Insecticide toxicity and walking response of three pirate bug predators of the tomato leaf miner Tuta absoluta

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Population responses by <Emphasis Type="Italic">Orius insidiosus</Emphasis> to vegetational diversity

The abundance of different life stages of Orius insidiosus (Say) (Heteroptera: Anthocoridae) and its prey were recorded in vegetationally diverse (soybean and agronomic weeds) and monoculture (soybean only) fields. Orius insidiosus adults and nymphs were more abundant in diversified plots than in monocultures. A similar number of O. insidiosus eggs were found in the two treatments, but twice as many eggs were laid on non-crop plants than on soybeans within the vegetationally diverse plots. Prey densities were equivalent in the two treatments. In olfactometer assays, naïve O. insidiosus females were unresponsive to odors from three weed species (morning glory, redroot pigweed and velvetleaf). The current results, coupled with previous experimental observations, lead us to believe that higher abundance of O. insidiosus in vegetationally diverse habitats could be related to improved fitness of the predator, which in turn is related to certain plant qualities (e.g., nutrition, plant architecture, etc.). Proximal cues are likely more influential to oviposition decisions by O. insidiosus females than volatile signals.     

Effects of leaf nitrogen content on oviposition site selection, offspring performance, and intraspecific interactions in an omnivorous bug

Abstract.  1. Oviposition site preference and its relation to offspring performance have received much attention in studies of herbivorous insects. Although this relationship is of great ecological significance, its presence in predacious and omnivorous insects has hardly been explored. When selecting an oviposition site, omnivores are expected to respond to both prey availability and, even more strongly, to plant traits that affect both females and their offspring.
2. In this study, females of Orius albidipennis (Heteroptera: Anthocoridae) showed a strong preference for oviposition at the vein origin site of cotton leaves. It appears that this site is a limited resource for ovipositing females, because they defend it against conspecific intruders. This defensive behaviour was significantly more pronounced on nitrogen-rich than nitrogen-poor plants.
3. The females' defensive behaviour on nitrogen-rich leaves corresponds with offspring performance; the nymphs developed faster and enjoyed higher survival on nitrogen-rich than on nitrogen-poor leaves. At the between-plant level, oviposition preference was not significantly correlated with offspring performance, and egg hatching rate did not differ significantly between nitrogen treatments.
4. Oviposition site selection by this omnivorous bug appears, however, to be correlated positively with offspring performance at the within-leaf level. This is supported by the significantly higher hatching success of eggs deposited at the preferred vein origin site as compared with those deposited on other parts of the leaf.     

Predator demographics and dispersal in alfalfa trap-cropped strawberry

Alfalfa, Medicago sativa L. (Fabaceae), is a highly preferred host plant of Lygus spp. (Hemiptera: Miridae). As such, intercropping alfalfa trap-crops in strawberry production can serve as a sink for both Lygus (primarily Lygus hesperus Knight) and its natural enemies. Here we investigated the population dynamics and dispersal characteristics of the generalist predator complex in strawberry fields with alfalfa trap-crops spaced 50 rows (62 m) apart. Predator abundance was determined by counting six focal taxa collected from strawberry and alfalfa. The data revealed that Orius spp. (Hemiptera: Anthocoridae) were the numerically dominant predator taxa, comprising 84% of the focal predator population. In general, the population densities obtained for the various taxa throughout this agroecosystem were unexpectedly uniform. Predator movement from a central alfalfa trap-crop row was determined using a protein mark–capture procedure. Most protein-marked predator specimens were collected less than 2 m from the centrally marked alfalfa row, indicating that the trap-crop often produces a predator sink. Results suggest that alfalfa is a useful cultural (trap-cropping) and a biological (refuge for natural enemies) control tactic for managing Lygus spp. in strawberries.     

Foraging behavior responses of Orius insidiosus to thrips cues

The minute pirate bugs (Hemiptera: Anthocoridae) are effective biological control agents against destructive agricultural pests such as the western flower thrips, Frankliniella occidentalis Pergande (Thysanoptera: Thripidae) in agroecosystems around the world. One species, Orius insidiosus (Say), has proven effective in controlling thrips populations in fields and greenhouses, and serves as an integral component of many integrated pest management (IPM) programs. Three experiments were conducted using motion-tracking software and dual-choice Y-tube bioassays to determine whether direct thrips contact and thrips cues contact induced arrestant and attractant behaviors. The experiments revealed that O. insidiosus adults exhibited behavioral changes indicative of switching from extensive to intensive foraging after direct exposure to thrips prey. Similar arresting behavior was induced by the presence of thrips tracks alone. In Y-tube bioassays O. insidiosus showed preference towards arms containing tracks from western flower thrips larvae vs. clean arms, but only when direct contact with the tracks was made in the stem. Our data indicate that thrips deposit non-volatile semiochemicals that are used by O. insidiosus during foraging. These compounds have the potential to aid in O. insidiosus behavior manipulation which may help in early control of thrips populations in fields and greenhouses. Further research is necessary to determine the chemical composition of these cues and how to effectively and pragmatically integrate the inducing stimuli into biocontrol programs as part of IPM strategies.     

Compatibility of early natural enemy introductions in commercial pepper and tomato greenhouses with repeated pesticide applications

Successful integrated pest management in protected crops implies an evaluation of the compatibility of pesticides and natural enemies (NE), as control strategies that only rely on one tactic can fail when pest populations exceed NE activity or pests become resistant to pesticides. Nowadays in Almería (Spain), growers release NE prior to transplanting or early in the crop cycle to favor their settlement before pest arrival because this improves biocontrol efficacy, although it extends pesticide exposure periods. The purpose of this research was to evaluate the compatibility of two applications of pesticides with key NE in 2‐year trials inside tomato and sweet pepper commercial greenhouses: Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae), Orius laevigatus (Say) (Hemiptera: Anthocoridae) and Amblyseius swirskii (Athias‐Henriot) (Acari: Phytoseiidae). In tomato, flubendiamide and chlorantraniliprole (IOBC category 1) were compatible with N. tenuis, but chlorpyrifos‐methyl and spinosad (IOBC categories 2–3), which effectively reduced Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) density, compromised its predatory activity. In sweet pepper, chlorantraniliprole (IOBC category 1) was the only pesticide compatible with O. laevigatus while chlorantraniliprole, emamectin benzoate, spirotetramat and pymetrozine were harmless (IOBC category 1) to Amblyseius swirskii, and sulfoxaflor slightly harmful (IOBC category 2) to this phytoseiid predator.     

两种猎物对南方小花蝽种群增长的影响及其对二斑叶螨的控害潜能

南方小花蝽(半翅目:花蝽科)是农田害虫的重要天敌之一。在室内,分别用米蛾卵和二斑叶螨饲养南方小花蝽,采用生命表与功能反应方法,探讨了两种猎物(米蛾卵、二斑叶螨)对南方小花蝽种群增长的影响、评价了南方小花蝽应用前景。南方小花蝽取食米蛾卵的年龄特征生命表的参数如下:世代平均历期T= 24.3500d,雌性比率P_♀=0.5250,单雌平均产卵量FP_F=37.2857头,种群趋势指数(I)=9.2118,周限增长率λ＝1.0955,内禀增长率r_m＝0.0912。取食二斑叶螨的南方小花蝽能完成发育,雌雄可交配,但不能产卵。一龄若虫的存活率为81.19%,低于其它龄期的若虫存活率(89.5%以上)。从初孵若虫至成虫死亡,平均历期为19.3716d。取食米蛾卵的南方小花蝽成虫存活率为83.33%,而取食二斑叶螨的成虫存活率为59.68%;取食米蛾卵的南方小花蝽若虫平均历期(11.0633d)短于取食二斑叶螨的(13.8950d);然而取食米蛾卵的南方小花蝽成虫平均历期(9.9750d)明显长于取食二斑叶螨的(5.7297d)。表明米蛾卵能够满足南方小花蝽生长发育的营养需求,可以用来室内饲养南方小花蝽,二斑叶螨室内不能单独用于饲养南方小花蝽。南方小花蝽成虫对二斑叶螨成螨捕食功能反应符合HollingⅡ模型,且处置时间Th=0.0108,瞬间攻击率a=0.8253,日最大捕食量Na_max =92.59 d^-1。南方小花蝽是二斑叶螨潜在的生物防治资材。     

南方小花蝽对不同猎物捕食作用及利用效率

室内用棉蚜,花蓟马及棉花花粉饲养南方小花蝽,通过对南方小花蝽捕食两种猎物及取食棉花花粉后的体重的增长以及同时段内对棉蚜,花蓟马及棉花花粉减少的量的测定,得到南方小花蝽取食不同食物后的生长速率及其对食物的利用效率,同时还研究了南方小花蝽成虫和若虫对混合猎物（棉蚜,棉铃虫卵,红铃虫卵）中各猎物的捕食作用及其在多猎物（红铃虫卵,棉叶螨成螨,花蓟马若虫）不同密度水平下的捕食效应。结果表明,棉蚜与花蓟马可以较好地满足南方小花蝽正常生长发育所需的营养,南方小花蝽对两种猎物的利用效率显著高于棉花花粉,在混合猎物中南方小花蝽成虫和若虫均嗜食棉蚜,其次为红铃虫卵和棉铃虫卵;对于同一种猎物,南方小花蝽成虫和若虫在高密度下的日平均捕食量均显著高于低猎物密度下的日平均捕食量,而对于同一密度的不同猎物,南方小花蝽在低猎物密度时对供试的3种猎物无明显的选择性,在中,高密度时对供试的3种猎物则表现出明显的嗜食性差异。其嗜好程度依次为红铃虫卵,花蓟马若虫,棉叶螨成螨,通过研究有助于更好地了解与掌握南方小花蝽对不同食物的需求及其在田间的食物转换规律,从而更好地进行南方小花蝽的室内人工大量饲养,使南方小花蝽更好地成为棉田害虫种群综合治理中的重要组成部分并发挥其应有的作用。     

东亚小花蝽对西方花蓟马和二斑叶螨的捕食选择性

多食性天敌对猎物的捕食选择性及猎物密度对天敌捕食的干扰作用直接影响到天敌对不同猎物的控制作用.在实验室条件下研究了东亚小花蝽对西方花蓟马和/或二斑叶螨不同虫态的捕食选择性,以及两猎物中一种猎物的密度变化对小花蝽取食另一种猎物的影响.结果如下:东亚小花蝽5龄若虫和成虫对西方花蓟马2龄若虫的捕食选择性均强于对其成虫,对二斑叶螨的选择性为雌成螨>若螨>幼螨.实验中西方花蓟马2龄若虫是东亚小花蝽最喜好的虫态.二斑叶螨雌成螨密度固定为60头/19.63cm2,西方花蓟马若虫密度从10增加到60时显著地减少了东亚小花蝽对二斑叶螨的取食.反之,固定西方花蓟马同样密度,增加二斑叶螨密度却没有显著改变小花蝽对西方花蓟马的取食.此结果进一步表明,西方花蓟马是东亚小花蝽更喜好的猎物.