Tomato Varieties Influence the Performance of Tamarixia triozae (Hymenoptera: Eulophidae) on Bactericera cockerelli (Hemiptera: Triozidae) Nymphs (original) (raw)
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Journal of Economic Entomology, 2015
The potato psyllid, Bactericera cockerelli (šulc), has been detrimental to potato, tomato, and other solanaceous crop production in many countries. Management of B. cockerelli is dominated by frequent insecticide applications, but other approaches need consideration, including biological control. The sole arrhenotokous ectoparasitoid of nymphal potato psyllids is Tamarixia triozae (Burks) (Hymenoptera: Eulophidae). Here, laboratory evaluations of host stage preference, parasitoid mutual interference, and functional response of T. triozae were conducted with varying host B. cockerelli nymphal stages and densities on both tomato and bell pepper plant leaves. Significant differences in prey stage preferences were found on both host plants. In a no-choice host stage test, significantly greater parasitism of fourth-and fifth-instar B. cockerelli nymphs occurred, and no parasitism of first or second instars was found. Similar preferences were found in a host stage choice test. Effect of mutual interference on per capita female parasitism was significant when confining two or three simultaneously ovipositing female T. triozae adults on a given host density versus solitary females. The per capita search efficiency (s) of female T. triozae was significantly and negatively correlated with T. triozae density. The functional response of T. triozae to nymphal B. cockerelli was a Type III form on both host plants. In addition, host plant type did not exert a significant bottom-up effect on either parasitism or functional response of female T. triozae. The feasibility of using bell pepper as a potential banker plant for T. triozae augmentation is also discussed.
Environmental Entomology, 2015
The parasitism and host feeding behavior of Tamarixia triozae (Burks) (Hymenoptera: Eulophidae) females on Bactericera cockerelli (Sulc) (Hemiptera: Triozidae) fourth instars that have infested tomato (Lycopersicon esculentum Miller) leaflets are described and quantified. Females took approximately 31.14 6 4.39 min to search for their first suitable host. The recognition and handling times for oviposition were 2.66 6 0.18 and 4.26 6 0.39 min, respectively. T. triozae parasitized 4.66 6 0.61 nymphs in a period of 6 h. The parasitoid explored and probed its host by walking along the margins of its body while antennating and repeatedly introducing the ovipositor beneath the nymph. The handling times before and during host feeding were 8.42 6 0.67 and 8.29 6 0.60 min, respectively. T. triozae females consumed 1.00 6 0.00 B. cockerelli nymph after parasitizing 3.3 6 0.48 nymphs. EPA-a refined soybean oil-imidacloprid, and abamectin caused between $70 and 100% T. triozae adult mortality after a 48-h contact treatment with fresh pesticide residue and a 47-91% decrease (abamectin > imidacloprid > EPA) in adult emergence when parasitized B. cockerelli fourth instars were directly sprayed. These data suggest that the use of these insecticides in combination with T. triozae in integrated pest management programs should be carefully evaluated.
Agrociencia, 2008
The tomato-potato psyllid, Bactericera cockerelli (Sulc.), is one of the most important pests of chili pepper (Capsicum spp.), tomato (Lycopersicon esculentum Mill.), and potato (Solanum tuberosum L.) in Mexico. Insecticides are used for its control, and the farmers perceive that their biological effectiveness is not satisfactory. In nymphs, LC50, LC95, confidence limits at 95%, values of resistance ratio at a level of LC50 (RR50) and LC95 (RR95) to six insecticides were determined in one susceptible and two field-collected populations (El Huizache, State of San Luis Potosi, and Arteaga-Galeana of Coahuila and Nuevo Leon). All the populations were susceptible to fenpropathrin, abamectin, cyfluthrin, dimetoate, esfenvalerate, and pyriproxyfen. It is documented that the lack of biological effectiveness in field is not due to resistance to insecticides.
2014
Host plant preferences of the potato psyllid B. cockerelli among wild and cultivated solanaceous hosts in the Lower Rio Grande Valley of Texas, and transmission of the endosymbiotic bacterial pathogen, 'Candidatus Liberibacter solanacearum' (Lso) were evaluated. Settling and ovipositional behavior of B. cockerelli was studied to determine preference for potato, tomato, pepper, eggplant and silverleaf nightshade (SLN) hosts. Results of field testing indicate resident B. cockerelli preferred potato and tomato equally for settling and oviposition, moving to pepper, eggplant and SLN only in the absence of potato and tomato. However, under laboratory conditions B. cockerelli adults preferred eggplant, pepper and potato equally, and more than tomato and SLN. Based on psyllid abundance, B. cockerelli were more active during the morning and less active during the afternoon. Preference for larger hosts in terms of size was exhibited, irrespective of the host. Growth and survival of B. cockerelli was better on potato than SLN. Lso-infectivity influenced nymphal survivorship and Lso-free individuals survived better than Lso-infective on both potato and SLN. Contrary to our hypothesis and published literature, psyllids preferred uninfected hosts and, in most cases, did not exhibit any preference for Lso-infected or uninfected potato, tomato or pepper. Results from field studies demonstrated that significantly more resident psyllids settled on uninfected potato plants than Lso-infected plants. Although previous results indicate the importance of olfactory cues to guide psyllid orientation to hosts, our results demonstrate that psyllids more likely use visual cues, preferring healthy and vigorous instead of sick iii and dying hosts. B. cockerelli acquired Lso from infected SLN, becoming infective within two weeks and transmitted Lso back to potato. It remains unclear if SLN retains Lso after exposure to temperatures routinely >35˚C. Findings from this study will lead to useful information that can be used in a attract-and-kill scenario by attracting B. cockerelli adults to preferred hosts that can be used as a trap crop near potato fields. Results further highlight mechanisms that psyllids adopt in making choices for preferred hosts and opens up avenues for establishing host preference study protocols. iv DEDICATION I dedicate this dissertation to my loving mother for her constant support, advice and unconditional love. v ACKNOWLEDGEMENTS Bless the Lord O my soul, Bless His holy name; Bless the Lord O my soul, and forget not all His benefits;-Psalms 103:1,2 Graduate education is not only exhilarating, but also an arduous path, and I set out on this path with an absolute commitment and mindset to excel. With my innate interest and strong motivation for research, it was my privilege and lifetime opportunity to pursue a Ph.D at Texas A&M University in the field of Horticulture in acquaintance with its renowned faculty members. Words are boundless to express my indebtedness and gratitude to Dr. Don Henne, my advisor and co-chair of my dissertation committee, who gracefully accepted me in his program as a transfer student. His calm demeanor and pleasant disposition truly inspired me. He was a man of few words but, was always willing to discuss my research questions. He encouraged and expected me to think more independently about my experiments and results. Truly I can say, that I gained his trust as he gave me the autonomy to work, the freedom to speak, and the unique opportunity to get trained on several techniques and methods. I am certainly at loss of words to express how much I owe Dr. Henne for his compassion and understanding of my role as a student and single mother. My sincerest thanks to Dr. Betsy (Elizabeth) Pierson, chair of my dissertation committee, for taking a keen interest in my academic and personal development. Her professional insight and acumen were instrumental in bringing out the best in me. I deeply appreciate the constructive criticisms and critical suggestions offered at each and vi every phase. My special appreciation and thanks are due to the members of my dissertation committee, Drs. Jifon, Tamborindeguy and Miller who were always supportive of me during my good times and bad, encouraging and motivating me with my research that allowed me to grow as a research scientist. Their insightful contributions greatly improved my research.
Journal of economic entomology, 2018
Lethal and sublethal effects of refined soybean oil, imidacloprid, and abamectin on Tamarixia triozae (Burks; Hymenoptera: Eulophidae) were assessed after exposure of the eggs, larvae, and pupae of this parasitoid to three concentrations of these active substances: the LC50 for fourth-instar Bactericera cockerelli (Sulc.; Hemiptera: Triozidae) and 50% and 100% of the minimum field-registered concentration (MiFRC). Soybean oil caused 26-61% mortality in T. triozae eggs and 6-19% in larvae; mortality in both eggs and larvae was ≤19% for imidacloprid and 4-100% for abamectin. All three compounds caused <18% mortality of T. triozae pupae, with the exception of the abamectin 50% (47%) and 100% (72%) MiFRC. The mortality of larvae and pupae derived from treated eggs was ≤39% for all three insecticides, and that of pupae derived from treated larvae was ≤10%. In general, emergence of adults developed from treated eggs, larvae, and pupae was affected more by abamectin than by the other tr...
Journal of economic entomology, 2013
The South American tomato leafminer, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), is a major pest that has recently invaded Afro-Eurasia. Biological control, especially by Trichogramma parasitoids, is considered to be promising as a management tool for this pest. However, further development of Trichogramma-based biocontrol strategies would benefit from assessing the impact of released parasitoid offspring on the pest. Under laboratory conditions, we 1) compared the parasitism of five Trichogramma species-strains on the pest-plant system T. absoluta-tomato, and 2) assessed various biological traits of parasitoids, mass-reared on a factitious host (Ephestia kuehniella Zeller), when developing on T. absoluta. In addition, we evaluated the overall efficiency of two specific Trichogramma species when released under greenhouse conditions in combination with a common natural enemy in tomato crop, the predator Macrolophus pygmaeus Rambur. Parasitoids emerging from T. absoluta on tomat...
Journal of Economic Entomology, 2012
The South American tomato pinworm, Tuta absoluta (Meyrick) has been introduced into new geographic areas, including the Mediterranean region, where it has become a serious threat to tomato production. Three greenhouse trials conducted in tomato crops during 2009 and 2010 explored control strategies using the egg-parasitoid Trichogramma achaeae Nagaraja and Nagarkatti compared with chemical control. The effectiveness of the predator Nesidiocoris tenuis (Reuter) was also tested. In greenhouses with early pest infestations (discrete generations), periodic inundative releases (eight releases at a rate of 50 adults/m 2 , twice a week) were necessary to achieve an adequate parasitism level (85.63 Ϯ 5.70%) early in the growing season. However, only one inoculative release (100 adults/m 2) was sufÞcient to achieve a comparatively high parasitism level (91.03 Ϯ 12.58%) under conditions of high pest incidence and overlapping generations. Some intraguild competition was observed between T. achaeae and the predator, N. tenuis. This mirid species is commonly used in Mediterranean greenhouse tomato crops for the control of the sweetpotato whiteßy, Bemisia tabaci (Gennadius). Tomato cultivars were also observed to inßuence the activity of natural enemies, mainly N. tenuis (whose average numbers ranged between 0.17 Ϯ 0.03 and 0.41 Ϯ 0.05 nymphs per leaf depending on the cultivar). This may be because of differences in plant nutrients in different cultivars, which may affect the feeding of omnivorous insects. In contrast, cultivar effects on T. achaeae were less apparent or possibly nonexistent. Nevertheless, there was an indirect effect in as much as T. achaeae was favored in cultivars not liked by N. tenuis.