Species For Biological Control Research Articles

Compatibility of aphid resistance in soybean and biological control by the parasitoid Aphidius colemani (Hymenoptera: Braconidae)

Biological control and soybean cultivars bred for increased resistance to the soybean aphid (Aphis glycines) are two approaches used to manage this serious pest of soybeans in North America. However, as with many other pest systems, the compatibility of these two pest management approaches has not been studied in detail. The aphidiine wasp Aphidius colemani is one of several candidate species for biological control of the soybean aphid in soybean in North America. Resistance to the soybean aphid in the USDA soybean cultivar Dowling is largely controlled by a single dominant gene Rag1, which is the focus of plant breeding programs directed against the soybean aphid. In this study, we measured developmental and behavioral differences in the parasitic wasp A. colemani when it attacked soybean aphids feeding on either the aphid-resistant Dowling or aphid-susceptible Glenwood cultivars of soybean. We used a combination of choice and no-choice experiments to examine the effects of host plant cultivar on the number of parasitized aphids formed and the sex ratio and body weights of adult offspring produced. Significantly more aphids were parasitized when they fed on Glenwood compared to Dowling and these offspring were larger when they developed in aphids that fed on Glenwood soybeans. To distinguish between effects on foraging decisions and offspring survivorship, we conducted an additional experiment that followed the oviposition decisions and fate of each parasitized aphid. Foraging female A. colemani spent less time handling individual aphids and encountered and attacked aphids at a higher rate when they fed on aphids feeding on Glenwood soybeans than aphids feeding on Dowling soybeans. Furthermore, wasp survivorship in aphids was greater on Glenwood than Dowling. Taken together, aphid-resistance in soybeans has negative effects on foraging behavior and offspring fitness of A. colemani raising concerns about the compatibility of these two pest management approaches.

Biological characteristics of Telenomus alecto and Trichogramma galloi reared on eggs of the sugarcane borer Diatraea flavipennella

Diatraea flavipennella (Box) (Lepidoptera, Crambidae) is one of the most destructive pests in sugarcane plantations in the Northeast Region of Brazil. Developmental characteristics and parasitism potential of the egg parasitoids Telenomus alecto Crawford (Hymenoptera, Scelionidae) and Trichogramma galloi Zucchi (Hymenoptera, Trichogrammatidae) were compared with the aim of selecting a suitable species for biological control of D. flavipennella. Both T. alecto and T. galloi developed well and were readily adapted to D. flavipennella eggs as host. Although, T. galloi presented higher viability, with more adults emerging per host egg and higher sex ratio, the developmental period (egg-adult) was shorter in T. alecto and female longevity was extended. In addition, T. alecto exhibited significant higher levels of parasitism during the first three days after emergence than T. galloi. Thus, both parasitoids studied here offer considerable potential for the control of D. flavipennella in sugarcane.

The conceptual and practical implications of interpreting diet breadth mechanistically in generalist predatory insects

The concept of ecological generalism (or polyphagy) is widely used in ecology to describe and predict aspects of the behaviour of predatory insects, notably with regard to the management of insect pests. The assumptions of ecological generalism have their basis in competition and optimization. We review the historical context and perspectives that led to the development of the concept of ecological generalism as it is applied to diet breadth in predatory insects. We identify how flaws in this concept limit its utility in describing and predicting the behaviour of organisms. We re-analyse the behavioural expectations of putatively generalist organisms with a focus on the mechanistic aspects of predation; that is, we develop an interpretation based on the adaptations that mediate their responses to particular cues in their environment. This mechanistic analysis emphasizes the need to determine the primary environmental associations of putatively generalist species, and the adaptations that underpin those associations. This approach thus highlights the importance of appropriate matching of predator species to prey species in biological control, based on an understanding of these adaptations and associations.

Multiparasitism by Tetrastichus planipennisi (Hymenoptera: Eulophidae) and Spathius agrili (Hymenoptera: Braconidae): Implication for biological control of the emerald ash borer (Coleoptera: Buprestidae)

Interspecific competition among different species of insect parasitoids may affect the establishment or efficacy of these species in biological control of targeted pests. The endoparasitoid Tetrastichus planipennisi Yang and the ectoparasitoid Spathius agrili Yang, two gregarious larval parasitoids native to China, have recently been introduced to the United States for biological control of emerald ash borer (EAB), Agrilus planipennis Fairmaire. The potential competition between these two parasitoids via multiparasitism of the same host larva was examined in the laboratory. In dual-choice assays where healthy EAB larvae were presented along with those already parasitized by S. agrili at different times, T. planipennisi attacked hosts parasitized by S. agrili for up to 2days, but not 4days. Compared to healthy EAB larvae, the parasitism rate was not significantly different in the hosts previously parasitized for 0days, but decreased significantly in those for 2days. This indicates that the ability of T. planipennisi to discriminate host larvae parasitized by S. agrili increased significantly 2days after the host larvae were parasitized by S. agrili. Additional observations showed that a majority (>91%) of EAB larvae parasitized by S. agrili were completely paralyzed 2days after the attack, indicating that paralysis of host larvae by S. agrili allows T. planipennisi to discriminate between healthy and previously parasitized larvae. In no-choice assays where T. planipennisi females were presented either with healthy EAB larvae or EAB larvae exposed to S. agrili at 0, 2 and 4days earlier, T. planipennisi parasitized significantly more healthy EAB larvae than S. agrili-parasitized larvae in all the exposure times. In addition, the subsequent exposure to T. planipennisi did not affect either parasitism rates by or progeny production of S. agrili, irrespective of the duration between S. agrili and T. planipennisi exposures. These results suggest that competitive interactions between these parasitoids would be of limited importance on the biological control program if these species were released against EAB at the same time and place.

Parasitismo oófago de Traça-do-Tomateiro por Trichograma Evanescens (Hymenoptera: Trichogrammatidae)

Tuta absoluta eggs were evaluated as host for Trichogramma evanescens with the aim of using indigenous species for biological control of the South American tomato moth. After being proved that T. evanescens could parasitize and achieve the complete development inside this host, parasitism rate, proportion of eggs within the parasitoid that reach the adult stage and viability of development rate, at three different temperatures (22.0oC, 24.0oC and 25.5oC) were evaluated. Parasitism rate and the proportion of eggs with emerging hole were calculated as number of parasitized eggs and number of eggs with emerging holes, respectively, by the number of viable eggs. The viability of parasitoid development until adult stage was calculated as number of eggs with emerging hole/number of parasitized eggs. T. evanescens parasitized T. absoluta eggs at all the studied temperatures. Parasitism rate and proportion of eggs with emerging holes were higher at 22.0oC; viability of development till adult was higher at 24.0oC.

Lepidopterans as Potential Agents for the Biological Control of the Invasive Plant,Miconia calvescens

This work investigated eight species of Lepidoptera associated with Miconia calvescens DC. (Myrtales: Melastomataceae) in Brazil, including six defoliators, Salbia lotanalis Druce (Lepidoptera: Pyralidae), Druentia inscita Schaus (Mimallonidae), Antiblemma leucocyma Hampson (Noctuidae), three Limacodidae species, a fruit borer Carposina cardinata Meyrick (Carposinidae), and a damager of flowers Pleuroprucha rudimentaria Guenée (Geometridae). Based on host specificity and the damage caused to plants, S. lotanalis and D. inscita are the most promising species for biological control of M. calvescens. Furthermore, if C. cardinata and P. rudimentaria have host specificity in future tests, these caterpillars could also be considered as appropriate biocontrol agents.

Ecology and Management of Sheoak (Casuarina spp.), an Invader of Coastal Florida, U.S.A.

The Casuarina spp. are invasive plants in Florida that threaten biological diversity and beach integrity of coastal habitats. The trees include three species and their hybrids that aggressively invade riverine and coastal areas. Of the three species, C. equisetifolia and C. glauca are highly salt tolerant and widespread in coastal areas. The third species, C. cunninghamiana, invades riverine habitats. These species pose dangers to both the environment and public safety. The environmental damage includes interfering with nesting by endangered sea turtles, American crocodiles, and the rare swallow-tailed kite. Additionally, allelochemical leachates reduce germination and establishment of native vegetation. Casuarina-infested beaches are more prone to sand loss and erosion. Moreover, with shallow roots and tall canopies, they are among the first trees to fall in high winds and as such restrict evacuation efforts during hurricanes. Control of these species is mostly with herbicides, requiring repeated applications and monitoring. One of the most cost-effective means of controlling these invasive species would be with classical biological control. Australian surveys for potential biological control agents began in 2004, resulting in the discovery of several promising candidates. These include seed-feeding torymid wasps, defoliating caterpillars and weevils, leaf tip gall-formers from cecidomyiid midges, and sap-feeding psyllids. Continued work is needed to determine the suitability of these species for biological control. Despite conflicts of interest expressed by some homeowners and the agricultural industry who value the trees for shade and windbreaks, there are good prospects for safe and effective biological control of these invasive species.

Taxonomic review of the genus Orius (Heteroptera: Anthocoridae) in the Korean Peninsula

A total of five species the genus Orius are revised from the Korean Peninsula, containing four native species, O. minutus (Linnaeus 1758), O. sauteri (Poppius 1909), O. nagaii Yasunaga 1993 and O. strigicollis (Poppius 1914), and an introduced species for biological control, O. laevigatus Fieber 1860 . Orius laticollis Reuter 1884, formally recorded in the Korean Peninsula, is deleted from the Korean fauna registry . The preparation of the macerated slide specimen was applied to this group for the first time, which is confirmed to be effective to identify the Orius species, especially the female specimens whose genital structures have been hardly observed in the traditional dissection method. Observing macerated specimens, new taxonomical characters are documented.

Taxon-specific multiplex-PCR for quick, easy, and accurate identification of encyrtid and aphelinid parasitoid species attacking soft scale insects in California citrus groves

Citricola scale, Coccus pseudomagnoliarum Kuwana (Hemiptera: Coccidae), is a serious pest of citrus in California’s San Joaquin Valley, but not in southern California where a complex of Metaphycus spp. Mercet (Hymenoptera: Encyrtidae) suppress it. This has created interest in using these (and other Metaphycus) species for biological control in the San Joaquin Valley. A critical step in assessing an organism’s potential for biological control is the ability to accurately identify it. For Metaphycus spp., this currently requires slide mounted adult specimens and expert taxonomic knowledge. We present a simple, quick and accurate method to identify any life stage of the ten major parasitoids of soft scales in California citrus, based on amplification of ribosomal DNA, using the polymerase chain reaction (PCR). Three multiplex-PCR protocols amplify products of taxon-specific sizes, allowing direct diagnosis of taxa accommodated by the PCR, and reducing identification time to a fraction of that of existing methods.

The effects of different temperatures and relative humidity on the development, mortality and nymphal predation of Anthocoris minki

Mass rearing techniques are a necessity in developing a suitable and economic biological control method. Anthocoris minki Dohrn (Heteroptera: Anthocoridae), which is successfully reared for use in biological control, is a promising indigenous Anthocoris species for biological control of Agonoscena pistaciae Burckhardt and Lauterer (Homoptera: Psyllidae) in pistachio orchards. Development time of nymphal instars, mortality percentage and prey consumption of A. minki fed on Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs were studied at three constant temperatures (20, 25 and 30 ± 1°C) and two relative humidity levels (40 and 65 ± 5%) under laboratory conditions. Temperature and r.h. significantly affected development time and nymphal prey consumption of A. minki. Duration of incubation and total nymphal development time decreased significantly with each increase in temperature. Total nymphal development time of A. minki at 40% and 65% r.h. was 18.6 and 18.6 days at 20°C; 13.7 and 14.6 days at 25°C; and 10.8 and 11.8 days at 30°C, respectively. The shortest nymphal development time and highest nymphal mortality percentage were recorded at 30°C and 40% r.h. The lowest nymphal mortality was 30.1% and 32.1% at 40% and 65% r.h., respectively, at 25°C; the highest nymphal mortality was 51.5% and 52.1% at 20° and 30°C, respectively, and 40% r.h. The highest average number of E. kuehniella eggs consumed was 123.1 at 20°C and 65% r.h., and the lowest was 86.4 at 30°C and 40% r.h. during nymphal development time of A. minki.

Survival of Larvivorous Fish Used for Biological Control of <I>Aedes aegypti</I> Larvae in Domestic Containers With Different Chlorine Concentrations

The two fish species Betta splendens (Regan) and Poecilia reticulata (Peters) are known predators of Aedes aegypti (L., 1762) larvae. Both species have been used for biological control in northeastern Brazil. However, the feasibility of these fish for the control of Ae. aegypti larvae in domestic containers may be limited by their survival in chlorinated water, as supplied by the public water system. We exposed fish to three different concentrations of chlorine: 1, 1.5, and 2.0 mg/liter. All B. splendens survived at 1.0 mg/liter chlorine concentration; 72.5 and 39.3% of B. splendens survived chlorine concentrations of 1.5 and 2.0 mg/liter, respectively. In contrast, only 4.4% of P. reticulata survived at a chlorine concentration of 1.0 mg/liter. We conclude that B. splendens may be an appropriate species for biological control of Ae. aegypti in domestic water tanks.

Parasitoids of cereal leaf beetle, Oulema gallaeciana (Heyden, 1879)

Cereal leaf beetles are serious animal pests of crops in many areas of western and eastern Slovakia. Research was carried out in these areas in order to receive knowledge on occurrence of natural enemies of <I>Oulema gallaeciana</I>. We were detecting particular species of parasitoids parasitising <I>Oulema gallaeciana</I> and their spreading in particular area. The results showed that dominant parasitoid was <I>Necremnus leucarthros</I>. Other parasitoids with bigger proportion on parasitisation were<I> Pteromalus vibulenus</I> and <I>Diplazon</I> spp. with parasitisation up to 30%. In respect of significant parasitisation of <I>Oulema gallaeciana</I> by parasitoid <I>Necremnus leucarthros</I>, it would be appropriate to use this species for biological control of cereal leaf beetle.

Effects of Parent Age at Mating on Reproductive Response of <I>Glyptapanteles flavicoxis</I> (Hymenoptera: Braconidae), a Larval Parasitoid of the Gypsy Moth (Lepidoptera: Lymantriidae)

Glyptapanteles flavicoxis (Marsh) (Hymenoptera: Braconidae) is a gregarious larval parasitoid of the Indian gypsy moth Lymantria obfuscata (Walker) (Lepidoptera: Lymantriidae), that is believed to have potential for inundative releases against gypsy moth populations, because it can be reared in large numbers with few hosts. Unfortunately, sex ratios in laboratory reared G. flavicoxis are usually male-biased, hindering efforts to mass release this species for biological control by making the production of females costly. Because parental age at time of mating is known to affect the sex ratio in some Braconidae, we crossed haploid males and virgin females at 0, 1, 4, 9, and 16 d old with at least 10 trials for each of the 25 combinations. Numbers and sex ratios of progeny produced by females each day were recorded. Both progeny and sex ratios (percentage of females) among progeny produced by ovipositing females of G. flavicoxis decreased markedly over time, so only the first days production need be used in mass rearing. The reduction in the proportion and numbers of females among progeny as females aged is consistent with sperm depletion. Approximately 30% of females in all age classes mated to newly emerged males (day 0) produced all male progeny, whereas only 10-15% of those mated to older males failed to produce any daughters. When crosses with only male progeny were excluded from the analysis, females mated to males 1 d old had higher sex ratios in progeny than those mated to males in other age classes. In addition, females mated the day that they emerged tended to have progeny with the highest sex ratios.

Survey of the native insect natural enemies of Hyphantria cunea (Drury) (Lepidoptera: Arctiidae) in China

The fall webworm, Hyphantria cunea (Drury) (Lepidoptera: Arctiidae), is an invasive and important pest in China. Investigations on insect natural enemies have been conducted from 1996 to 1999 in five provinces and one municipality of China in order to select effective species for biological control. Two carabid predators (Coleoptera) and 25 parasitoid species were found, among which 23 were parasitic wasps (Hymenoptera), including five hyperparasitic species and two tachinid flies (Diptera). The two carabids preyed on young larvae inside webs, two braconid wasps parasitized larvae, and 18 parasitoid species attacked the fall webworm during the pupal and/or 'larval-pupal' stages. Among these parasitoids, there were one genus and nine species that are new to science and four species new to China, which were described and published by the senior author Yang. The average parasitism rates of fall webworm pupae were 25.8% and 16.1% in the overwintering generation and the first generation (summer generation), respectively. These findings reveal that these natural enemies play an important role in the natural control of the pest. Chouioia cunea Yang (Hymenoptera: Eulophidae), a gregarious pupal endo-parasitoid, was recommended as a promising biological control agent against the fall webworm in China.

New Records of Copidosoma Sosares (Walker) (Hymenoptera: Encyrtidae), A Parasitoid of the Parsnip Webworm (Depressaria Pastinacella (Duponchel)) (lepidoptera: Elachistidae), in Western North America

Copidosoma sosares (Walker) (Hymenoptera: Encyrtidae) is a specialized polyembryonic parasitic wasp native to Europe. Here we report the distribution of C. sosares from western North America. We located C. sosares parasitizing Depressaria pastinacella (Duponchel) (Lepidoptera: Elachistidae) from several sites throughout Colorado, Idaho, Montana, New Mexico, Oregon, South Dakota, Utah, and Wyoming. Specimens collected from the Netherlands and several populations in the western US were indistinguishable morphologically. Reciprocal crosses between individuals from the Netherlands and from the western US strongly suggest that US populations of this wasp are C. sosares. In view of the absence of any recorded effort to introduce this species for biological control or any other purpose, it is likely that this species was accidentally introduced along with its host sometime in the recent past.

Fecundity and feeding of Galerucella calmariensis and G. pusilla on Lythrum salicaria

Fecundity and feeding of two introduced sibling biological control species, Galerucella calmariensis and G. pusilla (Coleoptera: Chrysomelidae) on purple loosestrife, Lythrum salicaria L. (Lythraceae) were compared at constant temperatures of 12.5, 15, 20, 25, and 27.5 °C. Larval feeding was also carried out at 30 °C, but at this temperature, larvae developed only to the L2 stage and none pupated. Thus, data for this temperature were not used in the analysis. There were significant species × temperature interactions in fecundity. Of the two species, Galerucella pusilla laid more eggs. Although egg production of both species was lowest at 12.5 °C and increased to 20 °C, at higher temperatures, the two species reacted differently. From 25 to 27.5 °C, egg production decreased for G. pusilla, but G. calmariensis fecundity peaked at 27.5 °C. Significant temperature × species × life-stage interactions were also observed in feeding. For each species, the amount of feeding varied with temperature and stage of development. Galerucella pusilla adults consumed more foliage at 15, 20, and 27.5 °C. However, at 12.5 °C G. calmariensis adults fed more than G. pusilla. G. pusilla larvae consumed an average of 25% less foliage than G. calmariensis. The lower larval consumption of G. pusilla suggests that when food is limited, G. pusilla larvae may have a higher survival rate because of its ability to complete larval development with less food and produce more progeny due to its greater fecundity. When food is not limited neither species would have a competitive advantage and both species could coexist temporally and spatially. However, since G. calmariensis larvae consumed more leaf material, the larval stage of this species would have a greater impact on purple loosestrife than G. pusilla.

Egg parasitoids of the genus Trichogramma (Hymenoptera, Trichogrammatidae) in olive groves of the Mediterranean region

A survey of egg parasitoids of the genus Trichogramma (Hymenoptera, Trichogrammatidae) was carried out in olive groves in Portugal, Greece, Egypt, and Tunisia during the years 2002–2004. Parasitoids were obtained either by exposing sentinel eggs (Sitotroga cerealella Olivier or Ephestia kuehniella Zeller) on olive trees or by collecting eggs of lepidopterous olive pests. Parasitized egg samples were reared separately in the laboratory for emergence of parasitoids. These were further reared in separate lines and processed by morphological and molecular biology techniques for species characterization. The recorded fauna of Trichogramma parasitoids in olive groves was species poor and consisted of species mainly known from the Mediterranean region. Trichogramma bourarachae Pintureau and Babault was found in Tunisia and Egypt, T. cordubensis Vargas and Cabello, and T. euproctidis Girault in Egypt, Trichogramma cacoeciae Marchal in Portugal, Greece, Egypt, Tunisia and Trichogramma nerudai Pintureau and Gerding in Portugal. Apart from that, Trichogramma oleae Voegelé and Pointel was collected in Tunisia. This species is probably not indigenous, but has established after several releases of a French strain were made in recent years. For selected strains, the sequence of the internal transcribed spacer 2 (ITS-2) region of rDNA was determined and deposited in the GenBank database. Differences in important biological attributes were found among collected strains of T. bourarachae, suggesting the existence of biotypes. The results contribute to the limited knowledge on distribution and biodiversity of the genus Trichogramma in the Mediterranean region. They can be helpful for the preservation and use of indigenous Trichogramma species in biological control of lepidopterous pests in olive and other local crops.

Gluconic acid: An antifungal agent produced by Pseudomonas species in biological control of take-all

Pseudomonas strain AN5 ( Ps. str. AN5), a non-fluorescent Australian bacterial isolate, is an effective biological control (biocontrol) agent of the take-all disease of wheat caused by the fungus Gaeumannomyces graminis var. tritici ( Ggt). Ps. str. AN5 controls Ggt by producing an antifungal compound which was purified by thin layer and column chromatography, and identified by NMR and mass spectroscopic analysis to be d-gluconic acid. Commercially bought pure gluconic acid strongly inhibited Ggt. Two different transposon mutants of Ps. str. AN5 which had lost take-all biocontrol did not produce d-gluconic acid. Gluconic acid production was restored, along with take-all biocontrol, when one of these transposon mutants was complemented with the corresponding open reading frame from wild-type genomic DNA. Gluconic acid was detected in the rhizosphere of wheat roots treated with the wild-type Ps. str. AN5, but not in untreated wheat or wheat treated with a transposon mutant strain which had lost biocontrol. The antifungal compounds phenazine-1-carboxylic acid and 2,4-diacetylphloroglucinol, produced by other Pseudomonads and previously shown to be effective in suppressing the take-all disease, were not detected in Ps. str. AN5 extracts. These results suggest that d-gluconic acid is the most significant antifungal agent produced by Ps. str. AN5 in biocontrol of take-all on wheat roots.

The potential of five Western Australian native Acacia species for biological control of Phytophthora cinnamomi

Five Acacia species native to Western Australia were assessed for their potential to protect the highly susceptible species Banksia grandis Wield from infection by the plant pathogen Phytophthora cinnamomi Rands. In a rehabilitated bauxite pit at Jarrahdale 55 km south-east of Perth and in a glasshouse trial, B. grandis planted either alone or with A. pulchella R.Br., A. urophylla Benth., A. extensa Lindl., A. lateriticola Maslin or A. drummondii Lindl., was soil inoculated with P. cinnamomi. It could only be shown that A. pulchella significantly protected B. grandis from P. cinnamomi infection in the rehabilitated bauxite pit trial up to 1 year after inoculation. This confirms the potential of this species for biological control of the pathogen in infested plant communities. The observed protection was not the result of a decrease in soil temperature or moisture. Protection was not emulated in a glasshouse trial where optimum environmental conditions favoured P. cinnamomi. Despite a delay in infection of B. grandis planted with Acacia spp., none of the five species definitively protected B. grandis from P. cinnamomi. However, in the glasshouse trial, A. pulchella, A. extensa, A. lateriticola and A. drummondii did significantly reduce the soil inoculum of P. cinnamomi, indicating a possible biological control effect on the pathogen. The mechanisms of biological control are discussed and the implications for management of rehabilitated bauxite mined areas and forests severely affected by P. cinnamomi are considered.

Lessons From History: Predicting Successes and Risks of Intentional Introductions for Arthropod Biological Control

The introduction of nonnative biological control agents into a new region is one of the several approaches to managing the deleterious effects of nonnative invasive species. Predicting outcomes of such introductions has proven difficult. The US National Invasive Species Management Plan (2001) calls for better screening methods for intentional introductions, including nonnative biological control agents for animal pests. To address this challenge, I searched current and historical literature to develop a database of 13 life history traits and 8 descriptive variables for 87 nonnative insect biological control species in the continental United States. Models for predicting success in controlling a target species and likelihood of nontarget effects (documented cases of attacks on native hosts, prey, or natural enemies) were developed using logistic regression. The most important life history traits for predicting success included host specificity, whether the agent was a predator or parasitoid, and number of generations per year. There was no information about nontarget effects in 50 of 87 cases. Traits important for predicting nontarget effects included sex ratio of progeny and the documented presence of native natural enemies. This quantitative approach, derived from a meta-analysis of historical data, can be useful in developing guidelines for intentional introductions and predicting ecological outcomes of a broader range of nonnative species in new environments.