Basis and monitoring of methoxyfenozide resistance in the South American tomato pinworm Tuta absoluta

The South American tomato pinworm, Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae), is heavily targeted by insecticide applications. Methoxyfenozide is highly effective against T. absoluta with reduced side effects to natural enemies. This work aimed to (1) genetically and biochemically characterize resistance of the T. absoluta GBN population to methoxyfenozide, (2) establish cross resistance profiles with other insecticide groups and (3) monitor resistance in populations with the goal of improving T. absoluta insecticide resistance management (IRM). Methoxyfenozide resistance was completely recessive, polyfactorial and autosomal. Effective dominance revealed that 10 mg methoxyfenozide/L would be enough to eliminate susceptible homozygotes and heterozygotes, thus used to diagnose resistance in field populations. The synergism of methoxyfenozide toxicity in the resistant population for PBO (SR?=?95×), DEF (SR?=?51×) and DEM (SR?=?45×), suggested monooxygenases, esterases and glutathione S-transferases as resistance mechanisms. However, only monooxygenase activity appeared to be involved in methoxyfenozide resistance. Resistance ratio for methoxyfenozide (2352-fold) after selection and cross-resistance ratios of a lab-selected GBN strain (“GBN-Sel”) were significant relative to a susceptible strain “JDR1-Sus” for tebufenozide (656-fold), cartap hydrochloride (10.68-fold), deltamethrin (4.70-fold), abamectin (2.65-fold), lufenuron (2.22-fold) and indoxacarb (1.92-fold), with negative cross-resistance to spinetoram (0.32-fold). Evidence of control failures was observed in 10 field populations of T. absoluta (mortalities between 13 and 76%), and all populations showed frequencies of resistant phenotypes (percentage survivorship ranging between 4 and 96%). A rational basis for managing resistance to bisacylhydrazines is discussed, along with details of recommended T. absoluta resistance management tactics.

     

First report of Tuta absoluta resistance to diamide insecticides

Journal of Pest Science - The tomato borer Tuta absoluta (Lepidoptera: Gelechiidae) is an invasive pest of tomato crops that is rapidly expanding around the world. It is considered a devastating...     

First evidence of deuterotokous parthenogenesis in the tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

The tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae), originates from South America and is now considered to be one of the most damaging invasive pests of tomatoes in the Mediterranean Basin countries of Europe and North Africa. The preventing pest mating control methods include: (1) the use of synthetic pheromones for male attraction and annihilation inside insecticide-containing traps; (2) mating disruption by saturating the atmosphere with sex pheromones which alter the ability of males to locate females; and (3) massive applications of sterile males to alter the overall reproductive success of the pest population. However, all these methods achieve only a poor success rate in controlling T. absoluta populations under greenhouse conditions. Sex pheromone management and sterile insect techniques are both based on an important biological trait: the insect must breed through sexual reproduction. Here, we report for the first time laboratory evidence of deuterotokous parthenogenesis, an asexual reproduction where both males and females are produced from unfertilized eggs. We discuss the consequences for T. absoluta control strategies.     

Biological invasion of European tomato crops by Tuta absoluta: ecology, geographic expansion and prospects for biological control

The tomato leafminer Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is a devastating pest of tomato originating from South America. After its initial detection in eastern Spain in 2006, it rapidly invaded various other European countries and spread throughout the Mediterranean basin. If no control measures are taken, then the pest can cause up to 80–100% yield losses in tomato crops in recently invaded areas and may pose a threat to both greenhouse and open-field tomato production. The exceptional speed and extent of T. absoluta invasion have called for studies documenting its biology and ecology, while indicating an urgent need for efficient and sustainable management methods. The development of approaches to manage T. absoluta would be facilitated through a detailed revision of information on this pest in its area of origin. This review combines information on the invasion by T. absoluta, its ecology, and potential management strategies, including data that may help the implementation of efficient biological control programs. These programs, together with a variety of other management tactics, may allow efficient integrated pest management of T. absoluta in Europe and Mediterranean Basin countries.     

Biology of two key Palaearctic larval ectoparasitoids when parasitizing the invasive pest Tuta absoluta

During the last few years following the invasion of European tomato crops by the invasive South American tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), several indigenous larval parasitoid species were recorded as natural enemies of this pest. Necremnus cf. artynes (Walker) and to a lesser extent Stenomesius sp. nr. japonicus (Ashmead) (Hymenoptera: Eulophidae) have been frequently reported attacking T. absoluta in tomato greenhouses in Europe and they are considered as possible biocontrol agents. Few biological data are available on these two species, notably when they parasitize T. absoluta. Therefore, the present study documents their biology when parasitizing T. absoluta, and provides scientific bases for potential development of biological control programs relying on larval ectoparasitoids in invaded areas. We demonstrated the ability of the two parasitoid species to reproduce on T. absoluta as host on tomato plants. On average, N. cf. artynes female parasitized 28.5 larvae and killed 26.2 larvae during its life time whereas S. sp. nr. japonicus female was more long-lived and consequently more efficient; it parasitized 144.3 larvae and killed 90.1 larvae. In a second step, we also explored the effect of T. absoluta larvae instar on parasitism by S. sp. nr. japonicus and subsequent development of the parasitoid offspring. Best results were obtained with the third larvae instar with a higher number of offspring produced, bigger individuals and a higher proportion of females. Our results support the hypothesis that the two species are good candidates for biological control programs targeting T. absoluta in Europe.     

甲维盐混配剂诱木注药防治松褐天牛研究

研究甲维盐混配剂对马尾松的安全性、马尾松吸收药液情况、混配剂在马尾松树体内作用的持效期以及混配剂的剂量,结果表明:1)对胸径8 cm以上马尾松注干输药时,安全性高,达95%以上;2)对马尾松注干输药时,马尾松在各个时间均有良好的吸收率,达96%以上;3)甲维盐混配剂在马尾松树体内持效期长,可达5个月;4)使用5%甲维盐混配剂100 mL防治松褐天牛效果最佳,达到99.83%.     

Oak mortality associated with crown dieback and oak borer attack in the Ozark Highlands

Oak decline and related mortality have periodically plagued upland oak–hickory forests, particularly oak species in the red oak group, across the Ozark Highlands of Missouri, Arkansas and Oklahoma since the late 1970s. Advanced tree age and periodic drought, as well as Armillaria root fungi and oak borer attack are believed to contribute to oak decline and mortality. Declining trees first show foliage wilt and browning, followed by progressive branch dieback in the middle and/or upper crown. Many trees eventually die if severe crown dieback continues. In 2002, more than 4000 living oak trees ≥11 cm dbh in the relatively undisturbed mature oak forests of the Missouri Ozark Forest Ecosystem Project (MOFEP) were randomly selected and inventoried for tree species, dbh, crown class, crown width, crown dieback condition (healthy: <5% crown dieback, slight: >5–33%, moderate: 33–66%, and severe: >66%) and number of emergence holes created by oak borers on the lower 2.4 m of the tree bole. The same trees were remeasured in 2006 to determine their status (live or dead). In 2002, about 10% of the red oak trees showed moderate or severe crown dieback; this was twice the percentage observed for white oak species. Over 70% of trees in the red oak group had evidence of oak borer damage compared to 35% of trees in the white oak group. There was significant positive correlation between crown dieback and the number of borer emergence holes (p < 0.01). Logistic regression showed oak mortality was mainly related to crown width and dieback, and failed to detect any significant link with the number of oak borer emergence holes. Declining red oak group trees had higher mortality (3 or 4 times) than white oaks. The odds ratios of mortality of slightly, moderately, and severely declining trees versus healthy trees were, respectively, 2.0, 6.5, and 29.7 for black oak; 1.8, 3.8, and 8.3 for scarlet oak; and 2.6, 6.5 and 7.1 for white oaks.     

Natural enemies of the South American moth, Tuta absoluta, in Europe, North Africa and Middle East, and their potential use in pest control strategies

The South American tomato leafminer, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), is an invasive Neotropical pest. After its first detection in Europe, it rapidly invaded more than 30 Western Palaearctic countries becoming a serious agricultural threat to tomato production in both protected and open-field crops. Among the pest control tactics against exotic pests, biological control using indigenous natural enemies is one of the most promising. Here, available data on the Afro-Eurasian natural enemies of T. absoluta are compiled. Then, their potential for inclusion in sustainable pest control packages is discussed providing relevant examples. Collections were conducted in 12 countries, both in open-field and protected susceptible crops, as well as in wild flora and/or using infested sentinel plants. More than 70 arthropod species, 20 % predators and 80 % parasitoids, were recorded attacking the new pest so far. Among the recovered indigenous natural enemies, only few parasitoid species, namely, some eulophid and braconid wasps, and especially mirid predators, have promising potential to be included in effective and environmentally friendly management strategies for the pest in the newly invaded areas. Finally, a brief outlook of the future research and applications of indigenous T. absoluta biological control agents are provided.     

Gene introgression in assessing fitness costs associated with phosphine resistance in the rusty grain beetle

Journal of Pest Science - The current study investigates the fitness cost associated with phosphine resistance in the rusty grain beetle, Cryptolestes ferrugineus (Stephens), a problematic pest in...     

纵坑切梢小蠹伴生菌--云南半帚孢毒素作用机理的初步研究

用纵坑切梢小蠹伴生菌——云南半帚孢Laeptographium yunnanense的毒素处理后，云南松和华山松体内与抗病性密切相关的过氧化物酶、多酚氧化酶和苯丙氨酸解氨酶的活性都明显地下降，表明该毒素可以通过抑制寄主体内与抗性有关的酶的活性来削弱寄主的抗性，从而有利于菌在寄主体内侵染生长。云南松的酶活性下降的程度较大，而华山松的酶活性较高，毒素处理后活性受抑制的程度相对较小，这表明华山松对云南半帚孢的抗御能力较云南松的强，这也是云南境内云南松受害严重而华山松受害轻微的重要原因之一。     

纵坑切梢小蠹伴生菌危害机理的研究

该文对纵坑切梢小蠹伴生菌Leptographium yunnanense的危害机理作了初步研究,结果表明,L.yunnanense在与小伴随侵入后,产生致病毒素对寄主树林进行危害,从而辅助纵坑切梢小蠹成功定殖于寄主树木内,该毒素在低浓度条件下仍维持一定的致病力,进一步表明伴生菌在小蠹虫成功蛀害的过程中具有重要的作用。     

There is more than chitin synthase in insect resistance to benzoylureas: molecular markers associated with teflubenzuron resistance in Spodoptera frugiperda

Journal of Pest Science - Chitin synthesis inhibitors are successfully used in pest control and an excellent option for integrated pest management programs due to their low non-target effects....     

Identification of some compounds associated with resistance of Pinus densiflora to Fomes annosus

From the heartwood-free stemwood of Pinus densiflora, 7 compounds inhibitory to the linear growth of Fomes annosus were isolated. These were identified as pinosylvin, pinosylvin monomethyl ether, (3-sitosterol, a cembrol-like diterpene alcohol, and three isomeric diterpene acids belonging to the abietane group, one of which is probably palustric acid. Other antifungal fractions contained complex mixtures and were not characterized.     

Mutations associated with pyrethroid resistance in the honey bee parasite Varroa destructor evolved as a series of parallel and sequential events

Journal of Pest Science - Managed honey bees have suffered severe seasonal losses for most of the past 30&nbsp;years, while at the same time there is a growing need for food crop pollination....     

Estimating the frequency of stem rot in Picea abies using an increment borer

The likelihood of detecting decay present in Norway spruce trees when taking bore core samples at breast height or at stump height was analyzed in two stands. The actual numbers of decayed trees were obtained after the trees were felled. More than 80% of the decay extending to breast height level was detected by taking core samples at that level. However, these core samples revealed only 40–70% of the actual amount of decay present at stump height. At stump height a higher portion of the total amount of decay present was revealed. Heterobasidion annosum was detected in 69 and 77% of the decayed trees in the two stands.

Misjudgements occurred mainly where either (i) decay was present at stump height but not at breast height or (ii) when the decay column had a lateral position. At breast height the probability of finding lateral rot columns was higher than at stump height.     

Biochemical responses associated with induced resistance to Colletotrichum acutatum in Pinus radiata seedlings treated with methyl jasmonate and Trichoderma spp.

The effect of Trichoderma (T. atrobrunneumFCC320 and T. atrovirideLU633) and/or methyl jasmonate (MJ) on resistance to terminal crook (Colletotrichum acutatum) and on seedling biochemistry was investigated in radiata pine (Pinus radiata) seedlings. Seedlings were germinated and grown in Trichoderma‐amended or non‐amended media for 3 months and then sprayed with 2.25 mM MJ 1 week before inoculation with C. acutatum. The incidence and severity of terminal crook in the seedlings treated with MJ and Trichoderma+MJ were lower than in Trichoderma‐treated and Trichoderma‐untreated seedlings. The MJ‐induced resistance response was concomitant with an increase in the concentrations of the monoterpenes α‐pinene, β‐pinene, β‐phellandrene, camphene and myrcene in needles, and also α‐pinene, β‐pinene and camphene in stems. The concentrations of α‐pinene, β‐pinene and camphene were elevated from at least 1 week until 4 weeks after MJ application, compared with those in non‐MJ counterparts. Trichoderma alone did not affect monoterpenes, but the concentrations of α‐pinene, β‐pinene and camphene were greater in needles of Trichoderma+MJ than in MJ‐treated seedlings after 28 days. Total phenolic concentration in needles and peroxidase activity in stems were twofold greater in MJ‐treated seedlings than in non‐MJ seedlings over the same period. None of the treatments affected the activity of peroxidase in needles. It is proposed that the accumulation of monoterpene and phenolics and the induction of peroxidases contribute, in part, to MJ‐induced resistance to terminal crook in radiata pine seedlings.