Natural Enemy Complex Research Articles

<b>Parasitoids associated with the black scale <i>Saissetia oleae</i>(Olivier) (Hemiptera: Coccidae) in olive trees in Minas Gerais State, Brazil

Black scale, Saissetia oleae (Olivier) (Hemiptera: Coccidae) is an important pest of olive trees (Olea europaea L.) that requires the use insecticides for its control. Parasitoids are important regulating agents of this pest, but currently, no information on its complex of natural enemies and their impact on black scale in Brazilian conditions exists. This study focused on identifying parasitoid wasps that were associated with the black scale on olive trees to establish their relative abundance and rate of parasitism. Samplings were maintained in an olive orchard located in Maria da Fe, south of the state of Minas Gerais, Brazil, and infested branches were stored in emergence containers to recover parasitoids. Another group was kept in Flanders batteries to evaluate the rate of parasitism in approximately 100 scales. Sixteen parasitoid species were collected during the sampling period, and the most common species were Coccophagus caridei (Brethes) (Hymenoptera: Aphelinidae), Diversinervus elegans Silvestri (Hymenoptera: Encyrtidae), and Mesopeltita truncatipennis (Waterston) (Hymenoptera: Pteromalidae), the latter of which was most abundant and frequent. Parasitism ranged from 3 to 31% with peaks in summer and autumn. This level could be considered insufficient to hold the black scale under the economic injury level; however, these parasitoids should be preserved for contributions to population regulation.

Native Parasitoid Response to Emerald Ash Borer (Coleoptera: Buprestidae) and Ash Decline in Recently Invaded Forests of the Central United States

ABSTRACT Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) is a wood-boring pest of Asian origin that has caused widespread mortality of ash, Fraxinus spp., in North America since its accidental introduction in the 1990s. Studies conducted at the epicenter of the infestation in the Great Lakes region have discovered several species of native parasitoids capable of utilizing A. planipennis; however, little is known of how these natural enemy complexes vary across the shifting forest types and habitats encompassed by the expanding infestation. We characterized the assemblage of native natural enemies being recruited to A. planipennis at five sites in north-central Kentucky, where infestations have been documented since 2009. Through destructive sampling, dissection, and rearing of infested ash material, 12 native parasitoid morpho-species were found being recruited to A. planipennis, nine of which have not been reported previously. Catogenus rufus (F.) (Coleopter: Passandridae), Phasgonophora sulcata ...

Preliminary Observations on Zelus obscuridorsis (Stål) (Hemiptera: Reduviidae) as Predator of the Corn Leafhopper (Hemiptera: Cicadellidae) in Argentina.

The corn leafhopper Dalbulus maidis (Hemiptera: Cicadellidae), is an important corn pest in most of tropical and subtropical America. This leafhopper has a rich natural enemy complex of which parasitoids and pathogens are the most studied; knowledge on its predators is limited. We noted the presence of the native assassin bug Zelus obscuridorsis (Hemiptera: Reduviidae) predating diverse motile insects, including the corn leafhopper, on corn plants cultivated in household vegetable gardens in San Miguel de Tucumán (Argentina); in order to verify its predatory actions, we exposed lab-bred individuals of D. maidis to adults of Z. obscuridorsis. The predators were starved for 24 h before trials in which the corn leafhopper in different developmental stages were exposed. Zelus obscuridorsis is highly skilled in catching specimens in motion, but it was not able to prey on eggs. The predator was capable to catch and prey on nymphs and adults.

Natural enemies of soft scale insects (Hemiptera: Coccoidea: Coccidae) in Australian vineyards

Background and Aims There is increasing interest in using natural enemies to control pests in viticulture, but in Australian vineyards, this is often hampered by a lack of information on enemies of particular pest groups. Here we provide an assessment for the first time of the natural enemies of coccids of grapevines. Methods and Results The main coccid pest, Parthenolecanium persicae, was attacked by the parasitoid Metaphycus maculipennis, which constituted 75% of the parasitoids collected from this species. The second most abundant coccid in Australia vineyards, Parthenolecanium pruinosum, was attacked only by one parasitoid, Coccophagus lycimnia. The most common coccinellid predator was Rhyzobius pulchellus, whereas other coccinellids including Cryptolaemus montrouzieri were less common. Several other coleopteran species as well as the moth Mataeomera dubia and several neuroptera are also likely to be important coccid predators. Conclusions These results point to a complex and much wider range of natural enemies attacking vineyard Coccidae than previously appreciated, although P. pruinosum may have few enemies. Significance of the Study Grapevine scale pests have an array of natural enemies including parasitoids, beetles, moth larvae and lacewings, highlighting the importance of maintaining a diverse insect community in vineyards for biological control.

INSECT PEST COMPLEX OF CASHEW AND INFLUENCE OF BIOTIC AND ABIOTIC FACTORS ON THE INCIDENCE OF CASHEW PESTS IN MAIDAN PARTS OF KARNATAKA

Productivity of cashew (Anacardium occidentale L.) in India is influenced by many biotic and abiotic factors, of which pest damage is one of the main constraints. Tea mosquito bug (TMB), Helopeltis antonii Sign. and cashew stem and root borer (CSRB), Plocaederus ferrugineus L. are the two major pests and the minor pests occur with a regional specificity. Hence the study was taken to ascertain the insect pests infecting cashew, their period of occurrence, pest status and natural enemy complex. Cashew plantations of AICRP, Chintamani and cashew fields of farmers in maidan parts of Karnataka were chosen for the survey. During the course of survey, 37 species of insect pests inflicting mild to severe injury to the cashew crop were noticed. The TMB and CSRB, were the most notorious pests of cashew in maidan parts of Karnataka. During the survey, 3 species of spiders, 1 species of reduviid bug and 1 species of preying mantis were found feeding on different stages of TMB. Aphids were predated by coccinellids, syrphids, brown and green lacewing. The maximum temperature (0.239) and sunshine hours (0.516) had a positive relation with the activity of TMB, but negative correlation was established with morning and evening relative humidity (-0.327 and -0.402) and rainfall (-0.369). The activity of CSRB was observed throughout the year but its activity was low during December and January months. Maximum temperature had positive correlation (0.721) with the incidence of the pest.

Natural Enemy Complex of Some Agroforestry Systems of Aizawl and Their Implications in Insect Pest Management

Agroforestry systems of the hilly regions of the north east are small scale, primitive land use systems, evolving through traditional knowledge requiring very little inputs in terms of irrigation, fertilizers and pesticides. The different components of the agroforestry systems were analyzed for their natural enemy complex through a monthly sampling programme. Maintenance and potential role of natural enemies’ complex in various compartments of such systems are discussed in the light of land use practices and holding size.

Tracing prey origins, proportions and feeding periods for predatory beetles from agricultural systems using carbon and nitrogen stable isotope analyses

Predatory beetles are an important component of the natural enemy complex that preys on insect pests such as aphids within agroecosystems. Tracing diet origins and movement of natural enemies aids understanding their role in the food web and informs strategies for their effective conservation. Field sampling and laboratory experiments were carried out to examine the changes of carbon and nitrogen stable isotope ratios (δ13C and δ15N) among crops (cotton and maize), pests (cotton and maize aphids), and between wing and abdomen of predatory beetles, Propylea japonica, and to test the hypothesis that prey origins, proportions and feeding periods of the predatory beetles can be deduced by this stable isotope analysis. Results showed that the δ13C values both in wing and abdomen of adult P. japonica were changing from a C3- to a C4-based diet of aphids reared on maize or cotton, respectively; the isotope ratio of their new C4 substrates were detectable within 7days and the δ15N values began to reflect their new C4 substrates within 3days. The relationship between δ13C and δ15N values of P. japonica adults in wing or abdomen and diets of aphids from a C3-based resource transitioning to a C4-based resource were described best in linear or quadratic equations. Results suggest that integrative analysis of δ13C and δ15N values can be regarded as a useful method for quantifying to trace prey origins, proportions of diets and feeding periods of natural enemies. The results can provide quantifying techniques for habitat management of natural enemies.

Occurrence of insect-pests infesting cowpea (Vigna unguiculatawalpers) and their natural enemy complex in associations with weather variables

The field experiment was carried out during cropping seasons of zaid, 2009-10 and 2010-11. The experimental field was regularly monitored at weekly interval and revealed that eight insects namely jassid, pod bug, leaf miner, whitefly, thrips, legume pod borer, lady bird beetles (predator) and spiders (predator) appeared on cowpea. The incidence patterns of these insects were almost similar with slight fluctuations during both cropping seasons. The correlation and regression coefficients showed both positive and negative relationships of insect-pests infesting cowpea and their natural enemies with existing weather variables.

Incorporating natural enemy units into a dynamic action threshold for the soybean aphid,Aphis glycines(Homoptera: Aphididae)

Recommended action thresholds for soybean aphid, Aphis glycines, do not adjust for natural enemy impact, although natural enemies contribute important biological control services. Because individual natural enemy species have varied impacts on pest population dynamics, incorporating the impact of a diverse predator guild into an action threshold can be cumbersome. Field surveys identified an aphidophagous natural enemy complex dominated by Orius insidiosus, Coccinella septempunctata, Harmonia axyridis and Aphelinus certus. Functional responses of O. insidiosus were determined in the laboratory, while predation rates of all other natural enemies were obtained from the literature. Natural enemy impacts were normalized using natural enemy units (NEUs), where 1 NEU = 100 aphids consumed or parasitized. A dynamic action threshold (DAT) was developed by combining NEUs with an A. glycines population growth model. With the DAT, an insecticide application was only triggered if natural enemy numbers were insufficient to suppress pest populations. In field experiments, DAT provided equivalent yields to the conventional action threshold and reduced the average number of pesticide applications. The DAT approach has the potential to reduce pesticide use, will help preserve natural enemy populations and can be applied to other pest systems with diverse natural enemy guilds.

Natural Enemy Complex Associated with the Mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) Infesting Different Host Plants in India

Recently, Indian cotton belt experienced a devastating outbreak of Phenacoccus solenopsis Tinsley. Natural enemy complex associated with P. solenopsis was explored by conducting extensive field surveys coupled with laboratory screening of samples collected from various localities across the country. A total of seventeen parasitoids inclusive of hyperparasitoids were identified. An encyrtid, Aenasius bambawalei Hayat, was found predominantly on P. solenopsis . Promuscidea unfasciativentris Girault predominated the hyperparasitic fauna. Interestingly, Aphanogmus sp. and Anastatus sp. were recorded for the first time on P. solenopsis . Additionally, eight species of Coccinellidae and two species of Chrysopidae were recovered as important predators.

A mechanistic model for a tritrophic interaction involving soybean aphid, its host plants, and multiple natural enemies

Soybean aphid (Aphis glycines) is a severe pest of soybean in North America with a diverse natural enemy guild. A large body of literature exists examining aspects of the biology and ecology of this species, but these studies have not been synthesized in a quantitative context, limiting the understanding of the relative importance of environmental and ecological factors in the population dynamics of this species. Existing models for population dynamics of A. glycines are geographically restricted, and do not incorporate host plant phenology or natural enemy impact on aphid population dynamics and phenology. In this paper, a mechanistic tritrophic population and phenology model is developed for this species, incorporating environmental cues, host plant cues and natural enemy dynamics. Individual natural enemy species differ with respect to prey consumption rates and foraging behaviours and may occur at different times in the lifecycle of a prey species in response to environmental cues, densities, or the availability of alternate prey. Additionally, the natural enemy complex of A. glycines differs in composition and abundance in different parts of the aphids range. Because of these factors, we developed a strategy to quantify impact of the natural enemy guild that would facilitate the incorporation of natural enemy complexes occurring at multiple locations. In order to standardize the impact of natural enemy guilds on prey species, we used the Natural Enemy Unit (NEU), where NEU is defined as the number of individuals of a predatory species that can kill 100 individual prey in 24h. After calibration of the NEU calculation to incorporate a type III functional response to prevent natural enemies from driving aphid populations to local extinction, the model performed very well in predicting the dynamics between populations of natural enemies and A. glycines when compared to field observations. Simulations suggest that natural enemy abundance impacts A. glycines abundance more strongly than environmental conditions, but host plant phenology also dramatically influences dynamics of this species.

Could Brassica rapa, Brassica juncea and Sinapis alba facilitate the control of the cabbage seed weevil in oilseed rape crops?

A two-year small plot experiment was performed to test whether (1) other plants in the cruciferous family: Brassica juncea (L.) Czern. and Sinapis alba L. are more attractive to the cabbage seed weevil (Ceutorhynchus obstrictus (Marsham)) than turnip rape (Brassica rapa Metzg.) and oilseed rape (Brassica napus L.); (2) the host plant species affects the oviposition preferences of parasitoid species attacking the cabbage seed weevil. According to our results oilseed rape had the highest pest infestation. The parasitism rate was highest on B. juncea and B. rapa. Thus, we can assume that wild relatives of oilseed rape plants can support the presence of hymenopteran natural enemies of pests in the field. The parasitism rate was surprisingly high, up to 85.4% on B. juncea. In addition to the key parasitoids of C. obstrictus, species from the family Mymaridae were also found. The species composition of parasitoids differed between investigated plant species, suggesting that the physical or volatile characteristics of closely related plant species affect the behavioural responses of C. obstrictus parasitoids and therefore could be used to enhance the natural enemy complex.

Dreyfusia nordmannianae in Northern and Central Europe: potential for biological control and comments on its taxonomy

AbstractThe silver fir woolly adelgid, Dreyfusia nordmannianae, is the most severe pest occurring on Abies nordmanniana in Central and Northern Europe. The adelgid is particularly damaging to trees in Christmas tree plantations. Dreyfusia nordmannianae is native to the Caucasus region and alien to Europe, where its natural enemy complex is less diverse compared to its area of origin. Mitochondrial and nuclear DNA sequence data from the samples of D. nordmannianae collected in its native range and Europe and from the samples of Dreyfusia piceae and Dreyfusia prelli collected in Europe and North America were examined for phylogenetic structure. There was no evidence of differentiation, suggesting that these Dreyfusia species have recently diverged or require taxonomic revision. All existing published and unpublished reports on natural enemies of D. nordmannianae in its place of origin were reviewed, with the purpose of selecting agents for classical biological control in Europe. The literature review suggested that the most promising agent was the Chamaemyiidae fly, Leucopis hennigrata. A new survey in D. nordmannianae's area of origin – Turkey, Georgia and Russia – showed that L. hennigrata was present in all localities. It was particularly abundant in Turkey, where its impact on populations of D. nordmannianae appears to be high. Its use as a biological control agent is discussed, as well as other biological control strategies.

Fortuitous biological control of the invasive mealybug Phenacoccus peruvianus in Southern Europe

Phenacoccus peruvianus Granara de Willink (Hemiptera: Pseudococcidae) is a Neotropical invasive mealybug that has rapidly spread throughout Mediterranean Basin. It has established itself as the principal pest of several ornamental plants, causing considerable problems in nurseries and urban landscapes. The aim of this study was to determine the natural enemy complex of this pest and report the feasibility of its biological control. Six urban green spaces were surveyed in eastern Spain from 2008 to 2010. The most abundant natural enemies of P. peruvianus were found to be the primary parasitoids Acerophagus n. sp. near coccois and Leptomastix epona Walker (Hymenoptera: Encyrtidae). Phenacoccus peruvianus populations were lower during the second and third year of the survey, coinciding with an increase of the parasitoid Acerophagus sp., which displaced the native L. epona. Differential female offspring and resource preemption are discussed as the main reasons for this displacement.

Fire Ants (Solenopsisspp.) and Their Natural Enemies in Southern South America

We review the fire ant research conducted by the ARS-South American Biological Control Laboratory (SABCL) since 1987 to find a complex of natural enemies in southern South America and evaluate their specificity and suitability for field release as self-sustaining biological control agents. We also include those studies conducted by the ARS-Center for Medical, Agriculture, and Veterinary Entomology in the United States with the SABCL collaboration. Ecological and biological information is reported on local fire ants and their microsporidia, nematodes, viruses, phorid flies, eucharitid wasps, strepsiptera, and parasitic ants. Their biology, abundance, distribution, detrimental effect, field persistence, specificity, and phenology are discussed. We conclude that the objectives of the ARS program in South America are being achieved and that the pioneering studies have served to encourage further investigations in the United States and other countries and advanced the implementation of biological control programs to decrease imported fire ant densities and damage. Still, several promising organisms should be further investigated for eventual field release in the near future.

Role of molecular genetics in identifying ‘fine tuned’ natural enemies of the invasive Brazilian peppertree, Schinus terebinthifolius: a review

Brazilian peppertree, Schinus terebinthifolius Raddi (Sapindales: Anacardiaceae), is a highly successful invasive species in the continental United States, Hawaiian archipelago, several Caribbean Islands, Australia, Bermuda, and a number of other countries worldwide. It also is one of only a few invasive intraspecific hybrids that has been well characterized genetically. The natural enemy complex of Brazilian peppertree includes two thrips and two psyllids that appear to be highly adapted to specific haplotypes or their hybrids. Successful biological control of Brazilian peppertree will require careful matching of the appropriate natural enemies with their host plant genotypes. The Brazilian peppertree model reviewed here could provide a useful framework for studying biological control agents on other invasive weed species that have exhibited intraspecific hybridization.

BIOLOGICAL CONTROL OF APHIDS BY THE PREDATORY MIDGE APHIDOLETES APHIDIMYZA IN THE PRESENCE OF INTRAGUILD PREDATORY BUGS AND THRIPS

BIOLOGICAL CONTROL OF APHIDS BY THE PREDATORY MIDGE APHIDOLETES APHIDIMYZA IN THE PRESENCE OF INTRAGUILD PREDATORY BUGS AND THRIPS

A review of the natural enemies of the red palm mite, Raoiella indica (Acari: Tenuipalpidae)

A review of all the available information about the natural enemies reported in association with the red palm mite, Raoiella indica is presented. Twenty-eight species of predatory arthropods, including mites and insects, have been reported in association with R. indica in Asia, Africa and the Neotropics. In addition, pathogenic fungi associated with R. indica in the Caribbean have been reported. The available literature indicates that each site has a different natural enemy complex with only one predator species, Amblyseius largoensis (Acari: Phytoseiidae), present in all the geographical areas. The phytoseiids, Amblyseius caudatus Berlese, Amblyseius channabasavanni Gupta and A. largoensis, were regarded as important natural enemies of R. indica, and their predatory efficiency was studied in some detail. Among the predatory insects the coccinellids Stethorus keralicus Kapur and Telsimia ephippiger Chapin were reported as major predators of R. indica. The known distribution, abundance and relative importance of each species reported in association with R. indica are discussed.

Phenology and impact of natural enemies associated with the hop looper (Hypena humuli) in Washington State, USA

The hop looper, Hypena humuli Harris (Lepidoptera: Noctuidae), is becoming an increasingly important pest of hops (Humulus lupulus L.) (Rosales: Cannabaceae) in western USA. Currently, control of this pest usually involves broad-spectrum pesticides that kill natural enemies and disrupt biological control of other hop pests. In order to develop better management strategies for H. humuli, field and laboratory studies were conducted over a four-year period to identify the pest's natural enemies and to investigate their phenologies and to assess their impact. Nine parasitoid species and assorted species of invertebrate predator were found to attack different life-stages of H. humuli. Levels of parasitism were consistently low throughout the study period and none of the parasitoids found was a specialist natural enemy of the pests. Exclusion cage studies showed, however, that the complex of natural enemies as a whole can significantly reduce larval densities of the pest, and laboratory studies confirmed successful predation of H. humuli larvae by several generalist predators including the European earwig (Forficula auricularia L.), the damsel bug Nabis alternatus Parshley and two species of the geocorid bug genus Geocoris.

Enhancing predation of a subterranean insect pest: A conservation benefit of winter vegetation in agroecosystems

Generalist predator communities are abundant and diverse in agroecosystems, but pests often persist nevertheless. Winter vegetation (e.g., cover crops) provides an agronomically sound opportunity to conserve predator communities and promote their impact on pests. We evaluate whether winter vegetation increases predation of Diabrotica virgifera, a key subterranean pest of maize. Fields of maize were preceded by a winter cover crop (slender wheatgrass) or a fallow period (bare soil) over two years. Pest populations and root damage were measured in each field, from which the gut contents of predators aspirated from the soil surface, or extracted from the soil column, were analyzed using qPCR and primer sets specific to D. virgifera COI gene sequences. Predation intensity on restrained D. virgifera larvae (sentinels) was observed during the three larval stadia of the pest ( n = 400 3rd instars per plot per stadium). A diverse predator community consumed D. virgifera in maize fields, and predation was significantly greater in maize following cover crops (as measured with sentinels, but not gut content analysis). Predation was particularly intense during the 3rd stadium of the pest, especially in the cover-cropped maize. qPCR-based gut content analysis of natural populations functioned well in determining which predators consumed D. virgifera, but was only correlated with their impact on the pest and its damage when the relative frequency of detection, quantity of DNA calculated, and predator abundance were combined into a predation index. In support of these observations, predation intensity on sentinels was negatively correlated with D. virgifera populations and plant damage, but did not provide an accurate picture of the community involved. Cover crops reduced D. virgifera populations by increasing predation levels on this pest, which indicates that conserving predation as an ecosystem service is a mechanism for how this form of habitat diversification functions. Also, we conclude that employing diverse methods provides the best insight into trophic relationships within subterranean systems. Finally, because of the dynamic and diverse interactions between pests and their natural enemy complexes, we advocate conserving diverse predator communities within agroecosystems, rather than targeting conservation efforts at specific key predator taxa.