Emergence Of Adult Parasitoids Research Articles

Effect of storage conditions on host egg suitability and the reproductive fitness of Oobius agrili (Hymenoptera: Encyrtidae), an egg parasitoid of the invasive emerald ash borer (Agrilus planipennis) (Coleoptera: Buprestidae).

Oobius agrili Zhang and Huang (Hymenoptera: Encyrtidae) is an important egg parasitoid of the emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae). Methods for laboratory-rearing O. agrili have been developed but its mass-production depends on the continuous production and storage of freshly laid EAB eggs as well as diapaused parasitoid progeny (inside parasitized EAB eggs). The purpose of this study was to determine optimal environmental conditions for long-term storage of host eggs as well as diapaused parasitoid progeny. Fresh host eggs and diapaused parasitoid progeny were stored at two low storage temperatures (1.7 and 12.8 °C) and three levels of relative humidity (low ~31%, medium ~74%, and high ~99.9%) for various length of time (15-270 days) and then evaluated for host egg suitability and the reproductive fitness of stored parasitoid progeny. EAB eggs were stored for approximately 30 days without significant reduction of their viability and suitability to O. agrili parasitism at low storage temperatures under high and medium relative humidity. Neither storage temperature or humidity had any significant effects on adult parasitoid emergence for storage durations of up to 270 days. When storage durations were over 120 days, however, both adult parasitoid longevity and fecundity declined approximately 20-30% across all temperature and humidity treatments. Relevance of findings to mass-production and storage of O. agrili for biocontrol is discussed.

The capacity of Trichogramma chilotraeae (Hymenoptera: Trichogrammatidae) to parasitize Spodoptera frugiperda reared with natural diet vs artificial diet vs alternate host

Parasitoids can be mass-produced easily using artificial diets or an alternate host. This research examined Trichogramma chilotreae’s ability to parasitize S. frugiperda (reared on different diets) and Corcyra cephalonica eggs (alternate host). The research was conducted using a completely randomized design. The treatment used is the type of egg (50 eggs of S. frugiperda fed on a natural and artificial diet during the larval stage and 50 eggs of C. cephalonica). These eggs were exposed for 24 hours to one mated female of T. chilotraeae and then reared until the emergence of adult parasitoids. Results show that T. chilotraeae parasitized more S. frugiperda eggs fed on a natural or artificial diet than C. cephalonica eggs. However, the parasitization rate was the same between the three. Similar to the sex ratio of the resulting T. chilotraeae offspring, S. frugiperda eggs fed on a natural diet produced more female offspring than S. frugiperda eggs fed on an artificial diet or on C. cephalonica eggs, indicating that mass rearing of T. chilotraeae can be carried out using a host in the form of S. frugiperda eggs from adult fed on artificial diet during a larval stage or by using C. cephalonica eggs.

Potential fumigant toxicity of essential oils against Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae) and its egg parasitoid Trichogramma evanescens (Hymenoptera: Trichogrammatidae)

Sitotroga cerealella is a serious pest of a wide range of stored cereal grains. An essential element of an integrated pest control approach is the application of plant oils as a substitute for chemical insecticides. This study aimed to investigate the fumigant toxicity of Allium sativum and Mentha piperita essential oils against S. cerealella adult moths and the egg parasitoid Trichogramma evanescens. Gas chromatography–mass spectrometry analyses detected that Diallyl trisulfide (37.97%) and dl-Menthol (47.67%) as main compounds in A. sativum and M. piperita, respectively. The results showed that, A. sativum at 10.0, 5.0, and 2.5 µL/L air resulted in 100% insect mortality after 24 h exposure. The concentrations of 10.0 and 5.0 µL/L air of M. piperita oil resulted in 100 and 96% insect mortality, respectively. The parasitoid adult emergence in the F1 reduced when exposed to LC99 of A. sativum and M. piperita oils by 10.89 and 9.67%, respectively. Also, the parasitism of emerged parasitoid decreased by 9.25 and 5.84% (class I-harmless), respectively. Therefore A. sativum and M. piperita have the potential to be used as bio-fumigant for the management of S. cerealella and can be used alongside the T. evanescens in integrated pest management.

Host-plant related effects on host feeding, parasitism and sex ratio of Neochrysocharis formosa (Westwood) (Hymenoptera, Eulophidae) attacking Liriomyza huidobrensis (Blanchard) (Diptera, Agromyzidae) leafminer

Liriomyza huidobrensis (Blanchard) (Agromyzidae, Diptera) was the most prevalent on crops infested with leafminers in Jordan, as it was recorded on twelve economic vegetable crops. We investigated the plant-mediated effects on the host feeding, egg laying, parasitism and adult emergence of Neochrysocharis formosa (Westwood) (Eulophidae, Hymenoptera) parasitizing L. huidobrensis larvae on seven vegetables. Results showed that the highest percentage of parasitoid feeding on L. huidobrensis larvae was on bean leaves (9.7%). The lowest percentages of parasitoid host-feeding were on the leaves of white-flowered gourd (4.5%) and eggplant (4.3%) plants. For egg laying, N. formosa females significantly preferred potato (57.7% of parasitism) and bean (46.6% of parasitism) plants. The lowest rates of parasitism occurred on eggplant (17%) and white-flowered gourd (22.3%). The full percentage of adult parasitoid emergence was in bean and broad bean. All plant hosts showed a significant superiority in the parasitoids emergence over eggplant (92.9%) and tomato (85.7%). The highest percentages of emerged parasitoid females were on potato (75%) and the lowest percentage was on eggplant (52%).

Influence of host larval weight of Anastrepha ludens on production parameters and quality attributes in the mass rearing of the parasitoid Diachasmimorpha longicaudata

AbstractLarvae of Anastrepha ludens (Loew) (Diptera: Tephritidae) are non‐native hosts of the parasitoid Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae). These hosts appear to be a very good resource for the development of D. longicaudata in a wide range of larval weights. Therefore, the present study aimed to evaluate whether the larval weight of A. ludens influences the emergence and mass‐rearing parameters of D. longicaudata, including the parasitoid's adult attributes and host selection capacity. Three mean larval weights of 29, 25, and 21 mg were considered as high, medium, and low categories for the analysis. The tests included the effect of management of host larvae in the mass rearing of the parasitoids. In addition, evaluations of flight ability, survival, fecundity, and size were carried out in the adults that emerged from the larvae of the various weight categories. There was a direct relationship between host larval weight and parasitoid pupal weight, but there was no relationship with the emergence of adult parasitoids. However, a high percentage of females emerged from heavier larvae. Similarly, although adults that developed in the heaviest larval category were larger, adult quality parameters were not affected. In the evaluations of host selection, the parasitoids oviposited randomly in the larvae from the various weight categories; there was only selection if larvae of different weights were mixed. In addition, superparasitism did not differ between larval weight categories. In the evaluation of competition for hosts in cages under field conditions, larger female parasitoids that developed in the heaviest host larvae landed more frequently on infested fruit, but oviposition was similar between females of different sizes. In conclusion, the larval weight of A. ludens influenced the size of the host puparia and of adults of D. longicaudata, but the emergence and attributes of the developed adults were similar. Therefore, it can be concluded that the low larval weights of A. ludens evaluated in this study are within the range for proper development of D. longicaudata in mass rearing. This allows several options to produce hosts at a lower cost without negatively affecting the quality of parasitoid production.

Ecological aspect of the larval parasitoid Diadegma hiraii (Hymenoptera: Ichneumonidae) as a potential biological control agent of soybean pod borer Leguminivora glycinivorella (Lepidoptera: Tortricidae).

The larval parasitoid Diadegma hiraii (Kusigemati) was evaluated as a potential biological control agent of the soybean pod borer, Leguminivora glycinivorella (Matsumura). The timing of adult emergence after overwintering was ascertained, and land-use factors that enhance population density were analyzed. Host cocoons were collected and exposed to different temperatures and photoperiod regimes. Subsequently, the emergence of parasitoid was monitored. Land-use types were categorized into 4 land-use types (Poaceae, Fabaceae, Brassicaceae, and forest). Adult parasitoid emergence was dependent on temperature, but largely unaffected by photoperiod. The estimated emergence time of parasitoid was 3 months before the occurrence of the host, suggesting that the overwintered generation may lay eggs in alternate hosts. Parasitism rate was positively correlated with the area covered by Poaceae plants within a 500-m radius of the soybean field. Based on the results of the overwintering ecology and landscape analysis, D. hiraii probably completes its life cycle in the agroecosystems. The parasitoid's effectiveness as a biological control agent may be influenced by the arrangement of land-use types in the agroecosystems surrounding soybean fields. However, the pest control provided by D. hiraii is limited because of approximately 30% of parasitism rate. Consequently, a combination of this species and cultural control and/or other biological control agents is suggested for sustainable soybean cultivation.

Effects of different Philosamia ricini (Lepidoptera: Saturniidae) cold storage periods on Ooencyrtus pityocampae and Ooencyrtus kuvanae (Hymenoptera: Encyrtidae) rearing.

Ooencyrtus pityocampae and Ooencyrtus kuvanae are egg parasitoids that are considered potential candidates for the control of different pest species through inundative release. The aim of this study was to assess the effects of different cold-storage periods of Philosamia ricini eggs (host) on the rearing parameters of O. pityocampae and O. kuvanae. Host eggs were stored at 3 °C, and a factorial experiment involving two parasitoid species, nine host storage periods (1, 5, 10, 15, 30, 45, 60, 75 and 90 days) and a control, and two host ages (1 and 2 days) was conducted, with 10 replications including 40-P. ricini eggs each. Adult emergence, development time, longevity, and fecundity were investigated. The parasitoid adult emergence percentage significantly varied with storage duration. These values were lower in O. kuvanae than in O. pityocampae. The development time of O. kuvanae progeny increased in both host age groups except in the 1-day storage period subgroup. However, the development times of the progeny of O. pityocampae reared on one-day-old eggs stored for 5, 10, 60, and 75 days were increased, and the development times of the progeny of O. pityocampae reared on 2-day-old eggs stored for 45 and 90 days were increased. The longevity of the F1 progeny of O. kuvanae was negatively affected by storage time. There was no difference in the longevity of the F1 progeny of O. pityocampae compared to that of the control. Additionally, the fecundities of the F1 progeny of O. pityocampae and O. kuvanae were 54.7 and 47.0 offspring/female, respectively. These results provide useful information for guiding the development of mass rearing methodologies for both parasitoid species.

Anastrepha striata1 Parasitic Wasps in Guava Crops at Fragmented Landscapes of Nayarit, Mexico

Biological control using native parasitoids is a sustainable alternative to control tephritid flies. We tested whether landscape attributes surrounding guava trees might affect incidence of fruit flies and their parasitoids. From July to September 2019, we collected guava fruit at six locations at Nayarit, México. Pupae obtained from the fruit collected were reared in a laboratory until emergence of adult flies and parasitoids. We combined in situ georeferenced information with 2019 SPOT-7 satellite images to characterize the landscape in circular 500-m buffers. Spearman-rank tests were used to analyze correlation between abundance of Anastrepha striata and parasitoids with the proportion of each soil coverage. Mann-Whitney U and Kruskal-Wallis tests were used to evaluate the influence of management intensity with abundance of the fruit fly and parasitoids. We collected 15.7 kg of guava fruit from six localities. Anastrepha striata was at all localities sampled. Infestation of fruit was 9.4%, ranging from 0.5 to 35.2 larvae per kilogram. The four parasitic wasp species attacking A. striata were Doryctobracon areolatus, Trichopria drosophilae, Aceratoneuromyia indica, and Leptopilina boulardi and are new records of interactions in the State of Nayarit. The wasps attacked 7.5% of the fruit fly pupae.

Reproduction of Ooencyrtus submetallicus (Hymenoptera: Encyrtidae) in egg densities of Euschistus heros (Hemiptera: Pentatomidae)

Abstract Knowledge about the ideal host ratio per female parasitoid reared in glass tubes is important for obtaining descendants with better biological quality. The study aimed to evaluate the reproduction of Ooencyrtus submetallicus (Hymenoptera: Encyrtidae) females in egg densities of Euschistus heros (Hemiptera: Pentatomidae) to find the most adequate relationship between parasitoids and hosts aiming at the parasitoid multiplication. The experiment was conducted with E. heros eggs at densities (parasitoid:host) of 1:3, 1:6, 1:9, 1:12, 1:15, or 1:18 with 24 hours of parasitism by O. submetallicus. The parasitoid females and the egg carton were placed in glass tubes and kept in a climate-controlled chamber. The percentage of parasitism was affected by the nonparasitised eggs. The emergence of adult parasitoids, number of parasitised eggs, number of individual parasitoids emerging per egg, the length of the parasitoids’ posterior tibiae, and the parasitoids’ longevity, life cycle, and sex ratio were not affected by the different densities of nonparasitised eggs subjected to treatments. Ooencyrtus submetallicus parasitised and developed in E. heros eggs in all evaluated densities, with 1:6 presenting the best combination of parasitoid and host.

Parasitoids Collected in Poultry Farms in Brazil

The objective of this work is to report the presence of dipteran parasitoids in poultry farms in Brazil. The experiment was carried out in two poultry farms in the Midwest Region in Brazilian territory. The pupae were removed and individualized in glass capsules for the emergence of adult dipterans or parasitoids. The specie Pachycrepoideus vindemmiae (Rondani) (Hymenoptera: Pteromalidae) presented a frequency of 46.4% and showed parasitism of 93.9%. The species Musca domestica (Diptera: Muscidae) presented a frequency of 93.3%. Of the dipterans collected, the most important species was M. domestica for causing public health problems, disturbing people and being a vector of disease-causing agents.

Temperature Impact on Telenomus podisi Emergence in Field Releases of Unprotected and Encapsulated Parasitoid Pupae.

This work aimed to evaluate the influence of temperature on the emergence of Telenomus podisi throughout the soybean development cycle, using encapsulated and unprotected pupae releases, in four different possible locations where pupae can be deposited during release. The trial was carried out in a randomized block design in a 2 × 4 factorial scheme: two parasitoid pupae release strategies (encapsulated and unprotected) × four pupae locations (between soybean lines of planting, bottom third, middle third, or upper third of plant canopy) with 5 replicates. There were no significant interactions between the studied factors. In the vegetative stage (V2 and V9), a smaller percentage of emergence of parasitoid adults was observed between soybean lines of planting (37.1% and 23.4% for V2 and V9 , respectively). The highest maximum temperatures were recorded between the soybean lines, with the greatest variations in maximum and minimum temperatures (55.2°C and 21.3°C) in V2 and (52.8°C and 23.9°C) inV9. In the reproductive stages (R1, R4, and R7), the observed temperatures were lower when compared to those observed in the vegetative stages (V2 and V9), with no difference in the emergence of parasitoid adults, which was above 70% in stage R1 and above 80% in R4 and R7. Regarding the pupae (encapsulated or unprotected), both allowed similar adult emergence. Therefore, it can be concluded that both unprotected and encapsulated pupae can be released, but those releases during the soybean vegetative development stage should be avoided due to the high temperatures to which pupae can be exposed.

Optimization of Trissolcus japonicus cold storage methods for biological control of Halyomorpha halys

Trissolcus japonicus (Ashmead) (Hymenoptera: Scelionidae) has shown promise as a biological control agent for the invasive agricultural and nuisance pest, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae). In addition to the need for laboratory research colonies, the possibility for rearing T. japonicus for classical or augmentative releases necessitates investigation into efficient rearing protocols with control over timing of production. Cold storage is a means to slow insects’ metabolism and cold temperatures can be used to manipulate when and how many parasitoids are available for use. Conditions of cold storage (i.e., temperature and photoperiod), duration of exposure to cold, nutrition, age, and sex of parasitoids can all affect the success of a cold storage regime. We tested how these factors affected mortality, realized fertility of females, sex of progeny, and development time for cold-stored adult and immature T. japonicus using previously frozen H. halys egg masses. Rearing adult T. japonicus at 8, 13, or 18 °C (10:14 h L:D) significantly increased longevity compared to 23 °C (16:8 h L:D); however, for females reared at 8 °C, 10:14 h L:D, we found sublethal effects on realized fertility and sex of their progeny. Adults with access to food survived at greater levels than those without food. We found high mortality of cold-stored immatures in all the ages and cold storage conditions tested. Additionally, differences in T. japonicus emergence from fresh and frozen H. halys eggs was assessed. This work can be used to compare the costs and benefits of cold storage for T. japonicus and will assist forecasting the emergence and sex of adult parasitoids after T. japonicus are cold stored.

Egg Parasitoids of Cabbage Caterpillars in Sri Lanka: A Search for Biocontrol Agents

Purpose : Management of cabbage caterpillar complex through augmentative release of egg parasitoids has been suggested considering the current issues in insecticide application, mainly the effect on human health, non-target effects and environmental pollution. Use of local egg parasitoid species is preferred considering the environmental risk associated with the use of exotic species; therefore, this study was conducted to examine the egg parasitoid guild of cabbage caterpillars in Sri Lanka. Research Method : Field survey was conducted during January 2012 to May 2013 in major cabbage growing areas in the mid-country. Eggs of cabbage caterpillars were collected and reared them until the emergence of host larvae or adult parasitoids. Emerged parasitoids were preserved in 70% ethanol, and prepared the microscopic slides upon the dissection of male genitalia. Parasitoids were identified by using taxonomic keys and Trichogramma literature as per the protocol suggested by Natural History museum, London and the identities were confirmed by the taxonomist in Natural history museum in London. Findings : Trichoplusia ni, Spodoptera litura, Crocidolomia pavonana and Plutella xylostella were found as the members of cabbage caterpillar complex. Two egg parasitoid species: Trichogramma chilonis Ishi and Trichogramma achaeae Nagaraja and Nagarkatti were found attacking eggs of cabbage caterpillars. Trichogramma chilonis has been reported previously in Sri Lanka but Trichogramma achaeae is the first country report. T. chilonis was widely distributed and caused for higher level of parasitism than T. achaeae. The highest level of parasitism (67%) by both species was found in Trichoplusia ni eggs which was significantly different from other species. Level of parasitism of caterpillar eggs was significantly varied between pesticide free fields (16.8%) and conventional fields (13.1%). Research Limitation : The study of behavioral characters of these parasitoids is required to assess the suitability as biocontrol agents; as an initial step for augmentative biocontrol, the locally available egg parasitoids were reported in this study. Originality/ Value : These findings would be contributing Sri Lankan agriculture sector to develop the augmentative biocontrol approach to manage the cabbage caterpillar complex and to produce pesticide residues free crop produce.

Performance of Trichogramma chilonis on different host

The laboratory experiment was conducted during 2017-2018 to study the different biological attributes of Trichogramma chilonis Ishii as influenced by host eggs of different ages. Significantly maximum percent egg parasitization was noticed on eggs of Helicoverpa armigera (Hubner) with 62.39 percent which was at par with the Corcyra cephalonica (Stainton) eggs (60.36 percent). This was followed by Earias vittella Fabricius 46.31 percent. Less parasitized eggs were recorded in Leucinodes orbonalis Guenee (10.35 percent). Age of host eggs significantly affected the parasitization by T. chilonis . The maximum parasitization (58.87 percent) was noticed in fresh eggs i.e. 24 hrs old followed by 48 hrs (44.91 percent) while 72 hrs old eggs were less preferred by T. chilonis and could parasitize only 30.56 percent. Development period for parasitoid ranged between 8.66 to 9.44 days on different host eggs. The highest adult parasitoid longevity (7.22 days) was observed from the parasitized eggs of H. armigera which was at par with C. cephalonic a (7.10 days), E. vittella (6.88 days) and L. orbonalis (6.88 days). However, the different lepidopteran eggs as well as age of host eggs did not show significant differences pertaining to percent adult parasitoid emergence. Fresh host eggs of 24 hrs could produce more female progeny of T. chilonis (54.30 percent) compared to 72 hrs old eggs (42.65 percent). The sex ratio (male: female) of emerging parasitoid progeny was observed highest on 24 hrs old eggs (1:1.55) followed by 48 hrs old eggs (1:1.23) while lowest sex ratio was observed on the eggs of 72 hrs old age (1:0.95). The maximum per day fecundity of T. chiloni s was noticed on the 24 hrs old eggs (6.75) followed by 48 hrs old eggs (4.80). The lowest fecundity (2.05) of T. chilon is was observed on the 72 hrs old eggs, whereas the highest male-female ratio and fecundity was noticed on eggs of E. vittella among different hosts.

Influence of the plant interacting entomopathogenic fungus Beauveria bassiana on parasitoid host choice-behavior, development, and plant defense pathways.

Inoculating plants with entomopathogenic fungi may influence plant nutrient uptake and growth, and herbivore performance. Knowledge is limited concerning the effects of this symbiosis on higher trophic levels. We examined how fungal treatment of faba bean seeds with the entomopathogenic fungus Beauveria bassiana influenced the choice-behavior and development of the aphid parasitoid Aphidius colemani. We also sampled plant material for analysis of changes in expression of genes related to plant defense pathways. While parasitoids were compatible with plants inoculated with B. bassiana initially (66 vs. 65% parasitization on inoculated and control plants, respectively; similar development times of parasitoids: 9.2 days), the emergence of adult parasitoids originating from aphids on fungus treated plants was significantly lower (67 vs. 76%, respectively). We also found that the defense response changed, similar to induced systemic resistance, when plants were treated with B. bassiana, similarly to what has been found for other plant symbiotic microorganisms. These novel findings show that although the application of entomopathogenic fungi to plants can alter the plants’ defense against herbivores, it may also have an impact on beneficial insects, so their function and use should be evaluated on a case-by-case basis.

Field collection of egg parasitoids of Pentatomidae and Scutelleridae in Northwest Italy and their efficacy in parasitizing Halyomorpha halys under laboratory conditions

AbstractThe invasion of Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) has caused severe economic damage in crops in North America and Europe, motivating research to identify its natural enemies, both in native and invaded areas. In its Asian native range, the main natural enemies are egg parasitoids, among which the most effective are Trissolcus japonicus (Ashmead) and Trissolcus mitsukurii (Ashmead) (Hymenoptera: Scelionidae) in China and Japan, respectively. In Europe, biology, host range, and impact of most native scelionid species are not well‐known. The present study aimed to investigate (1) presence and abundance of scelionid species that parasitize native Pentatomidae and Scutelleridae eggs in Northwest Italy, and (2) their ability to develop on H. halys eggs. During 4‐year field surveys, egg masses were collected and reared until bug nymph or adult parasitoid emergence. Then, the obtained scelionid females were tested for their ability to parasitize H. halys eggs in laboratory no‐choice experiments. Egg masses of all collected bug species were parasitized, and Telenomus spp. (Hymenoptera: Scelionidae), Trissolcus belenus (Walker), and Anastatus bifasciatus (Geoffroy) (Hymenoptera: Eupelmidae) were the most common parasitoids. In the laboratory, Trissolcus kozlovi Rjachovskij was the only species to significantly produce offspring from fresh H. halys eggs, whereas all tested Trissolcus species significantly induced host egg abortion (non‐reproductive effects). This study provides knowledge of the parasitoid species associated with native bugs, and represents a starting point to investigate the intricate interactions between native and exotic parasitoids recently found in northern Italy. These egg parasitoids could potentially be effective biocontrol agents of H. halys.

WITHDRAWN

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Variation in Performance and Resistance to Parasitism of Plutella xylostella Populations.

Two major ecological factors determine the fitness of an insect herbivore: the ability to overcome plant resistance strategies (bottom-up effects) and the ability to avoid or resist attack by natural enemies such as predators and parasitoids (top-down effects). In response to differences in selection pressure, variation may exist in host-plant adaptation and immunity against parasitism among populations of an insect herbivore. We investigated the variation in larval performance of six different Plutella xylostella populations originating from four continents when feeding on a native Dutch plant species, Brassica rapa. One of the used populations has successfully switched its host plant, and is now adapted to pea. In addition, we determined the resistance to attack by the endoparasitoid Diadegma semiclausum originating from the Netherlands (where it is also native) and measured parasitoid performance as a proxy for host resistance against parasitism. Pupal mortality, immature development times, and adult biomass of P. xylostella differed significantly across populations when feeding on the same host plant species. In addition, parasitism success differed in terms of parasitoid adult emergence and their biomass, but not their development times. Variation among natural populations of insects should be considered more when studying interactions between plants and insects up the food chain.

SELECTIVITY OF INSECTICIDES TO Encarsia hispida (Hymenoptera: Aphelinidae)

ABSTRACT The use of non-selective insecticides in agricultural production can reduce or eliminate biological agents that regulate insects that are undesirable to humans in production processes. Here, the toxicity of synthetic products on the parasitoid Encarsia hispida was evaluated, the host of which is the whitefly, Bemisia tabaci biotype B, found on cotton plants. The study was carried out using bioassays, in a completely randomized design in a factorial scheme. Pupae and adults of E. hispida were used in the bioassays, which had been sprayed with various chemicals (thiamethoxam, deltamethrin, imidacloprid, and pyriproxyfen) at different concentrations (1.0 g L-1, 1.0 mL L-1, 4.0 mL L-1, and 2.5 mL L-1). The control treatment was distilled water. Chemicals were topically placed in the dorsal region of the tegument of 1 and 3-day old pupae. Then, between 1 and 15-days of emergence of adult parasitoids, residual contact bioassay were used to determine the toxicity of the insecticides. The insecticides thiamethoxam and imidacloprid were harmless to the pupal stage of E. hispida, but were harmful to the adult stage. The insecticides deltamethrin and pyriproxyfen were harmful to both pupal and adult stages of E. hispida.

Occurrence, Seasonal Abundance, and Superparasitism of Ooencyrtus kuvanae (Hymenoptera: Encyrtidae) as an Egg Parasitoid of the Spotted Lanternfly (Lycorma delicatula) in North America

The occurrence of egg parasitoid Ooencyrtus kuvanae (Howard) (Hymenoptera: Encyrtidae) on its new host, the spotted lanternfly (Lycorma delicatula (White) (Hemiptera: Fulgoridae)), was surveyed at 4 study plots in 2016 and 10 additional plots in 2017 in Pennsylvania through field collection and laboratory incubation. O. kuvanae adults were found on L. delicatula egg mass surfaces at two plots (ODSouth and Lutz) in 2016, but at none in 2017. The results of laboratory incubation showed that O. kuvanae adults were only recovered from host eggs collected at plot ODSouth in 2016, with adults emerging between 22 April and 2 May 2016 at 22 ± 1 °C, 40% ± 5% relative humidity (RH), and a 16:8 h photoperiod (light/dark). The overall parasitism at this study plot was 6.0% by egg mass and 1.2% by egg. Two oviposition sites contained parasitized L. delicatula eggs, with 12.3% (9.5–15.0%) host egg masses and 3.1% (1.3–5.0%) host eggs utilized by the parasitoid. O. kuvanae parasitism by egg was significantly higher on oviposition site ODSouth #7 than on ODSouth #8. No O. kuvanae adults were reared out of field-collected host eggs from the 10 plots in 2017. Seasonal abundance and superparasitism of O. kuvanae was examined at plot ODSouth in 2017. O. kuvanae-parasitized L. delicatula eggs were found on all four oviposition sites based on field monitoring of parasitoid adult emergence, resulting in a parasitism of 35.4% (18.8–55.6%) by egg mass and 2.2% (0.5–3.9%) by egg. No significant difference in parasitism by egg was observed among oviposition sites. O. kuvanae adults emerged in the field between 2 May and 1 June 2017. Superparasitism was confirmed for O. kuvanae on L. delicatula eggs based on parasitoid production (1.0–3.3 adults/parasitized egg) and adult exit holes (1–3 exit holes/parasitized egg). As the first parasitoid recorded from L. delicatula in North America, O. kuvanae has the potential to become an important biological control agent for L. delicatula in North America, with its well-synchronized life history in the spring, century-long field establishment, superparasitism, and female-biased progeny population. L. delicatula complements the gypsy moth well as an alternative host for O. kuvanae in the field.