Sterilisation of the potato moth, Phthorimaea operculella (Lepidoptera: Gelechiidae) by fumigation with thiotepa

The chemosterilant thiotepa was used in fumigation chambers for sterilisation of male and female potato moths. Its effectiveness was registered by recording egg production, egg hatch, longevity of moths, and mating frequency. Also studied was the effect on the persistence of the chemical of temperature, exposure time and concentration. The tests showed that it was possible to sterilise fully male and female moths with thiotepa without adverse effects on mating and longevity. Generally, males were more susceptible to sterilisation than females. No definite relationship was found between dosage and egg production, longevity and mating frequency of moths. The compound did not lose its sterilising activity when used successively up to five times during the same day or once weekly for a total of 4 wk. The sterilising activity was related to temperature, exposure time, concentration and rates of airflow of the circulatory fumigation chambers. Some reduction of fertility occurred when F, adults paired with untreated moths.     

马铃薯块茎蛾生物学、生态学与综合治理

马铃薯块茎蛾又称烟草潜叶蛾Phthorimaea operculella,起源于中美洲和南美洲北部地区,现已分布在亚洲、欧洲、北美洲、非洲等100多个国家,是茄科作物的世界性农业害虫,尤其对马铃薯有毁灭性的危害。目前,该虫在我国南方马铃薯产区普遍发生,尤其是在云南、四川、贵州等地区该害虫发生极为严重,且随着气候的变化该虫可能会扩散到其他马铃薯生产区。马铃薯块茎蛾主要进行两性生殖,少数孤雌生殖,其幼虫钻蛀叶片和薯块危害。初孵幼虫无性二态性,4龄幼虫、蛹和成虫均可依据外形特征进行雌雄区分。马铃薯块茎蛾发生世代数取决于当地的农业气候条件,年发生2~12代。马铃薯块茎蛾对温度有广泛的适应性,且在干燥炎热的年份该虫容易大爆发。马铃薯块茎蛾早期防控主要集中在种植抗性品种、深种、灌溉等农业防治措施上,但化学防治依然是马铃薯生产过程中防治马铃薯块茎蛾的主要方式,由于化学农药的广泛使用,该虫对有机磷类、拟除虫菊酯类等杀虫剂均产生了不同程度的抗性;为了减少化学农药的使用,延缓抗药性的发展,发现并筛选到多种对马铃薯块茎蛾具有防治作用的天敌昆虫和昆虫病原微生物。以(E4,Z7) 十三碳二烯基乙酸酯和(E4,Z7,Z10) 十三碳三烯基乙酸酯为主要成分的马铃薯块茎蛾性信息素在马铃薯块茎蛾监测和防治中也取得了较好的效果。桉树、皱叶薄荷等植物源化合物能够抑制马铃薯块茎蛾产卵;转基因抗虫马铃薯、遗传不育技术等绿色防控技术也成为了防控马铃薯块茎蛾的新方法。以往的研究发现使用单一生物防治手段很难达到理想的防控效果,集成与生物防控技术相容的化学物质、自然天敌和病原微生物等技术是有效控制马铃薯块茎蛾种群的重要趋势。本文系统综述了国内外马铃薯块茎蛾发生为害规律及综合防控技术研究进展,以期为马铃薯块茎蛾的持续治理提供参考依据。     

Contact chemoreceptors on the ovipositor of the potato moth,Phthorimaea operculella (Zell.) (Lepidoptera : Gelechiidae)

Results reported here form a part of a project in which oviposition by the potato moth, Phthorimaea operculella (Lepidoptera : Gelechiidae) is being investigated with regard to the role played by some components of the foliage of the potato plant. At least 10 chemosensilla are present on the ovipositor of the female moth, besides about 100 mechanosensilla. Each chemosensillum contains 5 dendrites, only 4 of which run up to the single, structured, terminal pore. It is likely that the chemical nature of the oviposition substrate influences the deposition of eggs.     

Resistance of wild Lycopersicon species to the potato moth, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae)

Abstract  Trichome-based host plant resistance of Lycopersicon species to potato moth, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae), was examined in a laboratory bioassay. Neonate P. operculella were placed on the foliage of accessions of L. hirsutum , L. hirsutum f. glabratum , L. pennellii , L. cheesmanii f. minor and L. esculentum for 48 h . At the end of this period, larval mortality, the numbers of larvae emigrating from, and mining into, the leaf surface were recorded as were leaf area and the densities of trichomes. Analysis by categorical logistic regression found accessions differed in levels of resistance to P. operculella ( P  < 0.001). Further analysis using generalised linear models showed mortality was associated with high densities of type VI and low densities of type V trichomes; emigration from the leaf was associated with high densities of type I and type VII trichomes; and the numbers of mines associated with low densities of type I and type VI trichomes and increased leaf area. Although results indicate that certain accessions of L. hirsutum and L. hirsutum f. glabratum may be most appropriate for inclusion in a breeding program aimed at introducing trichome-based host plant resistance of wild Lycopersicon species into the tomato, further research is necessary to fully understand the mechanisms.     

Efficacy of entomopathogenic nematodes against potato tuber moth,Phthorimaea operculella (Lepidoptera: Gelechiidae) under laboratory conditions

The susceptibility of potato tuber moth, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae) to native and commercial strains of entomopathogenic nematodes (EPNs) was studied under laboratory conditions. Native strains of EPNs were collected from northeastern Iran and characterised as Steinernema feltiae and Heterorhabditis bacteriophora (FUM 7) using classic methods as well as analysis of internal transcribed spacer (ITS) and D2/D3 sequences of 28S genes. Plate assays were performed to evaluate the efficiency of five EPN strains belonging to four species including Steinernema carpocapsae (commercial strain), S. feltiae, Steinernem glaseri and H. bacteriophora (FUM 7 and commercial strains). This initial assessment with 0, 75, 150, 250, 375 and 500 IJs/ml concentrations showed that S. carpocapsae and H. bacteriophora caused the highest mortality in both larval and prepupal stages of P. operculella, PTM. Thereafter, these three strains (i.e. S. carpocapsae, H. bacteriophora FUM 7 and the commercial strains) were selected for complementary assays to determine the effects of soil type (loamy, loamy–sandy and sandy) on the virulence of EPNs against the second (L2) and fourth instar (L4) larvae as well as prepupa. A soil column assay was conducted using 500 and 2000 IJs in 2-ml distilled water. Mortality in the L2 larvae was not affected by the EPN strain or soil type, while there was a significant interactive effect of nematode strains and soil type on larval mortality. The results also showed that EPN strains have higher efficiency in lighter soils and caused higher mortality on early larvae than that in loamy soil. In L4 larvae, mortality of PTM was significantly influenced by nematode strain and applied concentrations of infective juveniles. The larval mortality induced by S. carpocapsae was higher than those caused either by a commercial or the FUM 7 strain of H. bacteriophora. Prepupa were the most susceptible stage.     

The toxicity of some medicinal plant extracts to the potato tuber moth,Phthorimaea operculella (Lepidoptera: Gelechiidae)

The potato tuber moth Phthorimaea operculella is a serious pest of potato both in the field and storage that makes great problem in storage. Farmers routinely rely on chemical insecticides that could be hazardous for human health and environment. Insecticide resistance of P. operculella has been reported all over the world, so botanical origin materials may serve as proper alternative materials for controlling the pest. Natural products are generally preferred because of they are less harmful to non-target organisms, eco-friendly and biodegradable. In the present study, ovicidal activity of essential oils (EOs) of basil, European pennyroyal, lavender, mint, oregano and savoury and oviposition-deterrent activity of methanolic extracts of fumitory, lavender, licorice and oregano were investigated on P. operculella. Probit analysis showed that EOs of Lavandula angustifolia revealed the highest activity (LC₅₀ value 0.4 μL/L air). Fumitory extract elicited the highest reduction in percentage of laying eggs. The results indicated that these medicinal plants could be effective for declining damage of P. operculella in storages.     

延迟交配对马铃薯块茎蛾繁殖的影响

[目的]为了明确延迟交配对马铃薯块茎蛾Phthorimaea operculella Zeller繁殖的影响.[方法]在室内条件下,设置雌雄延迟交配、雄虫延迟交配和雌虫延迟交配3种处理,观察延迟交配不同天数后马铃薯块茎蛾的交配率、交配持续时间、繁殖力和成虫寿命的变化情况.[结果]在3种延迟交配的情况下,延迟交配5d的交配率均是最低,且与雌虫延迟交配相比,雄虫延迟交配和雌雄虫延迟交配对交配率的影响更明显.延迟交配对卵孵化率和产卵量均有明显的不利影响,其中雌雄延迟交配、雄虫延迟交配、雌虫延迟交配三者的均在延迟交配2d时的产卵量最高,在延迟交配5d时的产卵量最低,且两性延迟交配、雌虫延迟交配之间有显著差异.此外,受到延迟交配的影响雌雄虫寿命均有所增加,并且与单一性别对寿命的影响而言,两性延迟交配对寿命的影响更为明显,与雌虫相比雄虫更容易受到延迟交配的影响.[结论]延迟交配会对马铃薯块茎蛾的繁殖有明显不利的影响,可以对迷向法对马铃薯块茎蛾防治提供一定的参考.     

Cold tolerance characteristics of Korean population of potato tuber moth,Phthorimaea operculella (Zeller), (Lepidoptera: Gelechiidae)

Potato tuber moth (PTM), Phthorimaea operculella (Zeller), (Lepidoptera: Gelechiidae) is an invasive insect pest damaging solanaceous crops. We measured the supercooling point (SCP) and survival at low temperature of different development stages to determine which would be capable of overwintering in the Korean climate and adapting to low temperatures. The SCP ranges from ?23.8°C of the egg to ?16.8 of fourth instar larvae (L4). After short periods of low temperature acclimation in L3 (third instar larva), L4 and prepupae, only the prepupal stage showed a significant lowered SCP from ?20.78 to ?22.37°C. When exposed to different subzero temperature for two hours the egg turned out to be the most cold tolerant stage showing LT₅₀ of ?21.7°C followed by the pupal stage with ?15.89°C. One hundred percent mortality was observed when the larvae or adults were exposed to temperatures below ?15.1°C even for a period as short as 2 h. The results suggest that PTM pupae and egg would be the main overwintering stage in Korea where winter temperature does not drop below ?15°C.     

Biological effects of some natural and chemical compounds on the potato tuber moth,Phthorimaea operculella Zell. (Lepidoptera:Gelechiidae)

The olfactory reaction of larvae and moths was investigated towards 18 oils (6 natural oils and 12 commercial chemical oils). Some of these oils such as peppermint and camphor (natural oils) and eugenol and camphene (commercial oils) were repellent to both larvae and moths. Other oils such as strawberry and d-limonene were attractive to both larvae and moths.Some of the repellent oils were, therefore, tested for their effect on certain biological aspects of the insects.Eugenol and peppermint oils, each at the 0.01% conc., caused a significant depression in the fecundity of moth and decreased the percentage of egg hatchability. Eugenol oil was much more effective than peppermint oil at 1%. Dried (leaves, fruits or seeds) powder of 14 different plants species were tested in different concentrations with talcum powder (carrier material) against egg deposition. The results indicated that dried powders of Allium cepa, Curcuma longa, Colocasia antiqurum, Ocimum basilicum. Dodonaea viscose and Thuja orientalis played a highly significant role in reducing egg deposition. The most impressive effect was displayed by powders of D. viscose and A. cepa, which caused the highest depression in egg deposition as well as in the emerging offsprings. Ethanolic extracts of 11 plants indicated that extracts of Pithuranthos tortosus and Iphiona scabra caused the maximum inhibition of egg hatchability, followed by C. longa, Citrullus colocynthia and T. orientalis. Ethanolic extracts of Schinus terebenthiflius (leaves) and I. scabra caused the highest depression in the deposited eggs, as they played a remarkable role as ovipositor deterrents.The majority of the plant extracts at 1% conc. could protect potato tubers at different intervals according to the calculated tuber damage index as follows: Iphiopna > Pithuranthos > Curcuma > Schinus (fruits) Thuja > Schinus (leaves) > Dodonaea > Citrullus.     

Population biology of the potato tuber moth, Phthorimaea operculella (Lepidoptera: Gelechiidae), in two potato cropping systems in Israel

The life cycle, within-field distribution, crop damage and impact of natural enemies of the potato tuber moth, Phthorimaea operculella (Zeller) were investigated in two potato cropping systems. The two systems differed in soil type (sandy vs. loess) which in turn affected the choice of cultivars, irrigation programme, insecticide application method (ground vs. aerial), and planting and harvest times. From mid-April to the end of May, almost twice as many moths were caught in pheromone traps in sandy than in loess fields. Highest infestation of tubers was found before harvest, and infestation was greater in loess than in sandy fields. Larval densities in foliage and tubers were significantly higher at the margins of the fields than in the centre. A significant positive correlation was found between adult catch and larval infestation on foliage in sandy fields but not in loess. Tuber infestation in sand was positively correlated with foliage infestation. No such correlation was detected in loess. Five parasitic wasps emerged from P. operculella larvae collected from commercial fields and volunteer plants: Diadegma pulchripes (Kokujev) and Temelucha decorata, (Gravenhorst) (Ichneumonidae) and Bracon gelechiae Ashmead and two other unidentified Braconidae. The most abundant predators at the field site were Coccinella septempunctata Linnaeus (Coccinellidae), Chrysoperla carnea Stephens (Chrysopidae), Orius albidipennis (Reuter) (Anthocoridae) and four ant species (Formicidae). Parasitism rate reached 40% and predation was estimated at 79%. Results are discussed with regard to the development of an integrated pest management programme for this important pest.     

Tomato fruit size, maturity and alpha-tomatine content influence the performance of larvae of potato tuber moth Phthorimaea operculella (Lepidoptera: Gelechiidae)

Various physical and chemical properties of host plants influence insect larval performance and subsequent adult fitness. Tomato plants are relatively new hosts to the potato tuber moth, Phthorimaea operculella (Zeller), with the fruit being its preferred feeding site. However, it is unclear how the biochemical and physical properties of tomato fruits relate to potato tuber moth performance. Significant amounts of alpha-tomatine were detected in maturing green and ripening fruits of cherry (cv. Ceres) and processing (cv. Serio) types of tomatoes whereas none was detected in a fresh market variety (cv. Marglobe), at comparable stages. alpha-Tomatine is negatively and significantly correlated with development rate (head capsule size) of larvae reared in the fruits of the cherry and processing type tomatoes. Generally, survival, growth and development were significantly superior for larvae reared in the ripening fruits of the fresh market cultivar. At this stage, the fruits of this cultivar are also the largest. Based on these results it is concluded that fruit alpha-tomatine content, as well as fruit size and maturity, all affect performance of P. operculella larvae in the fruits of cultivated tomatoes.     

Establishment of Beauveria bassiana as a fungal endophyte in potato plants and its virulence against potato tuber moth,Phthorimaea operculella (Lepidoptera: Gelechiidae)

The potato tuber moth, Phthorimaea operculella, is the most damaging potato pest in the world and is difficult to control as the larvae are internal feeders in the foliage and tubers. Entomopathogenic fungi that colonize plants as endophytes have lethal and sublethal pathological effects on insect pests. We show that Beauveria bassiana colonizes the aerial parts of potato plants endophytically after inoculation through soil drenching. Endophytic B. bassiana persisted in potato foliage for more than 50 days postinoculation. Bioassays indicated that foliage of B. bassiana-inoculated potato plants were pathogenic against larvae of P. operculella. Sublethal experiments indicated that B. bassiana negatively affected the growth, development, and reproduction of P. operculella. Development experiments showed that the weight of P. operculella pupae reared on B. bassiana-colonized potato plants (4.25 mg) was significantly less than that of those reared on uninoculated control plants (8.89 mg). Compared with newly eclosed larvae fed on control plants, those fed on B. bassiana-inoculated plants had significantly lower survivorship, with only 17.8% developing to the adult stage. Oviposition of P. operculella females reared on B. bassiana endophytically colonized plants was significantly lower (35 eggs/female) than of those reared on uninoculated plants (115 eggs/female). This study demonstrates that endophytic B. bassiana can be a potential biological control agent for the control and management of P. operculella. Comparing pupal weights of P. operculella reared on potato plants inoculated with the B. bassiana strain GZGY-1-3 and on untreated control plants, pupae from the control plants were significantly heavier than those from treated plants.     

Estimating temperature‐dependent developmental rates of potato tuberworm,Phthorimaea operculella (Lepidoptera: Gelechiidae)

Abstract The potato tuberworm, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae), is the most destructive pest of potato, Solanum tuberosum L. (Solanaceae), in tropical and subtropical regions in both field and storeroom situations. The modeling of temperature‐dependent development can be useful in forecasting occurrence and population dynamics of the pests. Published developmental parameters for this pest vary greatly for many reasons. We determined temperature‐dependent development of P. operculella at seven constant temperatures (16, 20, 24, 28, 32, 34 and 36 °C). Developmental period of whole immature stage (egg to the end of the pupal stage) varied from 75.5 days at 16 °C to 17 days at 32 °C. The population failed to survive at 36 °C. The observed data was modeled to determine mathematical functions for simulating P. operculella development in each stage of development and overall. Two linear models, ordinary linear regression and the Ikemoto linear model were used to describe the relationship between temperature and development rate of the different stages of P. operculella and estimating the thermal constant and lower temperature threshold. The lower temperature threshold (t) and thermal constant (k) of whole immature stage were estimated to be 11.6 °C and 338.5 DD by Ikemoto linear model, and the estimated parameters were not substantially different with those estimated by ordinary linear models. Different models provided a better fit to the various developmental stages. Of the eleven nonlinear models fitted, the Beriere‐1, Logan‐6 and Lactin‐1 model was found to be the best for modeling development rate of egg, larva and pupa of P. operculella, respectively. Phenological models based on these findings can be part of a decision‐support tool to improve the efficiency of pest management programs.     

Oviposition of potato tuber moth,Phthorimaea operculella Zell. (Lepidoptera: Gelechiidae); identification of host-plant factors influencing oviposition response

Abstract

A series of laboratory experiments was conducted to investigate the nature of the factors which determine acceptance or rejection of plants for oviposition by potato tuber moth. Bare leaves of only two plant species (potato and egg-plant) were accepted for oviposition, but when covered with a layer of muslin, leaves of all plants examined—including several known non-host plants—were rendered acceptable. Thus, volatile repellent factors are not possessed by unacceptable plants; rather, they must be rejected either because of chemical deterrents detectable only on contact or because of unsuitably textured surfaces. Plant juices expressed on to a covering layer of muslin increased the acceptance of potato and egg-plant, had no effect with tobacco, and decreased acceptance of all known non-host plants and of tomato. Brushing the leaf surface without releasing plant juices induced a detectable deterrent effect with some plant species. There was no stimulation or deterrence when the oviposition surface was separated from expressed plant juices by about 2 mm. Tomato reacted like known non-host plants in all tests. Potato and egg-plant stimulated greater total egg deposition in most experiments, but strongly deterrent treatments did not reduce the total egg lay. Antennectomy reduced but did not eliminate the stimulatory effect of potato and the deterrent effect of bean plant juices. Virgin moths were not stimulated to oviposit by potato peel. It is concluded that selection of plants for oviposition is determined both by the physical nature of their surfaces and by chemical factors which are detected only on contact. The effects of stimulative chemical factors in host plants and deterrent factors in non-host plants reinforce each other in the plant selection process.     

Histopathology and effect on development of the PhopGV on larvae of the potato tubermoth, Phthorimaea operculella (Lepidoptera: Gelechiidae)

Larvae of the potato tubermoth (PTM), Phthorimaea operculella, feed on potato plants and tubers and are a major pest in the tropics and subtropics worldwide, causing up to 100% damage. The PTM granulovirus (PhopGV) provides significant potato protection, but little is known about its effect on larval development or its histopathology. Here we show that only 10% of larvae exited from PhopGV-treated tubers (1.4 × 10⁸ granule/ml), lagging significantly behind controls, and most of these died by 72 h after emergence. Histopathology studies showed the fat body and epidermis were the principal tissues infected. PhopGV morphogenesis was similar to other GVs, the exception being small vesicles between mature granules.     

Search behavior of pheromone-stimulated potato tuber moth males (Lepidoptera: Gelechiidae)

The processes of female searching by male potato tuber moths,Phthorimaea operculella, were analyzed. The behavioral components to copulation were antennal cleaning, quiescence, walking, wing fanning, contact with female, hair brush display, copulation attempt, and copulation. Males did not always succeed in mating on their first attempt. Searching behavior of males changes to “area-restricted searching” after contact with a female. Males could, therefore, find females efficiently and copulate.     

Tethered flight of the potato moth, Phthorimaea operculella

ABSTRACT. The effects of sex, age and mated state on average flight speed, duration and distance were determined for potato moths, Phthorimaea operculella (Zeller) (Lepidoptera, Gelechiidae), tethered to flight mills. Moths were classified as non-fliers (NFs), good-fliers (GFs) and remaining-fliers (RFs) on the basis of their performance over the first two flights. Some moths flew for over 5 h non-stop, while others tethered overnight flew between 20 and 30 km. Speed, duration and distance flown were greater during the first flight. First flight duration and distance flown by females decreased with age, whereas no trend was evident for males. Mated males and females flew slower first flights with increasing age, whereas virgin moths showed no marked trend. The analysis of fliers and NFs revealed that GFs were heavier than both RFs and NFs, GFs were faster than RFs, the percentage of NFs increased with age especially for mated females, and the percentage of GFs decreased with age. Age and mated state are important factors influencing flight performance especially for female moths. The relevance of these results to the field situation and the possible application of tethered flight to tests of potato moth quality are discussed.     

Age-specific bioassays and fecundity of Phthorimaea operculella (Lepidoptera: Gelechiidae) reared on cry1Ac -transgenic potato plants

Variation in the susceptibility of lepidopterous pest larvae of different ages to transgenic crops and the potential for survivors to reproduce could have important consequences for the development of resistance in such pests. Experiments were undertaken in the laboratory to determine if larvae of the potato tuber moth, Phthorimaea operculella, of different ages (0 (< 1 day old), 3, 5, 7 days) varied in their susceptibility to cry1Ac9–transgenic potato (Solanum tuberosum) foliage grown in the glasshouse or field. The survival and fecundity of larvae reared on transgenic tubers was also determined in the laboratory. There were no apparent differences in susceptibility of larvae of different ages to transgenic foliage. Larvae fed glasshouse or field‐grown non‐transgenic foliage had significantly larger relative growth indices and more larvae pupated, than those fed transgenic foliage, regardless of larval age. Eggs from a laboratory colony were placed on transgenic or non‐transgenic tubers to measure survival and fecundity. Between 6% and 15% of eggs placed on transgenic tubers developed into pupae for three of the four transgenic potato lines tested. On one transgenic line, only six adults emerged from 1300 eggs. In contrast, between 71% and 97% of the eggs placed on non‐transgenic tubers developed into pupae. Male and female pupae from transgenic lines weighed less than those from non‐transgenic lines. The fecundity of females from two of four transgenic lines was lower than from the non‐transgenic parent cultivar. Although larvae of different ages did not exhibit any overall age‐dependent pattern of increasing or decreasing susceptibility to transgenic foliage of glasshouse or field‐grown plants, the ability of larvae to survive and reproduce on transgenic tubers suggests this pest has the ability to evolve resistance to the transgenic plants used in the present study.