内条件下,测定椰心叶甲对5 种主要寄主植物的选择性,分析叶片营养物质、物理结构与选择性、适合性的关系。结果表明：在自由选择与强迫选择条件下,椰心叶甲对不同种类寄主存在显著选择性,在2种情况下都最喜好取食海枣和椰子;寄主对椰心叶甲生长发育的适合性与其对寄主的偏好性并不一致,喜好取食的海枣对其生长发育非常不利,反而是不喜取食的金山葵对其生长发育最有利。对不同寄主的可溶性糖、可溶性蛋白、粗脂肪和水分进行测定的结果表明：不同寄主间营养物质与水分的含量存在极显著差异,但含量的高低与寄主对椰心叶甲适合性关系不大,只有寄主可溶性糖含量的高低与取食不同寄主后的蛹重呈正相关关系（p=0.021 2＜0.05）,但未达到极显著。对不同寄主叶片物理结构的研究表明：栅栏组织细胞宽度越大,对幼虫发育越有利,上、下表皮厚度、栅栏组织厚度与寄主选择性的关系不明显。