Colonization and predation of thrips (Thysanoptera: Thripidae) by Orius spp. (Heteroptera: Anthocoridae) in sweet pepper greenhouses in Northwest Italy

Frankliniella occidentalis (Pergande) and Thrips tabaci Lindeman (Thysanoptera: Thripidae) are major pests of sweet pepper for direct damage and tospovirus transmission. To control their infestations, Orius laevigatus (Fieber) (Heteroptera: Anthocoridae) is produced by many commercial insectaries and widely used on IPM vegetable crops of Europe. This predator is naturally widespread along the Mediterranean and Atlantic coasts, and not in more continental areas, where other Orius spp. are more common. Research was conducted in a continental area of Northwest Italy in 2002–2003 to assess the natural presence of anthocorids on pepper, and to compare their colonization and predatory ability with those of the species artificially introduced. Experiments were conducted in 12 sweet pepper greenhouses, in six of which O. laevigatus release was made. From late May to early October, thrips and anthocorids were sampled on pepper by collecting flowers; Orius spp. were also collected on neighboring wild flora. Independently of the releases, Orius specimens were found in all surveyed greenhouses, but O. niger Wolff, also captured on various wild plants, was the most abundant species. It naturally colonized crops from late June and proved to be the most efficient predator on sweet pepper in the surveyed area, if not disturbed by pesticide application. Contrarily, O. laevigatus was rarely found and only in the greenhouses in which it had been released. However its introduction resulted in thrips control before natural colonization by the native species occurred.     

东亚小花蝽人工饲料微胶囊剂型的研制及饲养效果评价

通过正交试验对东亚小花蝽Orius sauteri人工饲料微胶囊进行了配方优化研究, 明确了海藻酸钠及壳聚糖的填充比例和芯壁比例在微胶囊产率、包埋率和含水率等方面的影响。各配方因素对产率的影响程度依次为: 芯壁比 > 海藻酸钠填充比 > 壳聚糖填充比; 而各因素对包埋率的影响程度依次为: 壳聚糖填充比 > 海藻酸钠填充比 > 芯壁比; 含水率受海藻酸钠填充比影响最大, 而后依次为壳聚糖填充比和芯壁比; 在海藻酸钠填充比为2.0%、壳聚糖填充比为0.6%及芯壁比为1∶3时, 所得人工饲料微胶囊感官评定得分最高。以包埋率作为基准考量下, 取最佳配比为海藻酸钠填充比为1.0%, 壳聚糖填充比为0.8%, 芯壁比为1∶1的配方, 制作人工饲料微胶囊饲喂东亚小花蝽, 与取食朱砂叶螨Tetranychus cinnabarinus组为对照, 进行了饲喂效果试验。结果表明: 与对照组相比, 取食人工饲料微胶囊后, 东亚小花蝽1、 2龄若虫发育历期显著延长, 雌成虫寿命显著缩短; 羽化率和产卵前期差异不显著, 但产卵期、产卵量和卵孵化率显著降低。此外, 取食人工饲料微胶囊的东亚小花蝽成虫呼吸墒显著低于对照, 运动速率则显著高于对照。     

阿维菌素对南方小花蝽抑制烟蚜的影响

在室内分别测定了阿维菌素类杀虫剂1% 9512-1乳油和虫螨克对南方小花蝽Orius similis的毒力,研究了无阿维菌素介入后南方小花蝽对烟蚜Myzus persicae捕食效应所受的影响,结果表明：阿维菌素类杀虫剂对南方小花蝽具有一定毒力,不同虫态对阿维菌素的敏感性有差异,卵的敏感性明显低于若虫和成虫;不同的阿维菌素类药剂对南方小花蝽的毒力存在差异,9512-1对南方小花蝽卵、若虫及成虫的LC_５０依次为11.2743±3.8613、2.6584±1.2139、2.4508±1.3266 mg·L^-１,虫螨克则为10.8699±3.7653、6.4422±2.8596、6.4738±3.0124 mg·L^-１;阿维菌素显著降低了南方小花蝽对烟蚜的捕食量和捕食能力,也降低了同种个体间的竞争能力;阿维菌素对南方小花蝽若虫的发育速率有显著的抑制作用,但对发育速率与取食量的线性关系无明显影响,而且对存活个体成虫期的产卵量无显著影响。     

南方小花蝽液体人工饲料的饲养效果评价

为评价一种液体人工饲料的饲养效果,以棉蚜饲养南方小花蝽作对照,用液体人工饲料连续两代饲养南方小花蝽若虫和成虫,对南方小花蝽各生长阶段的生长和发育指标进行调查。结果显示：用人工饲料饲养的南方小花蝽若虫历期（22～23天）与对照组（21天）之间不存在显著差异,说明液体人工饲料可以很好的满足南方小花蝽若虫生长的营养要求。然而,用棉蚜饲养的对照组南方小花蝽成虫获得率可达到63%,而人工饲料组连续两代的成虫获得率分别仅为45% 和43%。取食人工饲料的南方小花蝽成虫,在产卵前期、产卵量及寿命方面与对照组都没有显著差异,仅在产卵期方面有着显著差异,人工饲料组小花蝽的产卵期为13～16天,而对照组小花蝽的产卵期可达20天,说明液体人工饲料也可以很好的满足南方小花蝽成虫生殖发育的营养要求。     

Attraction of a generalist predator towards herbivore-infested plants

The occurrence and strength of interactions among natural enemies and herbivores depend on their foraging decisions, and several of these decisions are based on odours. To investigate interactions among arthropods in a greenhouse cropping system, we studied the behavioural response of the predatory bug Orius laevigatus (Fieber) (Hemiptera: Anthocoridae) towards cucumber plants infested either with thrips (Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae)) or with spider mites (Tetranychus urticae Koch (Acari: Tetranychidae)). In greenhouse release-recapture experiments, the predatory bug showed a significant preference for both thrips-infested plants and spider mite-infested plants over clean plants. Predatory bugs preferred plants infested with spider mites to plants with thrips. Experience with spider mites on cucumber leaves prior to their release in the greenhouse had no effect on the preference of the predatory bugs. However, this experience did increase the percentage of predators recaptured. Y-tube olfactometer experiments showed that O. laevigatus was more attracted to odours from plants infested with spider mites than to odours from clean plants. Thus, O. laevigatus is able to perceive odours and may use them to find plants with prey in more natural conditions. The consequences of the searching behaviour for pest control are discussed.     

Feeding and ovipositing on plants by an omnivorous insect predator

Omnivory (i.e., feeding at more than one trophic level) is common in many ecological communities. To date, most studies of omnivory have focused on systems that include omnivores that feed on several prey items, primarily in aquatic systems. Yet, many terrestrial insect predators feed not only on prey but also on plants. The difference between systems with plant-feeding omnivores and those with exclusively prey-feeding omnivores calls for special attention. The first step towards understanding the interactions between plant-feeding omnivores and their prey is to determine how omnivores respond to variations in plant properties. In this study, I investigated two major aspects of the interactions between the plant-feeding predatory bug Orius insidiosus and four host plants of its prey; the behavioral aspect, in which plants are selected for oviposition and the physiological aspect, in which plants differ in their suitability for the insect's growth, survival, and reproduction. No prey was offered to the omnivore during any of the experiments, but older nymphs and adults were fed prey eggs prior to their use in the experiments. Data show that O. insidiosus females almost completely rejected corn leaves for oviposition; nymph and adult survival was highest on bean; and female fecundity was higher on bean than tomato, pepper or corn foliage. the significance of the apparent ability of O. insidiosus to discriminate among plants and the observed correlation between oviposition preference and offspring performance in bean and in corn is discussed.     

Potential of adultOrius insidiosus [Hemiptera: Anthocoridae] as a predator of the fall armyworm,Spodoptera frugiperda [Lepidoptera: Noctuidae]

Orius insidiosus (Say) was observed to successfully prey on eggs and earlier instar larvae of the fall armyworm (FAW),Spodoptera frugiperda (J. E. Smith). Significantly more neonates of FAW were killed per 24 h than either 1, 2 or 3 d old larvae. Female and male predators exhibited a typical type-II functional response when preying on varying densities of eggs or neonates of FAW.      

Rearing of Orius strigicollis (Heteroptera: Anthocoridae) on Artificial Diet

Orius strigicollis (Poppius) was reared on the modification of rearing media for Tetrastichus sp. at 28°C, 18L: 6D, and 50‐60% RH, in which meat diets were used for partial replacements of insect source of the artificial diets. Life history traits of the predacious bug fed on the diet were measured. Nymphal development period and mortality rate of O. strigicollis were about 14 days and 31.5% (survival rate: 68.5%), respectively. The female bug produced average of 82.5 eggs during its oviposition period of 18 days when artificial oviposition substrate was provided. The fecundity was shown to be superior compared with previous researches on the species fed natural preys as a food.     

Overwintering Biology of the Predatory Bug Orius albidipennis (Hemiptera: Anthocoridae) in Israel

The predatory bug Orius albidipennis (Hemiptera: Anthocoridae) overwinters in Israel as adults. Oviposition continues irrespective of day length, but stops almost completely when the mean temperature drops below 15 C (beginning in December). During winter months, the outdoor females enter reproductive diapause, and resume oviposition in during March and April. All first instar nymphs die at low temperatures, whereas approximately 20% of the nymphs of later instars may survive and mature. Dense populations of the western flower thrips, Frankliniella occidentalis, develop outdoors in Israel about a month before the peak in population of O. albidipennis, and have the opportunity to cause much damage. Since the Israeli O. albidipennis does not enter diapause under short day photophase, it might be an efficient predator of F. occidentalis in greenhouses in countries of northern latitude.     

A one‐step,single tube,duplex PCR to detect predation by native predators on invasive Bemisia tabaci MEAM1 and Frankliniella occidentalis

Bemisia tabaci (Gennadius) MEAM1 (Hemiptera: Aleyrodidae) and Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), two important invasive species, are serious agricultural pests. In this study, a one‐step, single tube, duplex polymerase chain reaction (PCR) procedure was developed to allow rapid, specific, and sensitive identification of B. tabaci MEAM1 and F. occidentalis in predator guts. The system and conditions used for the duplex PCR were optimized. The species specificity of the duplex PCR determined by comparison against non‐targets that might interact with B. tabaci MEAM1 and F. occidentalis showed that oligonucleotide primers amplified nuclear gene target sequences present only in B. tabaci MEAM1 or F. occidentalis. The limits of detection were 9.53 ng μl^?1 for B. tabaci MEAM1 and 8.94 ng μl^?1 for F. occidentalis. Within a field cage study, in which predators Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) and Orius sauteri (Poppius) (Hemiptera: Anthocoridae) were allowed to feed on B. tabaci MEAM1 and F. occidentalis for 10 h, the B. tabaci MEAM1 DNA was detectable in 100% of H. axyridis and O. sauteri, and F. occidentalis DNA was detectable in 80% of H. axyridis and 90% of O. sauteri; this implicated that B. tabaci MEAM1 and F. occidentalis remains could be detected in native predator guts simultaneously. The accuracy and reliability of the assay suggested strongly that the duplex PCR optimized for B. tabaci MEAM1 and F. occidentalis is sensitive and specific for both invasive insects and is therefore useful in early diagnosis and monitoring of B. tabaci MEAM1 and F. occidentalis infections, and can be used to identify domestic predator species and food web relationships.