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Stem and wood boring beetles significantly damage kharsu oak trees leading to their mortality and decline in the Garhwal region of Western Himalaya, India. The relationship established between the prevalent biotic factors (extensive lopping and grazing) and the degree of borer infestation in Chakrata hills, Uttarakhand, revealed a strong correlation between the two. Density-girth class relationship in borer-infested oak stands revealed a higher degree of past disturbance compared to uninfested oak stands, with maximum infestation in girth class 61-80 cm and between 2601 and 2700 msl. [ABSTRACT FROM AUTHOR]

The broom leaf beetle (Gonioctena olivacea) and the Honshu white admiral butterfly (Limenitis glorifica) have been introduced into New Zealand as biocontrol agents of the weeds Scotch broom (Cytisus scoparius) and Japanese honeysuckle (Lonicera japonica) respectively. However, neither agent has been successful yet. Larval predation of these species could be a factor affecting their success, and this hypothesis was tested using various predator-exclusion treatments. Survival of broom leaf beetle larvae increased c. five-fold by sleeving Scotch broom seedlings in fine mesh. In contrast, survival was unaffected by excluding either crawling predators using sticky barriers or larger predators using chicken wire. Survival of Honshu white admiral butterfly larvae increased c. ten-fold by excluding either crawling predators using sticky barriers or flying predators using a fine-mesh sleeve. Simultaneously excluding both crawling and flying predators resulted in a c. 23-fold increase in survival. These results suggest that larval predation could be limiting the populations of both broom leaf beetle and Honshu white admiral. Future biocontrol programmes could prioritise candidate agents accordingly. [ABSTRACT FROM AUTHOR]

The ant Oecophylla longinoda Latreille forms a trophobiotic relationship with the invasive mealybug Rastrococus iceryoides Green and promotes the latter's infestations to unacceptable levels in the presence of their natural enemies. In this regard, the antagonistic interactions between the ant and the parasitoid Anagyrus pseudococci Girault were assessed under laboratory conditions. The percentage of parasitism of R. iceryoides by A. pseudococci was significantly higher on "ant-excluded" treatments (86.6% ± 1.27%) compared to "ant-tended" treatments (51.4% ± 4.13%). The low female-biased sex-ratio observed in the "ant-tended" treatment can be attributed to ants' interference during the oviposition phase, which disrupted parasitoids' ability to fertilize eggs. The mean foraging time, host handling time and number of successful oviposition in "ant-excluded" treatment were significantly higher compared to "ant-tended" treatments. When ant workers were allowed access to sterilized sand grains, mummified and unmummified R. iceryoides, they selectively removed the mummified mealybugs, indicating that they recognized the mummies as potential foods (1.2 ± 0.46 to 7.8 ± 1.17 mummies at 10 min intervals for 2 h). Percentage emergence from mummified R. iceryoides removed by the ants was significantly lower compared to emergence from mummies not exposed to ants. Although, host seeking parasitoids frequently evaded attacks, some were killed by the foraging ant workers (2.0 ± 0.38 to 6.0 ± 0.88 at 10 min intervals for 2 h). These results suggest for the first time that the presence of O. longinoda has a detrimental effect on the abundance, reproductive success and possibly oviposition strategy of female parasitoids, which might be a delimiting factor in field conditions if both natural enemies are to be recommended for use within the same agro-ecosystem. [ABSTRACT FROM AUTHOR]

The fruit fly, Bactrocera invadens is an alien invasive pest of mango in Africa. The predatory African weaver ant, Oecophylla longinoda is being promoted for managing B. invadens and classical biological control with the Opiine parasitoid, Fopius arisanus is also underway. The current study investigated interactions between these two natural enemies. Specifically we assessed whether semiochemicals deposited by the ant on leaves and fruit affected the landing behavior of F. arisanus , its patch residence time and subsequent parasitism rates. Results showed that significantly more F. arisanus landed on ‘ant-unexposed’ leaves and fruits (leaves: 3.8 ± 0.5–7.7 ± 0.8; fruits: 4.1 ± 0.1–8.1 ± 1.2) compared with ‘ant-exposed’ leaves and fruits (leaves: 0.4 ± 0.1–2.5 ± 0.3; fruits: 0.2 ± 0.1–2.8 ± 0.7) from mango, citrus, guava and avocado. Parasitoid patch residence times were significantly longer on ‘ant-unexposed’ mango fruits (654.2 ± 28.4 s–1034.2 ± 112.6 s) compared to ‘ant-exposed’ fruits (75.2 ± 18.4 s–144.8 ± 42 s) regardless of whether eggs of B. invadens were present. In terms of percent parasitism, F. arisanus achieved significantly higher parasitism rates in B. invadens from ‘ant-unexposed’ mango fruits (72.8 ± 3.8) compared with ‘ant-exposed’ fruits (18.2 ± 1.8). Regression analysis showed a significant inverse relationship between the duration of exposure of mango fruits to ant-produced semiochemicals and the number of F. arisanus adults landing on fruits and percent parasitism. In field cages, 32% parasitism of B. invadens was achieved in mango fruits on trees without ants and 11% in mango fruits on ant-infested trees. These results suggest the potential for biotic interference between the two natural enemies if they are recommended for use within the same ecosystem. [ABSTRACT FROM AUTHOR]

The ant Oecophylla longinoda Latreille forms a trophobiotic relationship with the invasive mealybug Rastrococus iceryoides Green and promotes the latter’s infestations to unacceptable levels in the presence of their natural enemies. In this regard, the antagonistic interactions between the ant and the parasitoid Anagyrus pseudococci Girault were assessed under laboratory conditions. The percentage of parasitism of R. iceryoides by A. pseudococci was significantly higher on “ant-excluded” treatments (86.6% ± 1.27%) compared to “ant-tended” treatments (51.4% ± 4.13%). The low female-biased sex-ratio observed in the “ant-tended” treatment can be attributed to ants’ interference during the oviposition phase, which disrupted parasitoids’ ability to fertilize eggs. The mean foraging time, host handling time and number of successful oviposition in “ant-excluded” treatment were significantly higher compared to “ant-tended” treatments. When ant workers were allowed access to sterilized sand grains, mummified and unmummified R. iceryoides, they selectively removed the mummified mealybugs, indicating that they recognized the mummies as potential foods (1.2 ± 0.46 to 7.8 ± 1.17 mummies at 10 min intervals for 2 h). Percentage emergence from mummified R. iceryoides removed by the ants was significantly lower compared to emergence from mummies not exposed to ants. Although, host seeking parasitoids frequently evaded attacks, some were killed by the foraging ant workers (2.0 ± 0.38 to 6.0 ± 0.88 at 10 min intervals for 2 h). These results suggest for the first time that the presence of O. longinoda has a detrimental effect on the abundance, reproductive success and possibly oviposition strategy of female parasitoids, which might be a delimiting factor in field conditions if both natural enemies are to be recommended for use within the same agro-ecosystem.

The florivorous weevilAnthonomus santacruziis being released in South Africa to reduce the reproductive capacity of the invasive tree,Solanum mauritianum. Initiated to allay concerns about biotic interference, our study suggests that inflorescence-inhabiting spiders pose no risk to the survival and proliferation ofA. santacruzipopulations in the field. [ABSTRACT FROM PUBLISHER]

Soil, water and species diversity relationships are central components of the vegetation ecology. In this connection, the present study was performed on the three sites within the campus of Banaras Hindu University of India, to relate herbaceous species diversity to soil physical characteristic and the intensity of biotic interferences. At each site, three, 10 m × 10 m plots were randomly established and within each plot, four quadrats each 50 cm × 50 cm were randomly placed for sampling. For each quadrat, number of individuals and their herbage cover were recorded by species. Soil physical characteristics (soil moisture, water-holding capacity, soil porosity and bulk density), elements of biotic interferences and α-diversity and its components were determined for each plot. The plots were ordinated by Non-metric Multidimensional Scaling (NMS) using Importance Value Indices of the component species. Results showed that the selected locations differed in terms of soil moisture and species diversity parameters due to differences in biotic interferences. NMS ordination yielded three groups corresponding to the three communities experiencing different intensity of land use. NMS axes were substantially related to the soil and herbaceous diversity parameters and suggested that the elements of soil physical characteristics, intensity of biotic interferences and regional herbaceous species pool had profound effect on the organization and determination of herbaceous floristic composition. Further, the sample locations exhibiting greater soil moisture, water-holding capacity, soil porosity and lesser soil bulk density harboured greater herbaceous diversity. A negative relationship between indices of species diversity and soil bulk density revealed that the dry and compact soils due to greater biotic pressure contributed to the loss of species diversity. Reduction in livestock numbers, grazing pressure and soil bulk density could be helpful in the promotion of soil quality and species diversity. [ABSTRACT FROM AUTHOR]

Abstract: The degree to which resident biota can inhibit the ability of an introduced biological control agent to establish and be effective is termed biotic interference. Studying biotic interference prior to a release using the actual agent is logistically difficult, however, due to quarantine restrictions. An alternative solution is to study biotic interference against a surrogate species in the intended range of introduction, with the expectation that biotic interference against the actual agent will be similar. This study assessed how biotic interference, mostly by generalist predators, may affect establishment of classical biological control agents of the soybean aphid, Aphis glycines Matsumura, in North America. The parasitoid Aphidius colemani Viereck was used as a surrogate for Asian aphidiine braconids such as Binodoxys communis (Gahan). We conducted a factorial field experiment that measured the effect of releasing A. colemani and of excluding resident natural enemies using field cages on soybean aphid populations. We also conducted molecular gut-contents analyses on predators collected in release plots to determine which species fed upon A. colemani. Releasing A. colemani in open field plots increased soybean aphid control beyond that observed in open field plots alone, despite indications that intraguild predation of A. colemani occurred. Thus, biotic interference was not sufficient to eliminate the contribution of A. colemani on soybean aphid suppression during the course of our experiment. Molecular gut-contents analysis revealed that at least two predators, Harmonia axyridis (Pallas) and Chrysoperla carnea Stephens, engaged in intraguild predation against A. colemani. The prolonged effect of intraguild predation on parasitoid establishment remains to be determined. [Copyright &y& Elsevier]

Miconia calvescens DC. (Melastomataceae) is an invasive tree considered one of the greatest threats to natural ecosystems of Hawaii and other Pacific islands. The potential for using the defoliator Antiblemma leucocyma (Lepidoptera: Noctuidae) as a biological control agent of M. calvescens was evaluated in the native habitat of the insect in Brazil. Impact assessment in the field showed that 37.2% of leaves presented damage by A. leucocyma, and among damaged leaves, 1.5-51.9% of the leaf area (16.3% on average) was affected. Damage was found in young to fully expanded leaves (28-915 cm2 in area). Individual A. leucocyma developing as third through sixth instars in the laboratory consumed an average of 1348 cm2 of M. calvescens leaf material in about 11 days. Populations of A. leucocyma in the field were heavily impacted (up to 83% parasitism) by a braconid parasitoid. Observations in the field and single- and two-host choice tests in the laboratory indicated that A. leucocyma has a narrow host range restricted to M. calvescens. Usefulness of this herbivore for biological control in Hawaii appears low, however, because of its probable susceptibility to generalist parasitoids. [ABSTRACT FROM AUTHOR]

In Iowa, predators may be limiting Galerucella species to densities below levels needed for biological control of purple loosestrife (Lythrum salicaria). A 2-year assessment of predatory arthropods and quantification of predation in the field provided an understanding of the trophic interactions that occur within L. salicaria-dominated Iowa wetlands. Whole-plant samples and presence/absence counts assessed canopy-dwelling arthropods, whereas pitfall traps were used to identify ground-dwelling spiders and insects weekly from May to August. Thirty-five families of spiders and 45 families of predatory insects were collected from L. salicaria-infested wetlands. Carabidae and Lycosidae were the most abundant ground-dwelling predators. Coccinellidae and Salticidae were the most abundant predators in the canopy. Both egg and larval field predation were assessed. Egg predation was evaluated by attaching sentinel egg masses to L. salicaria plants for 48 h. Average egg predation was 26% of egg masses. Paired open and closed cages containing 20 G. pusilla first instars on L. salicaria were placed in Iowa wetlands for 10 days (larval developmental time from first to third instars) to coincide with the natural occurrence of Galerucella larvae in the field. Larval predation was high, 46% for the first generation and 38% during the second generation. The observed levels of predation are likely a factor in decreasing the populations of Galerucella released for the biological control of L. salicaria. [Copyright &y& Elsevier]

The leaf beetle, Galerucella pusilla, is an introduced natural enemy of purple loosestrife, Lythrum salicaria, in North America. The suitability of G. pusilla eggs for development and survival of Chrysoperla carnea and Coleomegilla maculata was quantified by measuring preimaginal development, survival, and adult weight. Individual first-instar predators were assigned to one of two diets: G. pusilla eggs or a diet of Ephestia kuehniella eggs and pea aphids (Acyrthosiphon pisum) alternated every 24 h. Chrysoperla carnea and C. maculata larvae that fed on G. pusilla eggs had lower survival rates, longer developmental times, and reduced adult weight. Galerucella pusilla eggs were not suitable prey for 95% of C. maculata larvae, but 37% of C. carnea larvae completed development on G. pusilla eggs. Because G. pusilla eggs may be utilized by these predatory species as alternative prey during periods of low availability of suitable prey, this predation could affect the biological control of L. salicaria. [Copyright &y& Elsevier]

• Gorse thrips is an ineffective weed biocontrol agent in New Zealand. • A phytoseiid predator Amblyseius herbicolus occurs on gorse. • We studied thrips predation by A. herbicolus and two related mites. • High capture rates, low handling times infer effective thrips predation. • A. herbicolus predation may explain the failure of gorse thrips. Sericothrips staphylinus was introduced to New Zealand as a biological control agent for gorse, Ulex europaeus (Fabales: Fabaceae), an invasive weed of European origin, but has proven to be an ineffective agent. We investigated and compared the functional responses of a predatory mite found on gorse in New Zealand, Amblyseius herbicolus , with two well-known mite predators of thrips: Amblydromalus limonicus , and Neoseiulus cucumeris when fed on varying densities (2, 4, 8, 16, and 24/491 mm2) of S. staphylinus first instar larvae. We also compared the functional response of A. herbicolus on S. staphylinus with previously published data for mite predators of thrips. Amblyseius herbicolus , A. limonicus , and N. cucumeris all exhibited a type II functional response. A. herbicolus generally exhibited higher capture rates and lower handling times than those reported for other predatory mites that are effective biocontrol agents of pest thrips on crops, except for A. limonicus. These results indicate that the presence of A. herbicolus on gorse in New Zealand is a likely explanation for the failure of S. staphylinus as a weed biocontrol agent. [ABSTRACT FROM AUTHOR]

The ant Oecophylla longinoda Latreille forms a trophobiotic relationship with the invasive mealybug Rastrococus iceryoides Green and promotes the latter's infestations to unacceptable levels in the presence of their natural enemies. In this regard, the antagonistic interactions between the ant and the parasitoid Anagyrus pseudococci Girault were assessed under laboratory conditions. The percentage of parasitism of R. iceryoides by A. pseudococci was significantly higher on "ant-excluded" treatments (86.6% ± 1.27%) compared to "ant-tended" treatments (51.4% ± 4.13%). The low female-biased sex-ratio observed in the "ant-tended" treatment can be attributed to ants' interference during the oviposition phase, which disrupted parasitoids' ability to fertilize eggs. The mean foraging time, host handling time and number of successful oviposition in "ant-excluded" treatment were significantly higher compared to "ant-tended" treatments. When ant workers were allowed access to sterilized sand grains, mummified and unmummified R. iceryoides, they selectively removed the mummified mealybugs, indicating that they recognized the mummies as potential foods (1.2 ± 0.46 to 7.8 ± 1.17 mummies at 10 min intervals for 2 h). Percentage emergence from mummified R. iceryoides removed by the ants was significantly lower compared to emergence from mummies not exposed to ants. Although, host seeking parasitoids frequently evaded attacks, some were killed by the foraging ant workers (2.0 ± 0.38 to 6.0 ± 0.88 at 10 min intervals for 2 h). These results suggest for the first time that the presence of O. longinoda has a detrimental effect on the abundance, reproductive success and possibly oviposition strategy of female parasitoids, which might be a delimiting factor in field conditions if both natural enemies are to be recommended for use within the same agro-ecosystem.