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Trialeurodes vaporariorum Westwood (greenhouse whitefly) are worldwide polyphagous pests of economic importance that damage solanaceous vegetables. Neonicotinoid pesticides and parasitoid Encarsia formmosa Gahan are the main management strategies applied worldwide, but precise control methods in greenhouse vegetables need to be developed to reduce the application amounts of pesticides and improve the suppression of whitefly populations. Therefore, we assessed the indoor acute toxicities and risk assessment of neonicotinoids for T. vaporariorum and E. formosa adults and pupae and compared the control effects of E. formosa and neonicotinoid acetamiprid. According to the acute toxicities results, most neonicotinoid insecticides were more toxic to E. formosa than T. vaporariorum, and pupae were much less susceptible than adults of both species. Moreover, acetamiprid had a low risk effect on E. formosa. Sole application of E. formosa and acetamiprid could effectively control T. vaporariorum, but their combined application resulted in antagonistic effects on the control of T. vaporariorum. The results showed that a combined application or sole use of E. formosa could reduce the use of insecticides, slow down the development of insecticide resistance in whiteflies, and improve the efficiency of controlling the growth of whitefly populations in greenhouse vegetable production. [ABSTRACT FROM AUTHOR]

کاربرد آفت­کش­ها رویکرد اصلی برای مدیریت سفیدبالک گلخانه Trialeurodes vaporariorum می باشد، بر این اساس اثر حشره­کش­های آزادیراختین، اسپیرومسیفن و تیامتوکسام روی سفیدبالک و زنبور پارازیتوئید آن Gahan Encarsia formosa مورد بررسی قرار گرفت. در ارزیابی میزان کشندگی تیمارها روی مراحل تخم و پوره سن سوم سفیدبالک بیشترین اثر کشندگی به ترتیب مربوط به اسپیرومسیفن در مرحله تخم با LC50 معادل 55/89 و تیامتوکسام در پوره سن سوم با LC50معادل 25/76 بود. نتایج حاصل از تجزیه واریانس تلفات تیمارها روی زنبور پارازیتوئید E. formosa بعد از هفت روز نشان داد که آزادیراختین دارای کمترین اثر سوء با 60 درصد ظهور زنبورها و تیامتوکسام بیشترین اثر سوء با 12درصد ظهور را داشت. در ارزیابی ترجیح تخم­ریزی زنبور E. formosa در بین تیمار حشره کش­ها علی­رغم تخم­ریزی بالای زنبور پارازیتوئید در دزهای پایین تیامتوکسام و اسپیرومسیفن ولی بیشترین تفریخ تخم مربوط به آزادیراختین بود. همچنین در ارزیابی کارآیی حشره‌کش­ها در گلخانه، علیه پوره سفیدبالک درصد تاثیر تیمارها در فواصل زمانی سه، هفت و 14 روز پس از سمپاشی نشان داد بیشترین اثر روی جمعیت پوره در سه روز پس از سمپاشی با80 درصد مرگ و میر مربوط به تیمار تیامتوکسام ولی در روز هفتم و چهاردهم پس از سمپاشی، بترتیب با 47/96 و 77/95% مرگ و میر مربوط به آفت‌کش گیاهی آزادیراختین بود. با توجه به نتایج این تحقیق در جمعیت بالای این آفت اسپیرومسیفن و تیامتوکسام موثر واقع شدند اما در برنامه مدیریت تلفیقی این آفت استفاده هم­زمان زنبور E. formosa با سم گیاهی آزادیراختین قابل توصیه می­باشد.

Chemosensory proteins (CSPs) perform several functions in insects. This study performed the gene expression, ligand-binding, and molecular docking assays on the EforCSP3 identified in the parasitoid wasp Encarsia formosa, to determine whether EforCSP3 functions in olfaction, especially in host location and host preference. The results showed that EforCSP3 was highly expressed in the female head, and its relative expression was much higher in adults than in other developmental stages. The fluorescence binding assays suggested that the EforCSP3 exhibited high binding affinities to a wide range of host-related volatiles, among which dibutyl phthalate, 1-octene, β-elemene, and tridecane had the strongest binding affinity with EforCSP3, besides α-humulene and β-myrcene, and should be assessed as potential attractants. Protein structure modeling and molecular docking predicted the amino acid residues of EforCSP3 possibly involved in volatile binding. α-Humulene and β-myrcene attracted E. formosa in a previous study and exhibited strong binding affinities with EforCSP3 in the current study. In conclusion, EforCSP3 may be involved in semiochemical reception by E. formosa.

Abstract Background The greenhouse whitefly, Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae) constitutes key pests of greenhouses and field crops, which have developed pesticide resistance over the years. It has emerged as a difficult pest to manage owing to its indiscriminate exposure to higher dosages of insecticides. The use of natural enemies is environmentally safe alternative management tactic. Efficacy of Encarsia formosa Gahan (Hymenoptera: Aphelinidae) was determined by studying its biological characteristics on T. vaporariorum. Results Parasitization by E. formosa was higher on fourth-instar nymphs of the greenhouse whitefly (GHWF) (37.2%), which was at par with that of third instar (36.4%), both differing significantly to the parasitization observed in second instar (19.6%). Total developmental duration of the parasitoid was longer on second instar (33.2 days) than that of fourth instar (29.9 days). Adult longevity was found significantly higher for the adults that emerged from fourth-instar nymphs of GHWF, which was at par to that of third instar and longevity of E. formosa adults was significantly higher in the absence of parasitoid host. The size of parasitoid that emerged from different instars of GHWF varied non-significantly. T. vaporariorum was reared on brinjal, cucumber, French bean, lettuce, tobacco, and tomato plants for mass production of E. formosa. Among them, French bean and tobacco were found to be the best host plants for mass production of E. formosa based on higher parasitization (37.2%). Total developmental period varied from 26.4 to 27.3 days on different host plants, the variations being non-significant. The maximum adult longevity was observed on cucumber (8.0 days) in the absence of host, and the adult size of parasitoid varied non-significantly. Results on host to parasitoid ratio of 5:1, 10:1, 20:1, 40:1 and 80:1 revealed that parasitization rate varied from 61.2 to 95.0% with maximum parasitization recorded in host–parasitoid proportion of 20:1 and minimum in 80:1. The total developmental duration varied non-significantly among all the proportions (15.1–15.4 days). Adult longevity was higher in the proportion of 40:1 (6.5 days), which was at par to the proportion of 5:1 (6.2 days), 20:1 (6.2 days), 80:1 (6.2 days) and 10:1 (6.1 days) in the absence of the host, respectively. Conclusion This study suggests that augmentative biological control of T. vaporariorum under polyhouse conditions with E. formosa appears to be an effective strategy for the management of this economic pest.

The role of selective new generation bioisecticides, beside their effectiveness against key pests, relies on their safety to beneficial arthropods. Spinetoram, a semi-synthetic analogue of the microbial-derived bioinsecticide spinosad is registered worldwide for application in numerous crops, but assessment of its ecotoxicological risk to beneficial arthropods has scarcely been documented. Moreover, this is the first report on toxic effects of spinetoram on a pest, the greenhouse whitefly Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae), and/or its successful biocontrol agent, the parasitoid Encarsia formosa Gahan (Hymenoptera: Aphelinidae). Under laboratory conditions, we assessed the acute toxicity of spinetoram insecticide (25% a.i.) to adults, nymphs and eggs of the greenhouse whitefly, as well as to parasitoid adults and pupae. In all concentration-response bioassays, the spinetoram insecticide was applied to tobacco leaves settled onto 1% agar layer in ventilated Petri dishes using a Potter spray tower. The parameters of spinetoram acute toxicity to adults of both the pest and the parasitoid were evaluated in residual contact bioassays, while whitefly eggs and nymphs, and parasitoid pupae were topically treated with a series of spinetoram concentrations, covering a range of 10-90% mortality. Lethal spinetoram effects on the parasitoid E. formosa were assessed through selectivity ratio (SR) estimations, showing the ratios beetween median lethal concentrations (LC50s) estimated for the parasitoid, and LC50s estimated for the pest. The following LC50 values were obtained: 4.593, 15.027 and 11.73 mg A.I./l for whitefly adults, nymphs and eggs, respectively, and 0.686 and 1.715 mg A.I./l for parasitoid adults and pupae, respectively. The calculated SR estimations were below 1, indicating that spinetoram insecticide is non-selective to both tested stages of the parasitoid E. formosa. A more detailed understanding of spinetoram impact on E. formosa in whitefly integrated management requires further evaluation of sublethal effects and greenhouse trials, with an emphasis on population-level responses.

Encarsia formosa is a natural enemy of the invasive pest Bemisia tabaci and is known to be a dominant parasitic. The frequency and magnitude of climate extremes, particularly temperature extremes, have increased, which has put insect populations at risk. However, the effects of temperature extremes on E. formosa are not well understood. To examine the impact of short-term extreme temperature exposure on the development and reproduction of E. formosa, eggs, larvae, pupae, and adults were exposed to high/low temperature treatments (HLT25, HLT50, LLT25, and LLT50). Our findings indicate that the pupal stage of E. formosa exhibited the strongest tolerance to both heat and cold, while adults exhibited a weaker tolerance. The shortest egg-to-adult development period of 12.65 days was observed in E. formosa exposed to HLT50 treatment during the egg-larval stage. The parasitism peak of the adult stage was delayed by 1–6 days after exposure to extreme temperatures during the egg-larval stage. Conversely, the parasitism peak was advanced by 1–3 days after exposure to extreme temperatures during the pupal and adult stages. The eclosion rate, total parasitism, eclosion rate of the F1 generation, and adult longevity of the F1 generation were lower in the treatment groups than in the control groups. The F1 generation’s development period was prolonged to 15.49 and 15.19 days after exposure to HLT25 and HLT50 treatments, respectively, during the egg-larval stage. The F1 generation’s development period was shortened to 13.33 days after exposure to LLT50 treatment during the pupal stage. Male individuals appeared in the F1 generation after exposure to HLT50 treatment during the pupal stage, with females accounting for only 56.38%. Our results demonstrate that short-term exposure to extreme temperatures has detrimental effects on the growth and reproduction of E. formosa. In field biocontrol against E. formosa, the release of E. formosa should be avoided as much as possible when the ambient temperature is higher than 35°C or lower than 0°C. During extreme temperature conditions, timely supplementation and release of E. formosa population, along with ventilation and cooling in greenhouse facilities during summer, are necessary for better pest control efficacy [ABSTRACT FROM AUTHOR]

The predator Tupiocoris cucurbitaceus (Spinola) and the parasitoid Encarsia formosa Gahan are natural enemies of Trialeurodes vaporariorum (Westwood) that can be found simultaneously in greenhouse tomato crops. Whether or not these species are involved in a trophic interaction with each other, and how this interaction might impact the control of the whitefly population has not been explored so far. In the present study, we evaluate the consumption and preference of T. cucurbitaceus for parasitized and nonparasitized T. vaporariorum nymphs. Furthermore, the effect that the joint presence of both natural enemies can have on the control of the whitefly population. Our results show that under laboratory conditions T. cucurbitaceus females engage in intraguild predation on E. formosa pupae. However, given the choice, the predator prefers to prey on healthy T. vaporariorum nymphs. Under greenhouse conditions, however, both T. cucurbitaceus and E. formosa reduce whitefly population when released separately, and their control is enhanced when released together. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agricultural Science & Technology (1008-0864) is the property of Journal of Agricultural Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Applied Entomology is the property of Chinese Journal of Applied Entomology, Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Intracellular bacterial endosymbionts of arthropods are mainly transmitted vertically from mother to offspring, but phylogenetically distant insect hosts often harbor identical endosymbionts, indicating that horizontal transmission from one species to another occurs in nature. Here, we investigated the parasitoid Encarsia formosa-mediated horizontal transmission of the endosymbiont Rickettsia between different populations of whitefly Bemisia tabaci MEAM1. Rickettsia was successfully transmitted from the positive MEAM1 nymphs (R+) into E. formosa and retained at least for 48 h in E. formosa adults. Fluorescence in situ hybridization (FISH) visualization results revealed that the ovipositors, mouthparts, and digestive tract of parasitoid adults get contaminated with Rickettsia. Random non-lethal probing of Rickettisianegative (R-) MEAM1 nymphs by these Rickettsia-carrying E. formosa resulted in newly infected MEAM1 nymphs, and the vertical transmission of Rickettsia within the recipient females can remain at least up to F3 generation. Further phylogenetic analyses revealed that Rickettsia had high fidelity during the horizontal transmission in whiteflies and parasitoids. Our findings may help to explain why Rickettsia bacteria are so abundant in arthropods and suggest that, in some insect species that shared the same parasitoids, Rickettsia may be maintained in populations by horizontal transmission. [ABSTRACT FROM AUTHOR]

سفیدبالک گلخانه (Trialeurodes vaporariorum West) به عنوان آفتی پلی‌فاژ با تعداد نسل زیاد، یکی از آفات مهم گیاهان زینتی و گلخانه‌ای است. در این تحقیق مقایسه سمیت امامکتین، اسپینوزاد، بوپروفزین و ایمیداکلوپراید روی سفیدبالک و زنبور پارازیتوئید آن مورد بررسی قرار گرفت. مقادیر LC50 حاصل از تجزیه پروبیت داده­ های زیست­سنجی در نتیجه‌ی تاثیر غلظت ‏های مختلف امامکتین، اسپینوزاد، بوپروفزین و ایمیداکلوپراید روی پوره سن سوم سفیدبالک بعد از 24، 48 و 72 ساعت به ترتیب (72/1، 33/1، 31/1 و 63/0)، (40/1، 31/1، 27/1 و 44/0) و (15/1، 04/1، 93/0 و 31/0) میلی لیتر بر لیتر به دست آمد. طبق این نتایج موثرترین حشره‏ کش روی پوره سن سوم سفیدبالک گلخانه طی 24، 48 و 72 ساعت ایمیداکلوپراید و کم ­اثرترین حشره‏ کش، امامکتین بود. نتایج تجزیه واریانس و مقایسه میانگین‏ های تلفات ناشی از تیمارهای امامکتین، اسپینوزاد، بوپروفزین و ایمیداکلوپراید روی زنبور پارازیتوئید انکارسیا بعد از 5 روز نشان داد که حشره ‏کش بوپروفزین کم ­خطرترین و ایمیداکلوپراید پرخطرترین حشره‏ کش برای این دشمن طبیعی است. بنابراین، در مدیریت تلفیقی این آفت با توجه به کم­اثر بودن بوپروفزین روی زنبور E. formosa در مقایسه با سایر حشره‏ کش ‏ها و نیز داشتن سمیت بالا روی مراحل تخم و پوره سن سوم آفت قابل توصیه می باشد.

Abstract Background The greenhouse whitefly, Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae), is a cosmopolitan, polyphagous and a serious pest of vegetables and ornamentals in greenhouse. Encarsia formosa Gahan (Hymenoptera: Aphelinidae) is an important primary endoparasitoid species of the greenhouse whitefly. Results In the present study, per cent parasitisation attained 50% on the 4th instar and 46% on the third 3rd instar of T. vaporariorum by E. formosa. The mean duration period of the parasitoid from egg to host mummification, mummification to adult emergence (pupal period) was 11 and 7.8 days on 3rd instar and 8.5 and 7.6 days on 4th instar, respectively. The total time period from egg to adult emergence reached 18.8 days on 3rd instar and 16.2 days on 4th instar. Longevity of the female parasitoids was 8.3 and 8.8 days on 3rd and 4th instars, respectively. The pre-ovipositional, ovipositional and post-ovipositional periods of the parasitoid were 1.2, 6.4 and 1.0 days on 3rd instar and 1.2, 6.7 and 1.0 days on 4th instar, respectively. The finite rate of natural increase (λ), doubling time and weekly multiplication rate of the 3rd instar was 1.16±0.002 times per day, 4.71±0.04 days and 2.80±0.03 folds, respectively and 1.17±0.002 times per day, 4.34±0.04 days and 3.06±0.03 folds for the 4th instar. Conclusions Studies indicated that the 4th nymphal instar of the host was more suitable for parasitisation with E. formosa. The parasitoid species could be mass multiplied and utilised as a component of integrated pest management programme of T. vaporariorum after evaluation under field conditions.

The abandonment of insecticide treatments to achieve sustainable crop production calls for a combination of methods to obtain satisfactory pest control. To this end, net houses and biological control are two promising methods, though we suspected that most natural enemies are blocked outside the net houses. In Kenya, tomato crops are particularly threatened by Trialeurodes vaporariorum (Westwood 1856) and Tuta absoluta (Meyrick, 1917) that are targets of most insecticide treatments in this country. We investigated in an on-farm experiment (i) the abundances of T. vaporariorum and T. absoluta in open fields and in net houses, (ii) the diversity of arthropod natural enemies of these pests, and (iii) the effect of net houses on the natural regulation. To complete, in the laboratory, we checked the capacity of natural enemies to pass through different net types. We identified several natural enemies, mainly the mirid bug Nesidiocoris tenuis (Reuter 1895) that was the most abundant predator for both pests. One parasitoid species was also identified for each pest, i.e. Encarsia formosa Gahan (1924) and Copidosoma sp. for T. vaporariorum and T. absoluta respectively. Net houses reduced drastically the pest populations. Predators were less abundant under net houses, while parasitoids did not seem to be affected by the nets. Encarsia formosa was shown to be able to pass through the different net types, while N. tenuis adults were not. These results raise the potential for augmentative biological control under net houses. Using kairomones to attract natural enemies, or introducing natural enemies under the net houses through inoculative releases, are two approaches to increase the abundance of natural enemies under net houses. [ABSTRACT FROM AUTHOR]

Banker plants increase biological pest control by supporting populations of non-pest arthropod species, used as alternative hosts or prey by natural enemies. Due to the specificity of trophic interactions, banker plants may not efficiently promote natural enemies with different ecologies. Yet in most cropping systems, different pest species are present together and require different biocontrol agents to efficiently control them. In the present study, we tested the combined use of two banker plants and their associated prey/host to enhance populations of the specialist parasitoid Encarsia formosa targeting the main tomato pest Bemisia tabaci, and a polyphagous ladybird Propylea japonica targeting the secondary pest Myzus persicae in tomato crops. In a laboratory and a greenhouse experiment, we measured the abundances of these four species using the Ricinus communis—Trialeurodes ricini banker plant system alone, in combination with the Glycines max—Megoura japonica system, or in absence of banker plants. We found that the first banker plant system enhanced populations of E. formosa, resulting in increased suppression of B. tabaci populations and the suppression of their outbreak in both our laboratory and greenhouse experiment. Conversely, abundances of P. japonica were not affected by this first system, but were significantly increased when the second was present. This resulted in increased control of M. persicae populations and the suppression of their early and late outbreaks. Our study demonstrates the potential for combined banker plants to provide long-term, sustainable control of multiple pests by their target natural enemies in complex agroecosystems. [ABSTRACT FROM AUTHOR]

The impact of predatory or parasitic natural enemies on their pest prey or hosts arises not only through consumption but also through non-consumptive effects. Multiple studies have investigated the impacts of non-consumptive effects from predators on the behaviour, development and metabolism of invertebrate pests. However, the non-consumptive effects from parasitoids on their insect hosts remain less well understood. Here, we investigated the non-consumptive effects of the parasitoid Encarsia formosa on the fecundity, longevity and metabolism of the whitefly Bemisia tabaci. Results showed that both the fecundity and longevity of whitefly females were significantly reduced when the whiteflies were threatened by Encarsia parasitoids during their nymphal stages. In addition, we tested three costly and potential physiological correlates that may contribute to the fecundity and longevity variation of B. tabaci under the non-consumptive effects: the relative expression level of vitellogenin and its receptor genes (Vg and Vgr), relative expression level of stress proteins (Hsp70 and Hsp90) and the activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD). When B. tabaci 4th instar nymphs were threatened for 24 h by E. formosa the relative expression levels of Vg and Vgr were reduced, whereas Hsp70 and Hsp90 were significantly increased. SOD and CAT activities were distinctly up-regulated while POD activity was down-regulated. We propose that, in order to counteract the negative effects of non-consumption, whitefly nymphs need to adjust their performance by changing the expression of related metabolic genes in an energetic cost way, thus reducing the fecundity and longevity of female adults. [ABSTRACT FROM AUTHOR]

The phytophagous whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) causes serious crop yield losses around the world especially by vectoring viruses. Exogenous jasmonic acid (JA) induces direct plant resistance to B. tabaci, but the underlying mechanism of JA‐induced exogenous defenses is not well understood. Here, we demonstrate that exogenous JA not only increases the cytosolic Ca2+ concentration ([Ca2+]cyt) in tomato mesophyll cells but also induces the expression of Ca2+‐sensor genes and plant defense genes. Pre‐treatment with Ca2+ inhibitor (ruthenium red) significantly repressed the elevation of [Ca2+]cyt, expression of JA‐induced genes, and emission of plant volatiles induced by JA, thus reducing the JA‐induced direct (feeding choice and fitness of B. tabaci) and indirect [olfactory choice and parasitism by the parasitoid Encarsia formosa Gahan (Hymenoptera: Aphelinidae)] plant resistance to B. tabaci. These results indicate that the Ca2+ signal induced by JA mediates and directs the plants defenses against whitefly. Present results will not only give us a better understanding of how exogenous JA influences the crop community, but also deliver some clues for the potential application of exogenous JA, as a plant elicitor, in whitefly management. [ABSTRACT FROM AUTHOR]

Sublethal effects of a pymetrozine-based product (commercial product Chess 50 WP) on life history traits and population growth of one commercialized strain ("Dutch" strain) and two local populations (Bujanovac and Negotin) of the whitefly parasitoid Encarsia formosa Gahan (Hymenoptera: Aphelinidae) were evaluated in laboratory bioassays. All trials were carried out at 27±1°C temperature and under 60±10 % relative humidity and 16/8 h daylight/darkness photoperiod in four replications. Longevity of wasps exposed for 48 h to residues of the pymetrozine insecticide (LC 50 , 280 mg A.I./l) was shorter (by 2.7-3 days) than that of control wasps. Total parasitism of Negotin wasps was significantly reduced (by 8.2 %), as well as total parasitism and adult emergence of the Dutch strain (by 7.3 and 8.2 %, respectively), compared to control wasps. The instantaneous rate of increase (r i) of surviving adult wasps was also significantly reduced (by 6.6, 6.3 and 7.6 % in populations Negotin, Bujanovac and Dutch strain, respectively). Direct treatment of wasps at their pupal stage (LC 50 , 300 mg A.I./l) reduced total parasitism of Negotin wasps (by 8 %), and reduced r i levels, but the reduction was significant only for the Bujanovac (by 6.7 %) and Negotin (by 4.6 %) populations. Juvenile development of the parasitoid in treated pupae was significantly extended (by 0.3-1.1 days), compared to control wasps. The implications of these results on integrated control of the greenhouse whitefly are discussed.

When zoophytophagous mirids (Hemiptera: Miridae) feed on tomato plants they activate both direct and indirect defense mechanisms, which include the release of herbivore induced plant volatiles (HIPVs). HIPVs are capable of activating defense mechanisms in healthy neighboring plants. In this work, we investigated which of these mirid-induced HIPVs are responsible for inducing plant defenses. Healthy tomato plants were individually exposed to eight HIPVs [1-hexanol, (Z)-3-hexenol, (Z)-3-hexenyl acetate, (Z)-3-hexenyl propanoate, (Z)-3-hexenyl butanoate, hexyl butanoate, methyl jasmonate and methyl salicylate] for 24 hours. Then, the expression level of defensive genes was quantified. All HIPVs led to increased expression of defensive genes by the plant when compared to unexposed tomato plants. In a further step, (Z)-3-hexenyl propanoate and methyl salicylate were selected to study the response of four tomato key pests and one natural enemy to tomato plants previously exposed to both HIPVs relative to unexposed control plants. Plants previously exposed to both HIPVs were repellent to Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) and Frankliniella occidentalis Pergande (Thysanoptera: Thripidae), attractive to the parasitoid Encarsia formosa Gahan (Hymenoptera: Aphelinidae) and indifferent to Tetranychus urticae Koch (Acari: Tetranychidae). The volatiles emitted by plants previously exposed to both selected volatiles were also determined. Increased levels of C5 and C6 fatty acid-derived volatile compounds and ß-ionone were detected, confirming that both HIPVs significantly activated the lipoxygenase pathway. These results are the starting point to advance the use of volatile compounds as defense elicitors in tomato crops. [ABSTRACT FROM AUTHOR]

Acute toxicity of a buprofezin-based product (commercial product Elisa 440 SC) to pupae of the whitefly parasitoid Encarsia formosa Gahan (Hymenoptera: Aphelinidae), and its effects on life history traits and population growth in F1 generation of a commercial strain ("Dutch" strain, D) and two local populations from Serbia (Bujanovac, B; Negotin, N) were examined in laboratory bioassays. All trials were carried out at 27±1°C temperature and 60±10% relative humidity, and under 16/8 h daylight/darkness photoperiod in four replications. In an acute toxicity bioassay, tobacco leaves carrying parasitoid pupae (20 pupae per replicate) were treated with a series of buprofezin concentrations covering a 10-90% mortality range, and mortality was calculated based on the number of emerging adults 9 days after treatment. The following LC50 (mg/l) estimates were obtained: 244.2, 281.5 and 199.5 (for B, N and D, respectively). The product based on buprofezin, applied to parasitoid pupae at concentrations within the LC50s and 95% confidence limits (264 mg/l for B and N; 220 mg/l for D), significantly prolonged the duration of juvenile development (2, 1.7 and 2.2 days for B, N and D, respectively, compared to control data). Females from all tested populations that emerged from the treated pupae and were exposed to the residual action of buprofezin lived shorter than control females (B, N and D by 1.5, 0.7 and 1.7 days, respectively). Also, females that emerged from the treated pupae achieved a significantly reduced level of parasitism (B, N and D by 11.7, 17.7 and 17.6 %, respectively), total adult emergence (B, N and D by 11.6, 17.8 and 17.8 %, respectively) and instantaneous rate of increase (B, N and D by 8.2, 6.8 and 12.5 %, respectively), compared to control. More precise determination of risks involved in the use of buprofezin requires its more detailed field testing.

تأثیر سه گیاه میزبان خیار، گوجه‏فرنگی و بادمجان روی واکنش تابعی زنبور پارازیتوئید Encarsia formosa نسبت به تراکم‏های مختلف پوره‏های ابتدای سن چهارم سفیدبالک گلخانه Trialeurodes vaporariorum در شرایط آزمایشگاهی (دمای 1±25 درجه‏ی سلسیوس، رطوبت نسبی 5±65 درصد و دوره‏ی نوری 16 ساعت روشنایی و 8 ساعت تاریکی) مورد بررسی قرار گرفت. پوره‏های سفیدبالک در تراکم‎های 2، 4، 8، 16، 32 و 48 روی دیسک‏های برگی به مساحت تقریبی 8 تا 10 سانتی‏متر مربع در 12 تکرار در اختیار حشرات ماده‏ی پارازیتوئید قرار گرفت. پس از 24 ساعت پارازیتوئیدها حذف و تعداد پوره‏های پارازیته شده و نیز کشته شده در اثر میزبان‏خواری به تفکیک شمارش و ثبت شد. نتایج رگرسیون لجستیک نشان داد که واکنش تابعی پارازیتوئید برای هر دو نوع فعالیت "پارازیتیسم" و " پارازیتیسم+ میزبان‎خواری" در هر سه گیاه میزبان از نوع دوّم است. برای هر دو فعالیت مورد مطالعه از نظر نرخ حمله بین سه میزبان گیاهی اختلاف معنی‏داری وجود نداشت، اما زمان دستیابی روی گوجه‌فرنگی به‏طور معنی داری از مقادیر محاسبه شده در خیار کوتاه‏تر بود. قدرت جستجوگری زنبور E. formosa در مرحله‏ "پارازیتیسم" در میزبان‏های مذکور به ترتیب 0963/0±2580/0، 1331/0±3895/0 و 1368/0±3283/0 برساعت و زمان دستیابی 0810/0±6870/0، 0399/0±3364/0 و 0692/0±5584/0 ساعت محاسبه شد. بر اساس نتایج به‏دست آمده به‏نظر می‏رسد در شرایط گلخانه‏ای، گوجه‏فرنگی مناسب‏ترین گیاه برای فعالیت‏های پارازیتیسم و میزبان‏خواری زنبور پارازیتوئید E. formosa در کنترل سفیدبالک گلخانه T. vaporariorum باشد.

The parasitoid of whiteflies Encarsia formosa has been widely applied to reduce whitefly-mediated damage on vegetables and ornamental plants grown in greenhouses. Although its chemosensory behavior has been described, the mechanism by which E. formosa recognizes chemical volatiles at the molecular level remains unknown. In this study, we obtained 66,632 unigenes from antennae transcriptomic architecture of E. formosa , of which 19,473 (29.2%) were functionally annotated. All that matters is that we manually identified 39 odorant-binding proteins (OBPs) from above dataset, and further investigated the tissue and stage-specific expression profiles of all identified OBP genes by real-time quantitative PCR. Among these OBP genes, 32 were enriched in antennae, and 2 in body. In addition, 4 OBPs were highly expressed in pupae, and 32 in 6-hour-age adults after eclosion. In addition to identifying OBP genes from E. formosa , this study provides a molecular basis for further functional studies of OBPs and the interactions of hosts and parasitic wasps. • Total 66,632 unigenes were obtained and 19,473 were annotated. • Total 295 olfactory-related genes were identified. • Total 39 odorant-binding proteins were cloned and analyzed. • Total 32 OBPs were highly expressed in antennae and adult stage for E. formosa. [ABSTRACT FROM AUTHOR]

Encarsia formosa Gahan is an important endoparasitoid of the whitefly, Bemisia tabaci Gennadius. In the present study, we compared the fitness and population parameters of E. formosa when parasitizing the two most invasive and destructive whitefly species in China, the B and Q of B. tabaci. We also studied whether natal host influenced on parasitism and host-feeding capacities of E. formosa on B. tabaci B versus Q. Age–stage life table analysis indicated that E. formosa developmental duration was shorter, fecundity was higher, and longevity was greater on B. tabaci B than on Q. The life table parameters, including the intrinsic rate of increase (r), finite rate of increase (λ), net reproduction rate (R 0), and the mean generation time (T), indicated that the fitness of E. formosa on B. tabaci B is higher than B. tabaci Q. We also found that the host species used to rear E. formosa affected the parasitoid's subsequent parasitism and host feeding on B. tabaci B and Q. When E. formosa were reared on B. tabaci B, its subsequent parasitism rate on third-instar nymphs was significantly higher on B. tabaci B than on Q. These results will be useful for managing the biological control of B. tabaci in the field. [ABSTRACT FROM AUTHOR]

[Objectives] To investigate the impact of Rickettsia infection on the resistance of the whitefly Bemisia tabaci to the parasitoid wasp Encarsia formosa, and provide new strategies for whitefly management. [Methods] The parasitism rate, developmental period, eclosion rate, body size (body length, body width, head length and head width) and the host preferences of E. formosa for different B. tabaci hosts, were investigated in both Rickettsia positive and negative populations of B. tabaci (B-biotype) and its parasitoid E. formosa. [Results] Rickettsia infection had a significant effect on the parasitism rate and developmental period of E. formosa, but no significant effects on the eclosion rate and body size of F1 generation adults. The average parasitism rates of E. formosa on Rickettsia positive and negative B. tabaci nymphs was 32.52% and 41.50%, respectively, and the developmental periods of these two populations were 14.5 d and 15.0 d, respectively. The eclosion rates of F1 generation E. formosa adults raised on either Rickettsia positive or Rickettsia negative B. tabaci nymphs, were 79.02% and 83.71%, respectively; the body length, body width, head length, and head width of F1 generation E. formosa adults raised on Rickettsia positive hosts were slightly larger than those of wasps raised on Rickettsia negative hosts. In laboratory choice experiments, the average parasitism rates of E. formosa on Rickettsia positive vs Rickettsia negative B. tabaci hosts were 35.26% and 50.22%, respectively. Under semi-field conditions, the average parasitism rates of E. formosa on Rickettsia positive populations was 35.03% in choice experiments; significantly lower than that on Rickettsia negative populations (57.79%). [Conclusion] Rickettsia infection reduces the susceptibility of B. tabaci to parasitism by E. formosa because E. formosa females prefer to parasitize Rickettsia negative B. tabaci, a preference that potentially increases the survival of their offspring. [ABSTRACT FROM AUTHOR]

The effects of a Beauveria bassiana-based product (trade name Naturalis-L; strain ATCC 74040) on the behaviour, life history traits and population growth of one commercial Dutch strain and two local Serbian populations (Bujanovac and Negotin) of Encarsia formosa Gahan (Hymen.: Aphelinidae) were evaluated in laboratory bioassays. In a two-choice test, parasitoids from all tested populations preferred to parasitise untreated whitefly nymphs over those treated with 1, 0.5, 0.25, 0.125 and 0.0625 ml/l of the mycopesticide. The longevity of adults of population Bujanovac exposed for 48 h to residues of the mycoinsecticide applied at the LC50 concentration was 1.4 days shorter than that of control wasps. Total parasitism was significantly reduced (by 17.5, 26.2 and 31.4% for the Negotin, Dutch and Bujanovac populations, respectively) compared to control, as well as adult emergence in the F1 generation (reductions of 20.3 and 26.7%, for the Dutch and Bujanovac populations, respectively). The instantaneous rate of increase (ri) of surviving adults was also significantly reduced by mycopesticide treatment by 6.3, 13.8 and 15.1%, for the Negotin, Bujanovac, and Dutch populations, respectively. Adult parasioids emerged from pupae treated with the LC50 concentration of the mycopesticide showed slower juvenile development, longevity, parasitism, adult emergence, and ri values, but the reduction in ri was significant only for the Bujanovac and Dutch populations (4.2 and 8.3%, respectively). The implications of these results on integrated control of the greenhouse whitefly Trialeurodes vaporariorum Westwood (Hem.: Aleyrodidae) are discussed in terms of adjusting the timing of Naturalis-L applications and parasitoid release. [ABSTRACT FROM AUTHOR]

Acute toxicity of an imidacloprid-based product (Confidor 200 SL) to pupae of the whitefly parasitoid Encarsia formosa Gahan (Hymenoptera: Aphelinidae), and its effects on life history traits and population growth in F1 generation of the surviving parasitoid females of a commercial strain ('Dutch' strain, D) and two local populations from Serbia (Bujanovac, B; Negotin, N) were examined in laboratory bioassays. All trials were carried out at 27±1°C temperature and 60±10% relative humidity, and under 16/8 h daylight/darkness photoperiod in four replications. In acute toxicity bioassays, tobacco leaves carrying parasitoid pupae were treated with a series of symmetrical concentrations (800, 400, 200, 100, 50 and 25 mg a.i./l) covering a 10-90% mortality range. The product based on imidacloprid, applied directly onto parasitoid pupae at mean lethal concentrations (LC50) determined in the acute toxicity assays (30 mg/l, 20 mg/l and 25 mg/l, for populations B, N and D, respectively), significantly affected the survival of females developed from the treated pupae, extended the duration of juvenile development (by 1.81, 1.59 and 1.73 days for populations B, N and D, respectively), significantly reduced total parasitism of females D (25.92 %), total female adult emergence in populations B (27.48 %) and D (17.92 %), and significantly reduced the instantaneous rate of increased only of females N (4.23 %). Considering the high acute toxicity of the imidacloprid product to the pupal stage of E. formosa, and significant reductions in life table and population parameters, imidacloprid is not considered compatible for simultaneous use with the parasitoid E. formosa. A more precise assessment of risks involved in the use of that insecticide requires a more detailed testing in the field. The implications of these results for the concept of integrated control of the greenhouse whitefly are discussed.

پاسخ بویایی و جهت‌گیری زنبورهای ماده (Encarsia formosa Gahan (Hymenoptera: Aphelinidae به سمت مواد فرار سفیدبالک گلخانه­ ی سالم و تیمار شده با قارچ Asc.: Clavicipitaceae) Lecanicillium longisporum) با استفاده از لوله ­ی بویایی ­سنج (الفکتومتر) Y شکل اندازه­ گیری شد. در پاسخ بویایی زنبور پارازیتوئید به رایحه­ های تیمار گیاه خیار آلوده به پوره­ های سفیدبالک در مقایسه با گیاه خیار سالم (بدون سفیدبالک و قارچ) و تیمار گیاه خیار آلوده به سفیدبالک در مقایسه با گیاه خیار آلوده به سفیدبالک تیمار شده با قارچ بیمارگر مشخص شد بین پارازیتوئیدهایی که هر یک از دو بازو را انتخاب می­کردند، تفاوت معنی­ داری وجود ندارد. پاسخ بویایی زنبور پارازیتوئید به رایحه­ های القایی تیمار گیاه سالم (بدون سفیدبالک و قارچ) در برابر هوای پاک و تیمار گیاه آلوده به سفیدبالک گلخانه در برابر هوای پاک، زنبور پارازیتوئید به صورت معنی­ داری به سمت بازویی جلب شد که به­ ترتیب حاوی گیاه سالم و آلوده به سفیدبالک بود. با توجه به نتایج آزمایش­ها در مجموع تیمارها می ­توان اظهار داشت علی­رغم اینکه پارازیتوئیدها در جلب به برخی از تیمارهای مورد مقایسه گرایش خاصی نشان می­دهند اما پاسخ مشخصی را به ترکیب گیاه- سفیدبالک در مقایسه با گیاه سالم نداده است. در واقع حضور سفیدبالک دلیلی برای گرایش زنبور پارازیتوئید به سمت میزبانش نیست.

The proliferation of sooty mold on tomato fruit, Solanum lycopersicum L.—as caused by the secretion of honeydew on the fruit by greenhouse whitefly, Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae)—has recently become a serious problem in estivo-autumnal greenhouse tomato cultivation in Japan. It is becoming increasingly difficult to control T. vaporariorum using insecticides because whiteflies have developed resistance to a variety of insecticides. As the first step towards integrated pest management, we examined whether the use of selective insecticides could prompt a cascade process in which an increase in parasitoids is followed by a decrease in whitefly occurrence and then a reduction in sooty mold damage. We compared greenhouses in which nonselective insecticides effective against T. vaporariorum and its parasitoids were used (hereafter denoted “nonselective insecticide greenhouses”) with greenhouses in which selective insecticides for T. vaporariorum were used (hereafter denoted “selective insecticide greenhouses”) in terms of the density and level of parasitism of T. vaporariorum as well as the degree of damage from sooty mold. The number of parasitized whiteflies increased with the number of whiteflies in the selective insecticide greenhouses, whereas it remained at low levels regardless of the number of whiteflies in the nonselective insecticide greenhouses. Furthermore, the selective insecticide greenhouses showed significantly higher parasitism levels, fewer whiteflies, and reduced sooty mold damage compared to the nonselective insecticide greenhouses. These results suggest that the use of selective insecticides causes an increase in parasitism, which in turn suppresses the number of greenhouse whiteflies and, eventually, sooty mold. [ABSTRACT FROM AUTHOR]

Encarsia formosa Gahan is a solitary endoparasitoid that is commercially reared and released for augmentative biological control of whiteflies including Bemisia tabaci (Gennadius). Bemisia tabaci biotypes B and Q are two most invasive species that greatly reduce crop yields in China by feeding on plant sap and by transmitting Tomato Yellow Leaf Curl Virus (TYLCV). The effects of TYLCV infection of tomato on E. formosa foraging on B. tabaci B and Q are unknown. In Y-tube olfactometer assays in the present study, E. formosa significantly preferred TYLCV-infected tomato plants over TYLCV-free plants. The wasp females also significantly preferred TYLCV-infected tomato plants infested with 3rd-instar nymphs of B. tabaci biotype Q over TYLCV-free plants with biotype Q nymphs. However, no significant differences were observed when B. tabaci biotype B was infested on tomato plants. The oviposition bioassays confirmed that TYLCV infection on tomato plants resulted in the recruitment of parasitoids. These results indicate that TYLCV-infection of tomato increase the foraging of E. formosa on B. tabaci , as differs on the B and Q biotypes. [ABSTRACT FROM AUTHOR]

The sweetpotato whitefly Bemisia tabaci (Gennadius) is one of the most invasive pest species worldwide. Q and B biotypes are the two most devastating species within the B. tabaci complex. Bemisia tabaci can vector hundreds of plant viruses that seriously threaten crop production. Endoparasitoid, Encarsia formosa Gahan, is widely used to control whiteflies, however, little is known about the effects of virus-infected plants on E. formosa parasitism of B. tabaci. Here, we reported that tomato, which was infected with Tomato Yellow Leaf Curl Virus (TYLCV), altered the host selection of E. formosa between B. tabaci Q and B biotypes. On healthy tomato plants, parasitism and host selection by E. formosa did not differ between the 3rd-instar nymphs of B. tabaci Q and B biotypes. On TYLCV-infected tomato plants, however, B. tabaci Q biotype were significantly more attractive to E. formosa than B biotype. When TYLCV-infected tomato plants were infested with B. tabaci Q or B biotype, volatile profiles differed quantitatively but not qualitatively. Olfactometer assays suggested that the preference of E. formosa to Q over B biotype was associated with an elevated level of β-Myrcene, β-Ocimene, β-Caryophyllene, and α-Humulene from TYLCV-infected tomato plants.

Although it is important to identify species of pest and natural enemy insects in agriculture, morphological identification alone is often difficult. Because a combination of morphological identification and DNA barcoding is very important for identifying indiscriminable species, there is a need to develop non-destructive DNA extraction methods. Here, we compared three general methods of DNA extraction-the Chelex method, PrepMan Ultra Reagent, and DNeasy Blood and Tissue Kit-in the search for a rapid, simple, and non-destructive method of DNA extraction from pest and natural enemy specimens. Amplification of PCR production was achieved with the Chelex method and the DNeasy Blood and Tissue Kit. However, not all specimens tested by the PrepMan Ultra Reagent method yielded amplification products. Observation of the morphological features of dried Encarsia formosa specimens revealed that all heads and leg segments remained intact after DNA extraction by each of the three methods. Almost all samples treated with the PrepMan Ultra Reagent method had large, discernible morphological changes, in particular, of the antennae and forewings, which are important features for identifying minute wasps. In contrast, the antennae and forewings of specimens on which we used the Chelex method suffered little damage. Use of the DNeasy Blood and Tissue Kit method did not alter the forewing features, but strong wrinkles appeared in the antennae. We discuss the DNA extraction techniques from the perspective of these results. [ABSTRACT FROM AUTHOR]

Encarsia formosa Gahan (Hymenoptera: Aphelinidae) is a solitary endoparasitoid that is commercially reared and released for augmentative biological control of whiteflies infesting greenhouse crops. In most areas in China, the invasive and destructive whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) biotype Q has replaced B. tabaci biotype B and has become dominant between the two. A better understanding of the suitability of different nymphal instars of B. tabaci biotypes Q and B as hosts for E. formosa is needed to improve the use of this parasitoid for biological control. Parasitism of the four nymphal instars of B. tabaci biotypes Q and B by the commercial strain of E. formosa mass reared on Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae) was assessed in the laboratory. The results indicated that E. formosa parasitized and successfully developed on all instars of both biotypes but performed best on the 3rd instar of B. tabaci biotype B and on the 2nd, 3rd, and 4th instars of B. tabaci biotype Q. The host-feeding rate of the adult parasitoid was generally higher on nymphal instars of B. tabaci biotype Q than on the corresponding nymphal instars of biotype B and was significantly higher on the 2nd and 3rd instars. For both whitefly biotypes, the parasitoid’s immature developmental period was the longest on the 1st instar, intermediate on the 2nd and 3rd instars, and the shortest on the 4th instar. The parasitoid emergence rate was significantly lower on the 1st instar than on the other three instars and did not significantly differ between B. tabaci biotype B and biotype Q. Offspring longevity was greater on the 3rd and 4th instars than on the 1st instar and did not significantly differ between the two B. tabaci biotypes. The results indicate that commercially-produced E. formosa can parasitize all instars of B. tabaci biotypes B and Q, making this parasitoid a promising tool for the management of the two biotypes of B. tabaci present in China.

تاثیر قارچ Lecanicillium longisporum روی توان تولید­مثلی زنبور پارازیتوئید Encarsia formosaدر شرایط آزمایشگاهی مورد مطالعه قرار گرفت. آلودگی قارچی با ­پاشش غلظت 105 × 5/9 کنیدی در میلی ­لیتر روی پوره سن سوم سفیدبالک گلخانه ایجاد شد و در چهار بازه زمانی صفر، 24، 48 و 72 ساعت پس از پاشش در اختیار زنبور پارازیتوئید قرار گرفت. طول عمر، دوره پیش از تخم­گذاری، طول مدت تخم­گذاری و سایر پارامترهای مهم جدول زندگی در تیمارهای مختلف پس از اسپور­پاشی مورد ارزیابی و مقایسه قرار گرفت. نتایج نشان داد که نرخ ذاتی افزایش جمعیت زنبور پارازیتوئید روی میزبان ­های سالم 203/0 بر روز بوده و در بازه ­های زمانی پس از پاشش قارچ روی میزبان، یک روند کاهشی روی نرخ ذاتی افزایش جمعیت زنبور ایجاد شد. نرخ خالص تولید مثل (R0)، نرخ ناخالص تولید مثل (GRR)، زمان لازم برای رشد یک نسل (T) و نرخ متناهی رشد (λ) پارازیتوئید روی میزبان سالم به ترتیب 75/41 نتاج ماده، 42/43 نتاج ماده، 32/18 روز و 22/1 بر روز برآورد شد که اختلاف معنی­ داری را با بازه­ های زمانی پس از آلودگی قارچی میزبان نشان ­داد و بیانگر این نکته بود که توان تولیدمثلی زنبور پارازیتوئید روی میزبان ­های آلوده به قارچ در مقایسه با میزبان­های سالم کاهش می­ یابد.

The side-effects of amitraz, buprofezin and propargite were studied on Encarsia formosa (Gahan)in the laboratory, using a life table response experiment and the IOBC system for their toxicity. Bioassayswere conducted by dipping bean leaves containing third instar nymphs of the whitefly Trialeurodesvaporariorum (Westwood), parasitized by E. formosa, in insecticide solutions or caging adult parasitoidsin treated petri dishes. The insecticide buprofezin caused 19.87% and 11.87% mortality in adults andpupae respectively. Amitraz showed the highest level of toxicity for the adults (100% mortality) and thepupae of parasitoids (83.3% mortality). Both buprofezin and propargite caused no adverse effect on thefecundity and longevity of parasitoids, but amitraz significantly reduced the fecundity and longevity ofadults. Life table assay indicated that buprofezin and propargite have no major impact on the intrinsic rateof natural increase (rm), while amitraz lowered the rm value by 7.03%. According to the IOBCclassification of toxicity, buprofezin was found to be harmless for the pupae and adults and amitrazproved to be harmful for adults. Based on both the life table and IOBC methodology, buprofezin andpropargite are found to be relatively safe for E. formosa and can be used in integrated pest managementprograms where this parasitoid is involved.

The whitefly Bemisia tabaci (Gennadius) is a globally distributed species complex that includes several destructive pests of agriculture. In recent years, the high ability of B. tabaci to develop insecticide resistance indicates that using insecticides to control this pest has become unsustainable. Use of natural enemies as part of integrated management approaches is considered a key strategy for long term sustainable control. Here we investigated the effects of host species on the performance of a parasitoid. We tested this using Encarsia formosa Gahan (Hymenoptera Aphelinidae) and two members from B. tabaci species complex, MEAM1 and AsiaII7. The parasitoids were reared using MEAM1 or AsiaII7 hosts feeding on hibiscus. Those maintained on MEAM1 are referred to as M-E. formosa and those on AsiaII7 as A-E. formosa. Results showed that there were no significant differences between the pre-imaginal developmental times of M-E. formosa and A-E. formosa regardless of their whitefly hosts. However, M-E. formosa emergence rate after parasitism on MEAM1 was higher than that of A-E. formosa parasitizing MEAM1. On the contrary, A-E. formosa emergence rate after parasitism on AsiaII7 was higher than that observed for M-E. formosa parasitizing AsiaII7. In no-choice experiments, M-E. formosa females parasitized MEAM1 and AsiaII7 hosts in a similar rate but A-E. formosa parasitized less MEAM1 than AsiaII7 hosts. In choice experiments, M-E. formosa females parasitized more MEAM1 than AsiaII7 hosts and A-E. formosa parasitized AsiaII7 and MEAM1 hosts equally. These parasitism rates mirrored for the host checking and oviposition behavior of different E. formosa strains. Our results indicate that B. tabaci species does not influence parasitoid development period until adulthood, but that pre-imaginal experience is important for emergence rate, parasitism rate and behavior of E. formosa adults. [ABSTRACT FROM AUTHOR]

The host preference in Encarsia formosa was studied when parasitoid receiving signals related to either untreated and Lecanicillium longisporum-treated Trialeurodes vaporariorum . The experiments were done by the type two selection experiment. The third instar nymphs of T. vaporariorum were used as parasitoid host. Untreated hosts sprayed with Tween 80 as control and treated host infected by the three isolates of L. longisporum ; LRC190, LRC216 and LRC229. Simultaneously, the healthy hosts were presented to parasitoid with the infected hosts at four time intervals: 0, 24, 48 and 72 h post-treatment. This investigation showed a highly significant preference of E. formosa towards the untreated host at 24, 48 and 72 h after fungi spraying. Whereas in 0 h after fungi treatment parasitoids could not discriminate between healthy and infected host therefore, there was not a preference to host selection. The highest Manly's preference index (β) of parasitoid to choose healthy hosts in the simultaneous presence of infected hosts by isolates LRC190, LRC216 and LRC229 was estimated 0.88 ± 0.02, 0.87 ± 0.02 and 0.79 ± 0.03, respectively at 72 h after spraying, while the lowest value was estimated 0.44 ± 0.03, 0.49 ± 0.4 and 0.52 ± 0.03, respectively, at 0 h after treatment. Overall we concluded that female parasitoid is capable recognize infected host in longer time intervals after treatment and prefers to lay on the uninfected ones. These results demonstrated the suitable adaptation of simultaneous application of E. formosa and L. longisporum for biological control of T. vaporariorum . [ABSTRACT FROM AUTHOR]

The beneficial effects of direct predation by zoophytophagous biological control agents (BCAs), such as the mirid bug Nesidiocoris tenuis, are well-known. However, the benefits of zoophytophagous BCAs' relation with host plants, via induction of plant defensive responses, have not been investigated until recently. To date, only the females of certain zoophytophagous BCAs have been demonstrated to induce defensive plant responses in tomato plants. The aim of this work was to determine whether nymphs, adult females, and adult males of N. tenuis are able to induce defense responses in tomato plants. Compared to undamaged tomato plants (i.e., not exposed to the mirid), plants on which young or mature nymphs, or adult males or females of N. tenuis fed and developed were less attractive to the whitefly Bemisia tabaci, but were more attractive to the parasitoid Encarsia formosa. Female-exposed plants were more repellent to B. tabaci and more attractive to E. formosa than were male-exposed plants. When comparing young- and mature-nymph-exposed plants, the same level of repellence was obtained for B. tabaci, but mature-nymph-exposed plants were more attractive to E. formosa. The repellent effect is attributed to the signaling pathway of abscisic acid, which is upregulated in N. tenuis-exposed plants, whereas the parasitoid attraction was attributed to the activation of the jasmonic acid signaling pathway. Our results demonstrate that all motile stages of N. tenuis can trigger defensive responses in tomato plants, although these responses may be slightly different depending on the stage considered. [ABSTRACT FROM AUTHOR]