THE INFLUENCE OF CULTURAL PRACTICE ON POPULATION OF PEA LEAFMINER (Liriomyza huidobrensis) AND ITS PARASITOIDS IN POTATO

Pea leafminer (Liriomyza huidobrensis) is the major pest of potato crop in Indonesia. The use of insecticides to control the pest is ineffective and harmful to the natural enemies. The study aimed to find out a promising cultural practice for leafminer management on potato crop. The study was conducted at a farmer’s field in Bali in 2004. Potato plants (Granola variety) were grown in a raised-bed plot of 10 m x 1 m. The treatments evaluated were standard cultural practice (C), C plus reflective plastic mulch (RPM) (CM), farmer’s practice (F), vermicompost (V), and V plus RPM (VM). All treatments were arranged in RCBD with five replications. From each plot, 10 plant samples were randomly taken to observe the presence of larvae, mines, and adults. Larvae and adults of leafminer and mines were separately counted from the top, middle, and bottom parts of the plant samples. Parasitoids were collected from the infested leaves of the plant samples. Emerged parasitoids were counted and put into vials with 70% ethyl alcohol and then identified. The results showed that the population of adults, larvae of L. huidobrensis, and mines were less in C, CM, V, and VM treatments compared to farmer's practice (F). However, RPM (CM and VM) treatments significantly reduced population of leafminer and mines. The highest population of adults, larvae, and mines on RPM treatment were less than 1.5, 8.5, and 10 per plant, respectively compared to other treatments which were greater than 3.2 for adults, 12.4 for larvae, and 12.7 for mines. Parasitoid population and parasitism level were more in vermicompost treatments (V and VM) compared to other treatments (C, CM, and F). The results showed that application of pesticides was ineffective against leafminer and reduced parasitoid population; in the other hand RPM was effective to control leafminer although the effect on parasitoids was not clear. Parasitoid species that were found associated with potato crop were Hemiptarsenus varicornis, Neochrysocharis sp., and Opius sp. Combination of RPM with standard practice and vermicompost are prospective for leafminer management in potato crop, however, VM is friendlier to environment regarding sustainable agriculture

THE INFLUENCE OF CULTURAL PRACTICE ON POPULATION OF PEA LEAFMINER (Liriomyza huidobrensis) AND ITS PARASITOIDS IN POTATO

Pea leafminer (Liriomyza huidobrensis) is the major pest of potato crop in Indonesia. The use of insecticides to control the pest is ineffective and harmful to the natural enemies. The study aimed to find out a promising cultural practice for leafminer management on potato crop. The study was conducted at a farmer’s field in Bali in 2004. Potato plants (Granola variety) were grown in a raised-bed plot of 10 m x 1 m. The treatments evaluated were standard cultural practice (C), C plus reflective plastic mulch (RPM) (CM), farmer’s practice (F), vermicompost (V), and V plus RPM (VM). All treatments were arranged in RCBD with five replications. From each plot, 10 plant samples were randomly taken to observe the presence of larvae, mines, and adults. Larvae and adults of leafminer and mines were separately counted from the top, middle, and bottom parts of the plant samples. Parasitoids were collected from the infested leaves of the plant samples. Emerged parasitoids were counted and put into vials with 70% ethyl alcohol and then identified. The results showed that the population of adults, larvae of L. huidobrensis, and mines were less in C, CM, V, and VM treatments compared to farmer's practice (F). However, RPM (CM and VM) treatments significantly reduced population of leafminer and mines. The highest population of adults, larvae, and mines on RPM treatment were less than 1.5, 8.5, and 10 per plant, respectively compared to other treatments which were greater than 3.2 for adults, 12.4 for larvae, and 12.7 for mines. Parasitoid population and parasitism level were more in vermicompost treatments (V and VM) compared to other treatments (C, CM, and F). The results showed that application of pesticides was ineffective against leafminer and reduced parasitoid population; in the other hand RPM was effective to control leafminer although the effect on parasitoids was not clear. Parasitoid species that were found associated with potato crop were Hemiptarsenus varicornis, Neochrysocharis sp., and Opius sp. Combination of RPM with standard practice and vermicompost are prospective for leafminer management in potato crop, however, VM is friendlier to environment regarding sustainable agriculture

The Influence of Cultural Practice on Population of Pea Leafminer (Liriomyza Huidobrensis) and Its Parasitoids in Potato

Pea leafminer (Liriomyza huidobrensis) is the major pest of potato crop in Indonesia. The use of insecticides to control the pest is ineffective and harmful to the natural enemies. The study aimed to find out a promising cultural practice for leafminer management on potato crop. The study was conducted at a farmer's field in Bali in 2004. Potato plants (Granola variety) were grown in a raised-bed plot of 10 m x 1 m. The treatments evaluated were standard cultural practice (C), C plus reflective plastic mulch (RPM) (CM), farmer's practice (F), vermicompost (V), and V plus RPM (VM). All treatments were arranged in RCBD with five replications. From each plot, 10 plant samples were randomly taken to observe the presence of larvae, mines, and adults. Larvae and adults of leafminer and mines were separately counted from the top, middle, and bottom parts of the plant samples. Parasitoids were collected from the infested leaves of the plant samples. Emerged parasitoids were counted and put into vials with 70% ethyl alcohol and then identified. The results showed that the population of adults, larvae of L. huidobrensis, and mines were less in C, CM, V, and VM treatments compared to farmer's practice (F). However, RPM (CM and VM) treatments significantly reduced population of leafminer and mines. The highest population of adults, larvae, and mines on RPM treatment were less than 1.5, 8.5, and 10 per plant, respectively compared to other treatments which were greater than 3.2 for adults, 12.4 for larvae, and 12.7 for mines. Parasitoid population and parasitism level were more in vermicompost treatments (V and VM) compared to other treatments (C, CM, and F). The results showed that application of pesticides was ineffective against leafminer and reduced parasitoid population; in the other hand RPM was effective to control leafminer although the effect on parasitoids was not clear. Parasitoid species that were found associated with potato crop were Hemiptarsenus varicornis, Neochrysocharis sp., and Opius sp. Combination of RPM with standard practice and vermicompost are prospective for leafminer management in potato crop, however, VM is friendlier to environment regarding sustainable agriculture

Ecology and biocontrol options of the leaf miner, liriomyza huidobrensis, on potatoes in the Western Cape province

Thesis (MScConsEcol)--Stellenbosch University, 2021.ENGLISH ABSTRACT: The potato leaf miner, Liriomyza huidobrensis Blanchard (Diptera: Agromyzidae), is a devastating pest of potatoes, worldwide. However, little knowledge of the biology and ecology of this pest in South Africa exists, with both factors being cardinal elements in implementing an effective integrated pest management (IPM) programme. Control of the pest relies on the extensive use of chemical insecticides. Concerns regarding insect resistance, human safety and environmental impacts have, however, encouraged the development and use of alternative environmental control strategies, including the use of entomopathogenic nematodes (EPNs) and fungi (EPF). The present study focuses on the population dynamics of L. huidobrensis during the winter and summer period, a parasitoid survey and biological control using EPNs and EPF. The study showed differences in adult leaf miner populations in both the potato fields and the natural vegetation for both the winter and summer monitoring periods. The abundance and population densities of leaf miners increased during summer, while being very low during the winter monitoring period. The observed trend was that the leaf miner populations increased during crop development, with damage regularly being spotted on the potato leaves two weeks after plant emergence. Five parasitoid species associated with L. huidobrensis were identified during the monitoring periods, with Diglyphus isaea being the most abundant species. After assessing the occurrence of entomopathogens in the soil samples collected from the potato fields, one EPN species Heterorhabditis zealandica, one insect-associated nematode Acrobeloides sp. and two EPF species, Metarhizium robertsii and Metarhizium majus were isolated from the 16 surveyed potato fields. Four EPN species were screened for pathogenicity against the larval and pupal stages using different concentrations of infective juveniles (IJs) in the laboratory, which included Heterorhabditis bacteriophora, Heterorhabditis baujardi and Steinernema yirgalemense and which were obtained from the collection of the Department of Conservation Ecology and Entomology, Stellenbosch University, with the fourth species Heterorhabditis zealandica being isolated from the potato fields. The pathogenicity results of all the EPNs at 200 IJs/50 μl of distilled water solution indicated insect mortality of > 40 % for both the leaf mining larvae and the pupae. However, pupae and larvae trials indicated that the best performing treatment was found to be H. baujardi with more than 57 % of pupae mortality and > 71 % larvae mortality. The findings, thus, indicate the EPNs potential for adoption as part of an IPM strategy. On the other hand, two different species of EPF, namely Metarhizium robertsii and Beauveria bassiana, were tested for pathogenicity against the pupae of the potato leaf miner. The EPF were able to cause 67 % mortality. The study also screened five different isolates of M. robertsii found during the monitoring period, with the results obtained indicating very high pupae mortality of more than 80 % of pupae. The study provided a positive forecast for the management of potentially damaging populations using entomopathogens as biocontrol agents against L. huidobrensis, in potato cultivation, in South Africa. This study was a laboratory assessment and thus a first step towards further development of a management strategy.AFRIKAANSE OPSOMMING: Die aartappelblaarmyner, Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae), is 'n ernstige pes van aartappels wêreldwyd. Daar is egter min bekend oor die biologie en ekologie van hierdie pes in Suid-Afrika en beide hierdie faktore is van kardinale belang vir die implementering van ʼn effektiewe geïntegreerde pesbeheerstelsel (IPM). Die bestryding van die L. huidobrensis is afhanklik die gebruik van chemiese insekdoders. Insekweerstand, menslike veiligheid en die effek op die omgewing het egter die ontwikkeling en gebruik van alternatiewe omgewingsbeheerstrategieë aangemoedig, insluitend die gebruik van entomopatogeniese nematodes (EPNs) en entomopatogeniese fungi (EPF). Hierdie studie fokus op die bevolkingsdinamika van L. huidobrensis gedurende die winter en somer, 'n parasitoïed opname en biologiese beheer met behulp van EPNs en EPF. Die studie het verskille getoon in die populasies van blaarmyners by volwassenes, in beide die aartappellande en die natuurlike plantegroei gedurende die winter- en somer moniterings periodes. Die bevolkingsgetalle en digtheid van blaarmyners het gedurende die somer toegeneem, terwyl dit gedurende die winter moniterings periode baie laag was. Die waargenome tendens was dat die blaarmynerpopulasies toegeneem het tydens gewas ontwikkeling, met skade wat gereeld op die aartappelblare opgemerk is twee weke na die opkoms van plante. Vyf parasitoïed spesies, wat verband hou met L. Huidobrensis, is tydens die moniteringstydperke geïdentifiseer, met Diglyphus isaea wat die mees algemeen waargeneem is. Nadat die voorkoms van entomopatogene in grondmonsters wat van 16 aartappellande versamel is, vasgestel is, is die volgende spesies geïsoleer: een EPN spesie naamlik, Heterorhabditis zealandica, een insek geassosieerde nematode, Acrobeloides sp. en twee EPF spesies, Metarhizium robertsii en Metarhizium majus. Vier EPN spesies is in die laboratorium vir patogenisiteit teen die larwale- en papiestadia getoets deur verskillende konsentrasies van infektiewe larwes (IJ's) te gebruik. Hierdie spesies sluit in: Heterorhabditis bacteriophora, Heterorhabditis baujardi en Steinernema yirgalemense wat verkry is uit die versameling van die Departement van Bewaringsekologie en Entomologie, Universiteit Stellenbosch. Die vierde spesie, H. zealandica is van die aartappellande geïsoleer. Die patogenisiteitsresultate van al die EPNs met ʼn konsentrasie van 200 IJs / 50 μl gedistilleerde water dui op insekmortaliteit van >40% vir beide die blaarmyner larwes en die papies. Papie- en larfproewe het egter aangedui dat H. baujardi die beste behandeling is met meer as 57% van die papiesterftes en >71% larvale mortaliteit. Die bevindinge dui dus op die potensiaal vir aanvaarding van EPNs as deel van 'n IPM-strategie. Twee verskillende soorte EPF, naamlik Metarhizium robertsii en Beauveria bassiana, is ook getoets vir hul vatbaarheid teen die papies van die aartappelblaarmyner. Die EPF kon tot 67% mortaliteit veroorsaak. Vyf verskillende isolate van M. robertsii, wat gedurende die moniteringstydperk gevind is, getoets en die resultate dui op 'n baie hoë papiemortaliteit van meer as 80%. Die studie dui daarop dat entomopatogene as biobeheermiddels die potensiaal het om baie suksesvol te wees vir die beheer van skadelike populasies van L. huidobrensis in aartappelverbouing in Suid-Afrika. Hierdie studie was 'n laboratorium assessering, en dus 'n eerste stap in die verdere ontwikkeling van 'n bestuurstrategie vir L. huidobrensis.Master

A Review of Leaf-mining Insects and Control Options for their Management, with Special Reference to Holocacista capensis (Lepidoptera: Heliozelidae) in Vineyards in South Africa

A leaf-mining pest occurring on commercial varieties of Vitis vinifera in South Africa was investigated due to the presence of cocoons on fruit. The leaf miner, Holocacista capensis, was reported on grapevines in 2012. Since its discovery on commercial grape varieties, control strategies have consisted solely of insecticide applications. Despite the fact that the leaf-mining habit is taxonomically diverse and considered ancient, little is generally known of leaf-mining larvae. A review was conducted in order to better understand the leaf-mining strategy and amalgamate the current knowledge of other leaf-mining insects.  The general evolutionary history within the full complement of taxa that display the leaf-mining habit is discussed. The review focuses on lepidopteran leaf-mining pests and discloses the known information associated with the first report and the impact of H. capensis in the Western Cape, South Africa. As no control methods have been identified for H. capensis in vineyards, various chemical, biological and cultural control strategies adopted for other leaf-mining pests were investigated. Control options, including theuse of entomopathogenic nematodes (EPNs), parasitoids, physical and cultural control measures, were considered and are discussed. Alternate control methods are pertinent for the grape-growing industry to avoid the development of the insecticide resistance that is common amongst leaf miners. This review aims to consolidate the available literature and therefore aid in the development of an integrated pest management strategy to effectively control H. capensis in infested vineyards in South Africa

LIRIOMYZA LEAFMINERS, ASSOCITED PARASITOIDS AND INSECTICIDE EVALUATION IN SOUTH TEXAS

In the Lower Rio Grande Valley of Texas, dipterous leafminers cause damage to pepper crop by destroying small plants (excessive mining), reduction of yield, and by vectoring plant diseases. The objectives of the present research were to identify leafminers species, which cause damage to peppers in South Texas, their associated parasitoid guilds and to evaluate the efficacy of abamectin, novaluron, spinetoram and lambda-cyhalothrin against leafminers as well as their effects on the parasitoid complex. Field surveys were conducted on various pepper varieties in different cities of South Texas. Insecticide evaluation was carried out on field plots in Weslaco TX using the different insecticide treatments and water. To determine the insecticides? lethal effects on adult leafminer parasitoids, Neochrysocharis formosa and Ganaspidium nigrimanus, laboratory bioassays, such as topical insecticide application, pesticide intake and residual effects were performed. The surveys suggested that the leafminers causing the most damage to pepper crops in South Texas is Liromyza trifolii, which represents more than 99% of the collected and identified species. Twenty parasitoid species, of four different families, were found to be attacking L. trifolii on pepper plants in the field. Novaluron was the most effective insecticide in controlling L. trifolii, followed by spinetoram and abamectin. Lambda-cyhalothrin was the least effective, showing L. trifolii tolerance to the compound. In field evaluation novaluron showed the lowest parasitoid: leafminer larvae ratio and parasitoid diversity index. In contrast, novaluron had the least impact on adult parasitoids in laboratory bioassays compared with other treatments (abamectin, spinetoram, lambdacyhalothrin). The lambda-cyhalothrin showed negative effects only to Ganaspidium nigrimanus in topical assays, but in the residual assays it had negative effects on G. nigrimanus as well as N. formosa. On the other hand, abamectin showed negative effects on N. formosa and G. nigrimanus in the topical and intake bioassays and negative effects on G. nigrimanus but no-effect on N. formosa in the residue bioassay. Furthermore spinetoram showed negative effects on N. formosa and G. nigrimanus in all bioassays carried out in the laboratory. Leafminer species, parasitoid species composition, efficacy of insecticides, effects of insecticides on parasitoids and development of tolerance to lambda-cyhalothrin by L. trifolii and N. formosa were discussed

On seasonal inoculative biological control : [governing Liriomyza populations by parasitoids]

The main purpose of the research project was to develop a biological control method for the imported leafminer Liriomyza trifolii and its native relative Liriomyza bryoniae on greenhouse tomato.In addition, the project attempted to study the population dynamics of the leafminers and their parasitoids by determining the processes that lead to changes in population densities. Several factors, such as temperature and host plant quality in terms of leaf nitrogen content, were examined.Using leafminer parasitoids as a model, four criteria were examined to select parasitoids prior to their introduction in seasonal inoculative biological control. These are:Complete development and offspring quality.Generation synchrony.Population growthSearching efficiencyThese criteria were evaluated for the European leafminer parasitoids Dacnusa sibirica and Dacnusa isaea .</p

Biological control of tomato leaf miner Tuta absoluta using entomopathogenic nematodes

PhD ThesisIncreasing resistance to chemical insecticides in field populations of tomato leafminer, Tuta absoluta, has motivated research on alternative control measures. Biological control with entomopathogenic nematodes (EPNs) can be an alternative, particularly against larval instars. In foliar application, EPNs encounter many factors that affect their survival and efficacy adversely. This thesis has investigated: (1) the efficacy of some commercial EPNs against different stages of Tuta absoluta (larvae, pupae and adults) in Petri dish, leaf and soil bioassays, (2) factors affecting EPNs on tomato leaves and (3) impact of some organic and non-organic adjuvants on efficacy of EPNs at 75 ± 10 % and 45 ± 10 % RH. Results showed high adult and larval mortality of Tuta absoluta using Steinernema feltiae, Steinernema carpocapsae and Heterorhabditis bacteriophora in dish and leaf bioassays in optimum conditions (> 90 % RH). S. feltiae was the most virulent species, followed by S. carpocapsae then H. bacteriophora. Larval susceptibility increased throughout larval development. Pupae in contrast were less susceptible to nematode infection. In soil, S. feltiae and S. carpocapsae were significantly more virulent than H. bacteriophora against fourth larval instar when they drop to pupate in the soil and against adults when they are emerging from pupae. All factors studied (relative humidity, temperature, repeat application, method of application and time for EPNs to enter a leaf) affected the efficacy of EPNs to some extent, but relative humidity (RH) was the most important factor. EPNs’ efficacy and survival decreased as RH declined. The addition of Barricade® II and xanthan gum to aqueous suspensions of S. feltiae and S. carpocapsae resulted in increasing their efficacy and survival. What is more, they reduced the loss of nematodes into the soil in run-off by depositing them on the leaf and they assured even distribution of nematodes in the spray tank by preventing them from settling down. Moreover, Barricade® II (1.5 %) reduced the time required by S. feltiae and S. carpocapsae to enter a leaf. Barricade® II is the candidate adjuvant to be used with S. feltiae for foliar application against T. absoluta.The Libyan Ministry of Higher Educatio