Few indirect effects of baculovirus on parasitoids demonstrate high compatibility of biocontrol methods against Tuta absoluta

BACKGROUND

Combining different biocontrol agents, particularly micro- and macroorganisms, can contribute to new and sustainable pest control approaches. Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is one of the most destructive pests of solanaceous crops. An emerging management strategy consists of biological control using microbial insecticides such as baculoviruses, but with limited efficacy. Thanks to their high target specificity, baculoviruses can be used simultaneously with natural enemies such as parasitoids for improved control of T. absoluta. However, potential indirect nontarget effects of baculoviruses on parasitoids can result from overlapping resource requirements. We assessed whether ovipositing parasitoid females discriminated against virus-treated hosts and examined the outcome of within-host competition between the hymenopteran parasitoids Necremnus tutae (Reuter) (Eulophidae) and Dolichogenidea gelechiidivoris Marsch (Braconidae), and the Phthorimaea operculella granulovirus (PhopGV, Baculoviridae) that infects T. absoluta larvae.

RESULTS

Female D. gelechiidivoris discriminated against virus-treated hosts, whereas N. tutae did not. We found few indirect virus-related effects depending on the species, the sex, and the time of virus treatment. Effects were ambivalent for D. gelechiidivoris offspring and ranged from increased male longevity when infection occurred before parasitization to reduced emergence and male longevity when infection occurred after parasitization. N. tutae offspring showed a longer development time and shorter male longevity when they developed in virus-treated hosts.

CONCLUSION

The virus had a low impact on parasitoid offspring. In rare cases, adverse effects were detected; however, the low magnitude of these effects is unlikely to reduce the fitness of parasitoid offspring, therefore both parasitoids seem compatible with the baculovirus for control of T. absoluta. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

The tomato leafminer Tuta absoluta (Meyrick) in Tunisia: current status and management strategies

The tomato leafminer Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) was first identified in the region of Akkouda in October 2008 before it spread to all tomato‐producing areas in Tunisia. The introduction of this pest disturbed existing pest control programmes in greenhouses and open fields, forcing Tunisian growers to use more chemicals to reduce its impact on their crops. A national programme was adopted to control T. absoluta, including cultural practices, the use of pheromones, the installation of insect‐proof screens in greenhouses, and the use of organic insecticides including Bacillus thuringiensis Kurstaki (Bt) and plant extract‐based products. In addition, a few experiments in biological control, using the predatory Mirid Nesidiocoris tenuis Reuter (Heteroptera: Miridae) and the parasitoid wasp Trichogramma cacoeciae Marchal (Hymenoptera: Trichogrammatidae), were conducted in greenhouses and open‐field crops (producing tomatoes for fresh consumption as well as for processing). This paper describes the status of T. absoluta in Tunisia, including data collected from sex pheromone traps installed in six tomato‐producing areas (Takelssa, Korba, Teboulba, Bekalta, Sousse and Kairouan) between 2009 and 2011, and control strategies in greenhouses and open fields.     

Bioactivity of compounds from Acmella oleracea against Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) and selectivity to two non-target species

BACKGROUND: Tropical plants are recognised sources of bioactive compounds that can be used for pest control. The objective of this study was to evaluate the biological activity of compounds present in Acmella oleracea (Asteracea) against Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), which is the main pest of tomato crops in Latin America. The selectivity of these compounds to the predator Solenopsis saevissima (Smith) (Hymenoptera: Formicidae) and to the pollinator Tetragonisca angustula (Latr.) (Hymenoptera: Apidae: Meliponinae) was also of interest. RESULTS: A bioassay screening with hexane and ethanol extracts from 23 plants was performed. The hexane extract of A. oleraceae was the most active of the extracts and was selected for further study. The following three alkamides were isolated from a hexane extract of the aerial parts of A. oleracea : spilanthol, (E)‐N‐isobutylundeca‐2‐en‐8,10‐diynamide and (R, E)‐N‐(2‐methylbutyl)undeca‐2‐en‐8,10‐diynamide. All of the isolated compounds showed insecticidal activity, with spilanthol being the most active (LD₅₀ = 0.13 µg mg^?1) against T. absoluta . The alkamides were selective to both beneficial species studied. CONCLUSION: The crude hexane extract of A. oleraceae showed high insecticidal activity and can be used to control T. absoluta in organic or conventional crops. Quantification of LD₅₀ values of isolated compounds against T. absoluta showed that alkamides could serve as potent insecticides for T. absoluta control programmes. Spilanthol was the main alkamide active isolated. This alkamide is the most promising as it has the highest insecticidal activity and is selective to non‐target organisms. Copyright © 2011 Society of Chemical Industry     

Experimental studies on Tuta absoluta (Meyrick) in protected tomato crops in France: biological control and integrated crop protection

Tuta absoluta is a pest from South America which has been detected in many European and Mediterranean countries since 2006. It was identified in Corsica and the South of France in late 2008, and by 2010 this Lepidopteran species had spread to further tomato‐production areas. The pest is present mainly on tomatoes in protected and field crops, and damage on leaves and fruit can be so severe that it can lead to total destruction of the plant. Since 2010, studies have been carried out in experimental insect‐proof glasshouses with artificial infestations of the pest. The objective was to gain better knowledge of this emergent pest and to develop adapted control strategies under the conditions of the South‐East of France. Integrated pest management is widely used on tomato crops in France, and the predator Macrolophus pygmaeus and the parasitoid Trichogramma achaeae were studied, alone and in combination. The possible effect of the concurrent prey Trialeurodes vaporariorum on the impact of the predator on T. absoluta was also studied. The best results were obtained when the two beneficials were released in combination, even in the presence of whiteflies T. vaporariorum.     

Comparative study of 2 protection strategies against Tuta absoluta (Meyrick) in late open field tomato crops in Tunisia

A comparative study of 2 protection strategies against Tuta absoluta (Meyrick) in open field tomato crops was performed. The first strategy used Integrated Pest Management (IPM) through mass trapping, release of Nesidiocoris tenuis and rational use of compatible insecticides. The second strategy was based on conventional use of synthetic insecticides (9 treatments). This study revealed at the end of the culture a 20% infestation rate of leaves in the IPM cropping system versus 98% in the conventional cropping system. The infestation rate of fruit was 18.2% in the IPM cropping system versus 46.8% with the conventional one.     

Evaluation of two methods for the protection of tomato crops against the tomato leafminer Tuta absoluta (Meyrick) under greenhouses in Tunisia

The evaluation of two methods of plant protection in tomato crops cultivated in greenhouses against Tuta absoluta (Meyrick) in the region of Teboulba in Tunisia was performed. This study evaluated the use of insect‐proof screens alone or in combination with one sex pheromone water trap compared to a control greenhouse not equipped with either. The study confirms that the use of one sex pheromone water trap combined with insect‐proof covering of doors and aeration openings is sufficient to guarantee good crop protection. This combined control system allowed a low density of the pest (less than 2 individuals per leaf) to be maintained and a mean number of mines below 1 mine per leaf.     

人工卵赤眼蜂对玉米害虫的控害效果

研究表明,用人工卵繁殖的松毛虫赤眼蜂和螟黄赤眼蜂对夏玉米田２～３代玉米螟均有较好的控害效果。放蜂区校正卵粒寄生率为６５．４４％～６８．１６％;百株玉米蛀孔数和雄穗被害较对照分别减少６６．６７％～７０．３７％和７３．３３％～８０．００％。防治玉米雌穗上棉铃虫的效果,螟黄赤眼蜂要明显好于松毛虫赤眼蜂（２０．０％）,虫口减退率达７１．１％。另外还研制了适合人工卵赤眼蜂田间放蜂的放蜂器,出蜂率达９０％以上。     

设施番茄4种栽培方式下番茄潜叶蛾对化蛹场所的选择性研究

为提高番茄潜叶蛾的监测与防控效率,在樱桃番茄生产温棚开展了双色地膜土栽、地砖托盘盆栽、地砖盆栽、地布盆栽4种栽培方式下番茄潜叶蛾对化蛹场所的选择性研究。依据栽培方式,调查了12种可能的化蛹场所。结果表明,番茄的栽培方式不同,番茄潜叶蛾的化蛹场所亦有明显变化。双色地膜土栽方式下,6种场所的总计平均化蛹数量和化蛹数量占比中,地膜覆盖土显著高于其他场所,依次为地膜覆盖土>种植孔周边和茎秆>叶片;叶柄和果实上未观察到有幼虫化蛹。地砖托盘盆栽方式下,9种场所的总计平均化蛹数量中,花盆托盘底部和花盆翻边显著多于花盆盆底,其他场所未观察到有幼虫化蛹;化蛹数量占比中,花盆托盘底部显著高于其他场所,依次为花盆托盘底部>花盆翻边>花盆盆底。地砖盆栽方式下,8种场所的总计平均化蛹数量中,地砖缝隙和花盆翻边显著多于花盆盆底,其他场所未观察到有幼虫化蛹;化蛹数量占比中,地砖缝隙显著高于花盆翻边和花盆盆底。地布盆栽方式下,8种场所的总计平均化蛹数量和化蛹数量占比中,花盆盆底显著高于其他场所,依次为花盆盆底>花盆翻边>地布表面,其他场所未观察到幼虫化蛹。双色地膜土栽方式下4种化蛹...     

Two new species of egg parasitoids (hymenoptera: Encyrtidae) of wood-boring beetle pests from China

Oobius agrili sp.n. andAvetianella xystrocerae sp.n. (Hymenoptera: Encyrtidae) are described from China. Morphological characters of the new species are illustrated.O. agrili is an egg parasitoid of the emerald ash borerAgrilus planipennis Fairmaire (Coleoptera: Buprestidae) andA. xystrocerae is an egg parasitoid of the wood borerXystrocera globosa (Olivier) (Coleoptera: Cerambycidae). The two new species are potential biocontrol agents of economically important pest insects. The type specimens are deposited in the Institute of Zoology, Chinese Academy of Sciences, Beijing (IZCAS). http://www.phytoparasitica.org posting May 17, 2005.     

Bioresidual and integrated pest management status of a biorational agent and a novel insecticide against whitefly and its key parasitoids

The effects of continuous exposure of the adult and crawler stages of the whitefly, Trialeurodes vaporariorum, and adult of the parasitoids Encarsia formosa and Eretmocerus eremicus to spray deposits of potassium salts of a fatty acid and diafenthiuron applied at recommended rates were evaluated. French bean, Phaseolus vulgaris Prince, plants were sprayed and the adults confined on them using modified 5 cm Petri dishes. Fresh (4 - 5-h-old) deposits of fatty acids resulted in a 10.7% mortality rate of whitefly adults and 8.0 and 10.7% mortality rates of E. formosa and E. eremicus adults respectively, while fresh deposits of diafenthiuron resulted in a 62.7% mortality rate of whitefly adults and 12.0 and 14.7% mortality rates of E. formosa and E. eremicus respectively. The mortality rate (6.9 and 69.7%) of whitefly crawlers was recorded when exposed to 24-h-old deposits of fatty acids and diafenthiuron respectively. The mortality rate declined as the deposits aged. Adult parasitoid emergence from the treated pupae was unaffected. Spray deposits of diafenthiuron were effective against whitefly for up to 2-3 weeks in comparison with fatty acids, which were effective only when sprayed. Both products were harmless to adults as well as pupae of both parasitoids irrespective of the exposure period (age of deposits) tested (IOBC Class 1). These insecticides can be included in integrated pest management strategies against whitefly with the fatty acids used on horticultural crops.     

Studies on the development of a mating disruption system to control the tomato leafminer, Tuta absoluta Povolny (Lepidoptera: Gelechiidae)

BACKGROUND: The tomato leafminer (Tuta absoluta Povolny) has rapidly colonised the whole Mediterranean and South‐Atlantic coasts of Spain, and it has become a key problem in both outdoor and greenhouse crops. New control methods compatible with biological control are required, and mating disruption appears to be a perfect method in current agriculture, as it is an environmentally friendly and residue‐free technique. IPM packages tested have included the use of pheromones to detect populations, but there has not been much previous research on mating disruption of T. absoluta. In this work, pheromone doses varying from 10 to 40 g ha^?1, emitted at a constant rate over 4 months, were tested in greenhouses with different levels of containment in order to evaluate the efficacy of mating disruption on T. absoluta. RESULTS: Trials on containment level revealed that the flight of T. absoluta was satisfactorily disrupted with an initial pheromone dose of 30 g ha^?1, and levels of damage did not significantly differ from those in reference plots with insecticide treatments. Later efficacy trials confirmed previous experiences, and release studies showed that control of damage and flight disruption were taking place when releasing at least 85 mg pheromone per ha per day. CONCLUSION: Effective control using pheromone application against T. absoluta can be achieved, in greenhouses with high containment levels, for 4 months, with initial doses of 30 g ha^?1. Further research must be conducted in order to evaluate the prospect of outdoor application of mating disruption systems. Copyright © 2011 Society of Chemical Industry     

Determination of baseline susceptibility of European populations of Tuta absoluta (Meyrick) to indoxacarb and chlorantraniliprole using a novel dip bioassay method

BACKGROUND: Tuta absoluta(Meyrick) is one of the most serious pests of tomato recently introduced in the Mediterranean region. A novel bioassay method designed for the accurate determination of insecticide toxicity on T. absoluta (IRAC method No. 022) was validated by three different laboratories [Greece (NAGREF), Italy (UC) and Spain (UPCT)] on European populations. RESULTS: The insecticides indoxacarb and chlorantraniliprole were used as reference products. The IRAC leaf dip method is easy to perform, producing repeatable, homogeneous responses. LC₅₀ values for indoxacarb ranged between 1.8 and 17.9 mg L^?1 (NAGREF), 0.93 and 10.8 mg L^?1 (UC) and 0.20 and 0.70 mg L^?1 (UPCT), resulting in a tenfold, 12‐fold and fourfold difference between the least and most susceptible populations at each laboratory respectively. For chlorantraniliprole, LC₅₀ values ranged between 0.10 and 0.56 mg L^?1 (NAGREF), 0.23 and 1.34 mg L^?1 (UC) and 0.04 and 0.24 mg L^?1 (UPCT), resulting in a sixfold difference in all three cases. Overall, UPCT reported lower mean LC₅₀ to indoxacarb, while UC reported higher LC₅₀ to chlorantraniliprole. CONCLUSIONS: The new bioassay is reliable, providing a useful tool in the design of IRM strategies. Within each country/lab, the variability observed in the results for both indoxacarb and chlorantraniliprole can be attributed to natural variation. Future research is necessary to determine the extent to which it is possible to compare results among laboratories. Copyright © 2012 Society of Chemical Industry     

Susceptibility of tomato borer,Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) populations from Turkey to 7 different insecticides in laboratory bioassay

The tomato borer, Tuta absoluta (Meyrick), was first recorded in Turkey in August 2009 and rapidly became a serious pest in the Mediterranean and Aegean coastal regions in field and greenhouse grown tomatoes. Currently, insecticides are considered one of the major tools for the management of T. absoluta in Turkey. This study, investigated the efficacy of 7 different insecticides, against T. absoluta in laboratory bioassays. To determine the lethal concentration (LC) values and feeding activity of the larvae, tomato leaf parts mined by 1–3 day old L1 larvae were dipped into different insecticide concentrations. Mortality was recorded 5 days after insecticide treatments. Spinosad, chlorantraniliprole + abamectin or indoxacarb treatment resulted in 100% mortality with minimal or no feeding in all populations at their recommended doses of 120, 50.4 and 60 mg a.s. L^?1, respectively. In general, the LC₉₉ values of populations for these insecticides were similar and also lower than that of the recommended field doses. The effect of pyridalyl was low, resulting in low mortality with serious feeding damage at the dose of 125 mg a.s. L^?1. The efficacies of abamectin, metaflumizone and azadirachtin were found to be moderate to low at the recommended doses (4.5, 240 and 50 mg a.s. L^?1, respectively). However, these insecticides may affect pupation and adult emergence rates hence further studies are recommended to investigate these insecticides.     

Response of the tomato miner Tuta absoluta (Lepidoptera: Gelechiidae) to thirteen insecticides in semi‐natural conditions in Tunisia

Experiments on larvicide and ovicide activity of 13 insecticides in semi‐natural conditions showed a medium to low efficacy of bio‐insecticides on all instars of Tuta absoluta (Meyrick) except for Bacillus thuringiensis Berliner var. kurstaki which was distinguished by an average mortality of 72.5%. Spinosad and Spinetoram based insecticides showed high efficiency in controlling all instars of larvae with respectively an average mortality of 66.5% and 85.6%. However, this study revealed a unique ovicide effect of azadirachtin‐neem oil based insecticide with 43.8% egg mortality.     

Comparative effect of integrated pest management and farmers' standard pest control practice for managing insect pests on cabbage (Brassica spp.)

BACKGROUND: Studies were conducted on experimental cabbage plantings in 2009 and on experimental and commercial plantings in 2010, comparing farmers' current chemical standard pesticide practices with an integrated pest management (IPM) program based on the use of neem (Aza‐Direct) and DiPel (Bacillus thuringiensis). In experimental plantings, the IPM program used six or eight applications of neem and DiPel on a rotational basis. The standard‐practice treatments consisted of six or eight applications of carbaryl and malathion or control treatment. RESULTS: The IPM treatments reduced pest populations and damage, resulting in a better yield than with the standard chemical or control treatment. When IPM treatment included three applications of neem plus three applications of DiPel (on a rotational basis in experimental fields), it again reduced the pest population and damage and produced a better yield than the standard practice. The lower input costs of the IPM program resulted in better economic returns in both trials. CONCLUSIONS: The IPM components neem and DiPel are suitable for use in an IPM program for managing insect pests on cabbage (Brassica spp.). Copyright © 2011 Society of Chemical Industry