Aphelinid Parasitoids Research Articles

New records of three parasitoids, Pteroptrix chinensis, Aphytis hispanicus, and Marlattiella prima (Hymenoptera: Aphelinidae) associated with an exotic scale, Lopholeucaspis japonica (Hemiptera: Diaspididae) in Tennessee.

A survey for parasitoids of Lopholeucaspis japonica Cockerell (Hemiptera: Diaspididae), an exotic scale of woody ornamentals, resulted in the discovery of 3 species of aphelinid parasitoid wasps, Pteroptrix chinensis (Howard), Aphytis hispanicus (Mercet), and Marlattiella prima Howard. This serves as the first report of these parasitoids reared from a host in the state of Tennessee, USA. Despite routine pesticide applications in the surveyed nursery and directed treatments of the infested plants to control the scale outbreak, the percentage of parasitized scale in privet and euonymus shrubs averaged 7.0% and 7.9%, respectively. These parasitoids may be useful in the natural or managed control of this pest in the United States, but additional research is needed to understand how these parasitoids contribute to the control of L. japonica in the landscape and how nursery production practices can be modified to promote parasitoid populations.

A Survey in Hawaii for Parasitoids of Citrus Whiteflies (Hemiptera: Aleyrodidae), for Introduction into Greece.

Whitefly species of Aleurocanthus spiniferus (Quaintance) and A. woglumi Ashby (Hemiptera: Aleyrodidae) are serious pests of citrus and other important fruit crops. The problem of citrus has initiated the successful introduction of several natural enemies for biocontrol programs in Hawaii and many other countries. Here, we summarized the history of infestation and biocontrol efforts of the two whiteflies in Hawaii for possible parasitoid importation into Greece. Two Platygasteridae (Amitus hesperidum Silvestri, A. spiniferus (Brethes), and three Aphelinidae (Encarsia clypealis (Silvestri), E. smithi (Silvestri), E. perplexa Huang, and Polaszek) were released in Hawaii for biocontrol of the citrus whiteflies during the period 1974-1999. The aphelinid Cales noacki Howard, purposely released for Aleurothrixus flococcus (Maskell) in 1982, was also reported to attack other whiteflies, including Aleurocanthus species, on citrus. An additional aphelinid parasitoid, Encarsia nipponica Silvestri, native to Japan and China, was accidentally introduced and found to attack both citrus whiteflies on the islands. Since the colonization of introduced parasitoids in infested fields on four Hawaiian Islands, no survey has been conducted to evaluate their potential impact. We conducted two short surveys during September-November 2022 on the islands of Kauai, Hawaii, and Oahu to introduce the dominant parasitoids to Greece for the biocontrol of A. spiniferus. Results showed that the infestation level was very low on Kauai, Hawaii, and Oahu Islands, with a mean infestation level range of 1.4-3.1 on Hawaii and Oahu Islands, mostly on pummelo and sweet orange, with no detection on the island of Kauai. The dominant parasitoid was characterized as Encarsia perplexa, using molecular analysis. Its parasitism rates ranged from 0 to 28% on the island of Hawaii and 11 to 65% on the island of Oahu. Emerged parasitoids have been reared in Greece for evaluation. This was the first field survey of Hawaii since the introduction and release of citrus whitefly natural enemies.

Exotic whiteflies and Conservation Biological Control in Coconut System

Exotic pests upset biotic balance, threaten biodiversity and distort the livelihood security of the nation. In coconut, five exotic whiteflies viz., spiralling whitefly, Aleurodicus dispersus Russell, rugose spiralling whitefly, Aleurodicus rugioperculatus Martin, Bondar’s nesting whitefly, Paraleyrodes bondari Peracchi, non-native nesting whitefly, Paraleyrodes minei Iaccarino and palm whitefly, Aleurotrachelus atratus Hempel were reported from India. Morphological and molecular identification of these invasive whiteflies were established by puparium and (or) adult taxonomy and cytochrome c oxidase subunit 1 (COI) gene, respectively. Co-existence of nesting whiteflies with other exotic whiteflies regulated population explosion and warranted correct diagnosis of whiteflies in coconut system. Weather parameters viz., precipitation, temperature and humidity play an important role in the gradient outbreak of exotic whiteflies. The aphelinid parasitoids (Encarsia guadeloupae Viggiani, Encarsia dispersa Polaszek), predators (Apertochrysa sp., Cybocephalus sp. coccinellids viz., Jauravia pallidula Motschulsky, Serangium parcesetosum Sicard, Cheilomenes sexmaculata (Fabricius) and entomopathogenic fungus Aschersonia sp. reduced the incursion potential by exotic whiteflies. A sooty mould scavenger beetle, Leiochrinus nilgirianus Kaszab (Tenebrionidae: Coleoptera) that devours sooty mould encrusted on palm leaflets during monsoon phase was reported for the first time from Kerala, India. Pesticide holiday approach, conservation biological control using the aphelinid parasitoids, predators and entomopathogenic fungus as well as in situ habitat conservation of L. nilgirianus through crop-habitat diversification strategy subdued the invasive potential of exotic whiteflies in coconut system by 60%-80% gaining economic benefit to the tune of 17.59 billion rupees. Strict quarantine and systematic surveillance are the need of the hour to combat the biosecurity risks entering the country.

Parasitism of the whitefly Bemisia tabaci by aphelinid parasitoids on cassava across five agro-ecological zones of Cameroon

The whitefly Bemisia tabaci (Gennadius) is the vector of cassava mosaic viruses causing cassava viral diseases, which are the most important biotic constraints of cassava production in sub-Saharan Africa (SSA). Presently, B. tabaci management in cassava fields calls for the development of an integrated approach that relies on host plant resistance and biological control. Data on B. tabaci's natural enemies, particularly parasitoids, in Central Africa are limited. Field surveys were conducted from 2015 to 2017 to identify parasitoids associated with B. tabaci in 5 Cameroon agro-ecological zones. Additionally, population dynamics studies were conducted in replicated fields experiments were conducted from 2016 to 2018 to identify cassava genotypes that can best promote B. tabaci parasitism. Two parasitoids, Encarsia sophia (Girault & Dodd) and Encarsia lutea (Masi) were found parasitizing B. tabaci nymphs with higher parasitism by E. lutea compared with E. sophia. The average parasitism rate during the survey was 33.4% for E. lutea and 8.4% for E. Sophia, regardless of AEZ. The highest parasitism rates by E. lutea (48.2% and 24.2% from field trials and surveys, respectively) were observed in the Western Highlands (AEZ 3) while parasitism by E. sophia was less than 12.4%. Four cassava genotypes (I090590, I011797, I090574, and I070593) promoted higher parasitism rates of B. tabaci by E. lutea and E sophia. The contributions of the two parasitoids and their integration with cassava genotypes for the management of B. tabaci in cassava fields are discussed.

Scale Insects (Hemiptera: Coccomorpha) on Jackfruit (Moraceae) in Nayarit, Mexico

AbstractJackfruit, Artocarpus heterophyllus Lam. (Rosales: Moraceae), was only recently introduced into Mexico, and the state of Nayarit has become its main source of production. Information on its management, development, and production in Mexico is scarce. In this study, we identified four species of scale insects on jackfruit belonging to the families Coccidae (one species), Diaspididae (two species), and Pseudococcidae (one species) from Coccomorpha. We found one species of a parasitic wasp (Hymenoptera: Aphelinidae) and two ant species (Hymenoptera: Formicidae) associated with the mango shield scale, Milviscutulus mangiferae (Green) (Coccidae). Three species of aphelinid parasitoids and one coccinellid species (Coleoptera: Coccinellidae) were found attacking the lesser snow scale, Pinnaspis strachani (Cooley) (Diaspididae). The lesser snow scale and the mango shield scale were the most frequent scales insect species encountered in jackfruit orchards in Nayarit. Therefore, attention should be paid to the populations of these two scale insects, as well as to the type of interaction between ants and the mango shield scale, to design more efficient management of these pests.

Invasion and expansion of exotic whiteflies (Hemiptera: Aleyrodidae) in India and their economic importance

Exotic invasive whiteflies (Hemiptera: Aleyrodidae) in India cause direct and indirect yield losses in agriculture, horticulture and forestry crop plants. Around 25 years ago, the spiralling whitefly, Aleurodicus dispersus Russell invaded and established on many host plants including economically important crops in India. Recently, within a span of five years, seven whiteflies invaded India viz., solanum whitefly, Aleurothrixus trachoides (Back) reported to breed on 37 plant species; rugose spiraling whitefly (RSW), Aleurodicus rugioperculatus Martin found breeding on 40 host plants; nesting whiteflies, Paraleyrodes bondari Peracchi on 34 host plants and P. minei Ιaccarino infest about 25 host plants; legume feeding whitefly, Tetraleurodes acaciae (Quaintance) infesting 5 host plants; palm infesting whitefly, Aleurotrachelus atratus Hempel on 4 host plants and woolly whitefly, Aleurothrixus floccosus (Maskell) infesting guava. These invasive species are native to the Neotropical region, mostly from Central America and the Caribbean. Extensive spread along the coastal regions and gardens near the backwater of India is predicted owing to the favorable weather factors and availability of host plants. Species of exotic whiteflies with similar habits co-exist in more or less the same niche and have a similar pattern of growth and development. The intensity of infestation of RSW on coconut, banana and oil palm, the woolly whitefly on guava and the palm infesting whitefly and nesting whiteflies on coconut was severe. The exotic aphelinid parasitoid, Encarsia guadeloupae Viggiani (Hymenoptera: Aphelinidae), a predator Pseudomallada astur (Banks) (Neuroptera: Chrysopidae) and the entomopathogenic fungus, Isaria fumosorosea Wize (Hypocreales: Clavicipitaceae) play a major role in reducing the population of these invasives. The most insidious spread of these species in India is likely mediated by humans through the movement of infested seedlings and plant materials. Extensive surveys revealed that these species spread rapidly in the large geographical region of India mostly through transportation of infested seedlings. This study reports a major expansion of the geographic and host range and the patterns of co-occurrence, damage and economic impact of these exotic species in India and their natural enemies.

Identification of an aphelinid parasitoid on hemispherical scale insect, Saissetia coffeae (Walker, 1852) (Hemiptera: Coccidae) on olive and fig trees, quantification of parasitism rate and potential as biocontrol agent of the insect

Saissetia coffeae (Walker, 1852) is a serious insect pest on olive and fig trees in the Palestinian Territories, it sucks the sap of infested trees and secretes honey dew which interferes with photosynthesis by attracting the sooty mold fungus. The objectives of present research were: firstly, to identify and describe of an indigenous parasitoid on S. coffeae infesting olive and fig trees in the Palestinian Territories; and secondly, to assess the parasitoid’s efficacy against S. coffeae on olive and fig trees. Results indicated that the parasitoid was identified as Coccophagus rusti Compere, 1928 (Hymenoptera: Aphelinidae) and a detailed description of the parasitoid was provided in this respect. The parasitism rate of the parasitoid on S. coffeae varied significantly with the altitude of sampled localities, it ranged from 14.84 – 64.92% at 635 and 82 m above sea level, respectively, on fig trees, and from 12.68 – 47.25% at 635 and 82 m above sea level, respectively, on olive trees. The overall average rate of parasitism was 42.10% and 29.75% on fig and olive trees, respectively. In conclusion, the high rate of parasitism on S. coffeae makes the parasitoid as potential biocontrol agent of the insect on olive and fig trees.

Secondary endosymbiont diversity of Bemisia tabaci and its parasitoids

Cotton whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is one of the most important insect pests worldwide. It is known as a species complex consisting of at least 40 cryptic species. Although there are substantial data regarding species composition, parasitoids and endosymbionts of B. tabaci, data on relationship between the pest, parasitoids and endosymbionts are very restricted. Therefore, in this study, secondary endosymbionts in populations of B. tabaci and their parasitoids collected from Turkey and the USA were determined by PCR-based DNA analysis. Whitefly populations in Turkey represented both Mediterranean (MED) and Middle East-Asia Minor1 (MEAM1) genotypes from single or mixed populations of both genotypes. Arsenophonus, Rickettsia and Wolbachia were found in MED, while Hamiltonella and Rickettsia in MEAM1. Whitefly populations collected from Arizona were all MEAM1 and dually infected with Hamiltonella and Rickettsia. The aphelinid parasitoids Encarsia lutea and Eretmocerus mundus predominated in all Turkish populations. While almost all En. lutea populations were infected with Wolbachia, no endosymbionts were detected in any Er. mundus. Parasitoid species and the pattern of secondary endosymbiont infection in Arizona populations were different with Rickettsia detected only from Encarsia sophia while both Rickettsia and Wolbachia were found in Eretmocerus species. As a result, four secondary endosymbionts, namely, Rickettsia, Hamiltonella, Arsenophonus and Wolbachia, were detected from B.tabaci and its parasitoids. Among them only Wolbachia and Rickettsia were found in both the pest and parasitoids. It is conclude that further studies should be pursued to determine effect of these endosymbionts on biology of the parasitoids and success in biological control of B. tabaci.

Evaluation of a banker plant system for biological control of Bemisia tabaci (Hemiptera: Aleyrodidae) on tomato, using two aphelinid parasitoids under field-cage conditions

ABSTRACTThis study evaluated the potential of two aphelinid parasitoids, Encarsia sophia (Girault & Dodd) and Eretmocerus hayati (Zolnerowich & Rose) to control the sweetpotato whitefly Bemisia tabaci, (Gennadius) using a banker plant system over two consecutive years. The parasitism rates of both parasitoids on a tomato (Solanum lycopersicum L.) crop were determined using melon, Cucumis melo L. (Cucurbitaceae) and castor bean, Ricinus communis L. (Euphorbiaceae), as banker plants, respectively. The emergence rates of Er. hayati and En. sophia parasitoids from parasitised whiteflies on both banker plants exceeded 90% and 85%, respectively, which is 17–20 percentage points higher than that on the pupal card under field cage conditions. Parasitism (%) on banker plants was significantly higher for both parasitoids in the third week after release as compared to adult releases in the first year, reaching 15.2 ± 1.3 and 24.0 ± 1.4% for En. sophia and Er. hayati, respectively. However, no significant difference in parasitism (%) was observed between banker plant and pupal card release treatments in the second year. The combined release of the two parasitoids during the second year clearly showed a continuous increase in parasitism, which was higher than parasitism in the single parasitoid-release treatments by the 4th week after release. Whitefly populations were significantly lower in all parasitoid-release treatments than in the no-release control by 4–6 weeks into the study period in the second year, while no other significant differences were observed between treatments in either year. This study found that both banker plants efficiently supported populations of both parasitoids and improved their emergence compared to the pupal card.

First record of Encarsia formosa Gahan, an aphelinid parasitoid of greenhouse whitefly from India and its dynamics on tomato grown under protected environment

Greenhouse whitefly, Trialeurodes vaporariorum (Westwood) is a key pest of tomato under protected environment in Himachal Pradesh. Recently, an aphelinid parasitoid, Encarsia formosa Gahan was observed to parasitize T. vaporariorum in mid-hill regions of Himachal Pradesh. It seems to be the first record of this aphelinid parasitoid from India. Population buildup of E. formosa was recorded in eight insecticide based greenhouse whitefly management modules comprising soil application of imidacloprid (0.009%) and foliar applications of spiromesifen (0.02%), thiamethoxam (0.01%) and azadirachtin (0.0003%) in tomato grown during summer cropping seasons of 2015 and 2016 under naturally ventilated polyhouse. Parasitization by E. formosa in the plants without treatment varied from 31.8 to 81.2 and 36.8 to 93.6 per cent during 2015 and 2016, respectively. The insecticidal module comprising single soil application of imidacloprid one day after transplanting followed by alternate foliar applications of azadirachtin starting 45 days after transplanting at 10 days interval proved favourable for buildup of E. formosa as compared to other insecticide based greenhouse whitefly management modules during both the seasons. Based on the observations recorded, it was observed that the parasitoid has the potential for inclusion in greenhouse whitefly management programme.

First record of Encarsia formosa Gahan, 1924 (Hymenoptera: Aphelinidae), a parasitoid of the greenhouse whitefly, Trialeurodes vaporariorum (Westwood, 1856) from India

In northwestern Indian Himalayan region, the immature stages of greenhouse whitefly, Trialeurodes vaporariorum (Westwood) were found parasitised by an aphelinid parasitoid. The examination of female adults revealed the identity of the parasitoid as Encarsia formosa Gahan. This seems to be the first record of E. formosa from India. Under protected cultivation, the extent of parasitisation by E. formosa was upto 78%. The parasitoid has a potential for utilisation in management programmes of greenhouse whitefly under protected cultivation in the region.

Recent trends in biological control of scale insects on fruit crops in India

Scale insects are sap feeders, causing threat to the cultivation of several fruit crops. The scale insects can be grouped into two broad categories. The first group belonging to family Diaspidide, comprises many species of armoured scales (hard scales) belonging to the genera. <em>Aonidiella, Aulacaspis, Pseudaulacaspis, Hemiberlesia, Aspidiotus, Chrysomphalus, Pinnaspis, Parlatoria</em> etc. The second category belonging to family Coccidae comprises of the soft scales belonging to the genera Coccus, Puvinaria, <em>Chloropulvinaria, Saisettia, Parasaisettia, Vinsonia, Drephanococcus, Ceroplastes, Ceroplastodes</em>, etc. Scale insects are highly polyphagous, but certain species cause severe damage to specific fruit crops viz. the red scale, <em>Aonidiella aurantii</em> (Maskell) on citrus; latania scale, <em>Hemieberlesia lataniae</em> (Sign.) on grapevine.; white scale, <em>Aulacaspis tubercularis</em> (Newstead) on mango; green shield scale, <em>Pulvinaria psidii</em> (Maskell) on guava, lemon and sapota, <em>Pulvinaria polygonata</em> (Ckll.) on mango; green scale <em>Coccus viridis</em> (Green) on citrus and sapota and <em>Drephanococcus chiton</em> (Green) on ber and guava. Insecticides are not effective due to the presence of protective cover over the scales. On the other hand, scale insects are more amenable for biological control due to their sedentary habit and colonial distribution. Several scale insects are well regulated by the local predators. In nature, green shield scale, <em>Pulvinaria psidii</em> (Maskell) is kept under check by the predator, Australian ladybird beetle <em>Cryptolaemus montouzieri</em> Mulsant on guava, sapota and lemon. The reduction of the mango green shield scale <em>Pulvinaria polygonata</em> was attributed mainly to the action of the predators <em>C. montrouzieri</em> and <em>Spalgis epeus</em> Westwood. The green scale <em>Coccus viridis</em> on acid lime and white scale <em>Aulacaspis tubercularis</em> on mango are well regulated by the coccinellids <em>Chilocorus nigrita</em> (Fab) and <em>C. circumdatus</em> Sch. Local parasitoids are also known to effectively check the populations of the scale insects on different fruit crops. The encyrtid <em>Anicetus ceylonensis</em> How and the pteromalid <em>Cephaleta brunniventris</em> Motsch are responsible for the suppression of wax scale <em>Drephanococcus chiton</em> on ber and guava. The aphelinid parasitoid, <em>Pteroptrix koebeli</em> How. plays a major role in the regulation of the mango scale <em>Aulacaspis tubercularis</em>. On sapota, the aphelinid parasitoid <em>Coccophagus</em> sp. was the dominant natural enemy causing up to 95 % parasitism. <em>Scutellista cyanea</em> Motsch. (Pteromalidiae: Hymenoptera) was able to suppress <em>Parasaissetia nigra</em> (Nietner) on custard apple and pomegranate. In the absence of effective biocontrol agents in nature, parasitoids and predators have to be released in the field for obtaining an effective and quicker suppression of the scale insects. Release of adult <em>C. nigirita</em> was found to be effective in the control of the red scale on citrus in Karnataka, Andhra Pradesh and Punjab. Release of <em>C. infernalis (C.bijugus)</em> Mulsant @ 10-20 beetles/tree once in April-May has also been recommended to reduce Sanjose scale. The white halo fungus, <em>Lecanicillium (Verticillium ) lecanii</em> can be sprayed at 16 x 10<sup>6</sup> spores/ml along with 0.05% of sticking agents in the evening hours at 15 days interval to control the green scale in the hilly areas during cooler months. The biocontrol agents can be integrated with plant origin insecticides as they do not affect the activity of these agents.

Susceptibility of Larvae and Pupae of the Aphid ParasitoidAphelinus abdominalis(Hymenoptera: Aphelinidae) to the Entomopathogenic FungusBeauveria bassiana

The lettuce aphid, Nasonovia ribisnigri (Mosley), is an economically important pest of lettuce worldwide. Recently, the entomopathogenic fungus, Beauveria bassiana strain GHA, and the aphelinid parasitoid, Aphelinus abdominalis Dalman, have been reported to be potential biological control candidates for use against N. ribisnigri . However, no information is available on the interaction between B. bassiana and A. abdominalis when both are applied. This study therefore examined the compatibility of B. bassiana and A. abdominalis in laboratory experiments. Specifically, we assessed the susceptibility of two A. abdominalis developmental stages (larvae and pupae) to two spore concentrations of B. bassiana (high: 1 × 109 and low: 1 × 104 conidia/ml) and a control of 0.01% Tween 80. We found parasitoid larvae to be highly susceptible to infection at the high spore concentration of B. bassiana , as measured by rates of mummy formation (mean ± SE: 14% ± 2.23) and adult emergence (mean ± SE: 10% ± 5.56) compared with the control treatment (mummification: mean ± SE: 79% ± 3.22; adult emergence: mean ± SE: 87% ± 4.40). In contrast, B. bassiana had no effects on parasitoid development when parasitoid larvae were treated with the lower spore concentration or parasitoid pupae were treated with either high or low spore concentrations. This study suggests that it might be possible to combine B. bassiana and A. abdominalis for integrated pest management of N. ribisnigri . As such, the application of B. bassiana should be timed to coincide with the presence of advanced developmental stages of A. abdominalis to protect the parasitoid. Another option would be to delay the release of A. abdominalis after B. bassiana application, when A. abdominalis is no longer susceptible to fungal infection.

Spatial Distribution and Interaction of Eriosoma lanigerum and Aphelinus mali on Apple Under Dry-Temperate Conditions of India

Knowledge of the seasonal abundance and type of spatial distribution of any insect pest is the prerequisite to formulate a reliable sampling programme for that species. Apple woolly aphid, Erosoma lanigerum (Hausmann) (Hemiptera: Aphididae), is one of the most important insect pests of apple throughout the world. The present study was aimed to study the seasonal abundance and spatial distribution of this pest and its specialist parasitoid, Aphelinus mali (Haldeman) (Hymenoptera: Aphelinidae) under dry temperate conditions of Himachal Pradesh, India during 2013 and 2014. Various dispersion indices were calculated to determine the type of spatial distribution and optimum number of samples. E. lanigerum assumed activity in the month of June and remained active till December by following negative binomial distribution during both the years. The aphelinid parasitoid acted in a density dependent manner by coinciding well with its host and also followed negative binomial distribution except at very low densities. Optimum number of samples required for the aphid and the parasitoid varied with the mean density and the desired precision level.

Natural enemy impacts on Bemisia tabaci (MEAM1) dominate plant quality effects in the cotton system

1. Plant quality (bottom‐up effects) and natural enemies (top‐down effects) affect herbivore performance. Furthermore, plant quality can also influence the impact of natural enemies.2. Lower plant quality through reduced irrigation increased the abundance of the cryptic species from the Bemisia tabaci complex [hereafter B. tabaci Middle East Asia Minor 1 (MEAM1)], but not its natural enemies on cotton. It was therefore predicted that lower plant quality would diminish the impact of natural enemies in regulating this herbivore.3. Over three cotton seasons, plant quality was manipulated via differential irrigation and natural enemy abundance with insecticides. Life tables were used to evaluate the impact of these factors on mortality of immature B. tabaci (MEAM1) over nine generations.4. Mortality of B. tabaci (MEAM1) was consistently affected by natural enemies but not by plant quality. This pattern was driven by high levels of sucking predation, which was the primary (key) factor associated with changes in immature mortality across all irrigation and natural enemy treatments. Dislodgement (chewing predation and weather) and parasitism contributed as key factors in some cases. Analyses also showed that elimination of sucking predation and dislodgement would have the greatest effect on overall mortality.5. The top‐down effects of natural enemies had dominant effects on populations of B. tabaci (MEAM1) relative to the bottom‐up effects of plant quality. Effects were primarily due to native generalist arthropod predators and not more host‐specific aphelinid parasitoids. The findings of this study demonstrate the important role of arthropod predators in population suppression and validate the importance of conservation biological control in this system for effective pest control.

Invasion of the Rugose spiralling whitefly, Aleurodicus rugioperculatus Martin (Hemiptera: Aleyrodidae) in Pollachi tract of Tamil Nadu, India

Following the outbreak for the first time in 2016 of a new invasive rugose spiraling whitefly (RSW), Aleurodicus rugioperculatus Martin in Pollachi, Coimbatore district, Western agro climatic zone of Tamil Nadu, India, a 3-grade damage rating scale was developed to categorize the extent of RSW infestation on different host plants when five host plants were recorded as new viz., Areca catechu L., Azadirachta indica A. Juss., Manihot esculenta Crantz., Myristica fragrans (Houtt.) and Parthenium hysterophorus L. Of the diverse array of natural enemy fauna, the aphelinid parasitoid, Encarsia guadeloupae Viggiani was observed to play a major role in bringing down RSW population. Prolonged dry spell during June to September 2016, after deficit rainfall (69 %) coupled with decreased relative humidity seem to favour the spread of the pest in coconut plantations of Pollachi tract of Tamil Nadu, India.

Long term dynamics of aphelinid parasitoids attacking Bemisia tabaci

Aphelinid parasitoids are widely known natural enemies of Bemisia tabaci (Gennadius), a serious pest of agriculture globally. Here we examine pest–parasitoid interactions and dynamics in Arizona cotton from 1996 to 2010, during which a classical biological control program was implemented. Two native species, Eretmocerus eremicus Rose and Zolnerowich and Encarsia meritoria (Gahan) were either largely or completely displaced by exotic Eretmocerus sp. (Ethiopia) and Encarsia sophia (Gahan) in the early 2000s. Further, E. sophia became the dominant parasitoid of B. tabaci in cotton after many years of predominance by native and exotic Eretmocerus. Apparent rates of parasitism were highly variable within and between years and averaged ≈17% overall. In some years there was evidence that B. tabaci populations declined as apparent parasitism increased. Lower pest abundance was associated with higher rates of apparent parasitism over the entire 15-year period but this pattern was not supported by long term life-table based measurements of parasitism. Detailed life table studies within the entire agro-ecosystem will be needed to fully assess the impact of the classical biological control program.

Host stage suitability and impact of Encarsia noyesi (Hymenoptera: Aphelinidae) on the invasive rugose spiraling whitefly, Aleurodicus rugioperculatus (Hemiptera: Aleyrodidae), in Florida

Rugose spiraling whitefly (RSW), Aleurodicus rugioperculatus, is an invasive species that was first detected in the United States as a pest in urban landscapes in Miami Dade County in south Florida in 2009. Subsequently RSW has spread to become a serious nuisance pest on ornamental plants and palms in urban areas across south Florida. In 2012, an aphelinid parasitoid, Encarsia noyesi, was first documented attacking RSW in Miami Dade County, and observations suggest that as this parasitoid has dispersed and become more common, populations of RSW have declined. Greenhouse studies were conducted to evaluate the potential of E. noyesi as a biocontrol agent against RSW. Findings suggest that E. noyesi is an arrhenotokous, autoparasitoid of whiteflies. In clip cage studies, second, third and fourth stage nymphs were parasitized by E. noyesi and supported development of progeny, with significant reductions in whitefly survival. In screen cage studies, parasitism by E. noyesi reduced whitefly survival from 55% in controls to less than 10% in wasp treatment cages, which translated into smaller adult whitefly populations, and reductions in egg production of 89–98%. The wasps caused abrupt declines in whitefly populations, which were maintained at low levels for several generations until monitoring was terminated. Encarsia noyesi appears to be an excellent candidate for use in a biological control program against RSW in Florida, and could match previous successes using aphelinid parasitoids against whiteflies.

The intracellular bacterium Wolbachia uses parasitoid wasps as phoretic vectors for efficient horizontal transmission.

Facultative bacterial endosymbionts are associated with many arthropods and are primarily transmitted vertically from mother to offspring. However, phylogenetic affiliations suggest that horizontal transmission must also occur. Such horizontal transfer can have important biological and agricultural consequences when endosymbionts increase host fitness. So far horizontal transmission is considered rare and has been difficult to document. Here, we use fluorescence in situ hybridization (FISH) and multi locus sequence typing (MLST) to reveal a potentially common pathway of horizontal transmission of endosymbionts via parasitoids of insects. We illustrate that the mouthparts and ovipositors of an aphelinid parasitoid become contaminated with Wolbachia when this wasp feeds on or probes Wolbachia-infected Bemisia tabaci AsiaII7, and non-lethal probing of uninfected B. tabaci AsiaII7 nymphs by parasitoids carrying Wolbachia resulted in newly and stably infected B. tabaci matrilines. After they were exposed to infected whitefly, the parasitoids were able to transmit Wolbachia efficiently for the following 48 h. Whitefly infected with Wolbachia by parasitoids had increased survival and reduced development times. Overall, our study provides evidence for the horizontal transmission of Wolbachia between insect hosts by parasitic wasps, and the enhanced survival and reproductive abilities of insect hosts may adversely affect biological control programs.

Field cage evaluation of interspecific interaction of two aphelinid parasitoids and biocontrol effect on Bemisia tabaci (Hemiptera: Aleyrodidae) Middle East‐Asia Minor 1

AbstractTo explore sustainably effective biological control measures to suppress the super pest Bemisia tabaci (Gennadius) Middle East‐Asia Minor 1 and better understand the biological control effects of single and multiple releases of parasitoids, we evaluated the performance and interaction of two aphelinid parasitoids of B. tabaci, Eretmocerus hayati Zolnerowich & Rose (an exotic primary parasitoid) and Encarsia sophia (Girault & Dodd) (an autoparasitoid, which is controversial in a biological control program). Single species or two species were jointly (1:1 density ratio) released in field cages on cotton in Hebei province, China, in 2010. Results of the field cage experiment showed that all parasitoid release treatments were successful in reducing the densities of the host B. tabaci relative to the control in which no parasitoid was released. The combined release of two parasitoid species showed the highest control effect among the treatments. Different population growth trajectories indicated asymmetric competitive effects of En. sophia on Er. hayati. The densities of Er. hayati were significantly higher in the Er. hayati alone treatment than in the combined release treatment, while densities of En. sophia were lower in the En. sophia alone treatment than in the combined release treatment. Our results demonstrated interspecific competition between autoparasitoid En. sophia and exotic primary parasitoid Er. hayati. However, no evidence indicated that autoparasitoid En. sophia disrupted the host suppression achieved by primary parasitoid Er. hayati. The release of the autoparasitoid together with the primary parasitoid may not influence host suppression in biological control.