Bagrada bug,
Bagrada hilaris
(Burmeister) (Hemiptera, Pentatomidae), has become a major pest of cole crops (cabbage, broccoli, cauliflower, kale) in California since its arrival in 2008. In this ...study we documented parasitism of
B. hilaris
eggs at a highly infested site in northern California by deploying sentinel
B. hilaris
eggs and collecting naturally-laid
B. hilaris
eggs in the soil. Two parasitoids,
Gryon aetherium
Talamas (Hymenoptera, Scelionidae) and
Ooencyrtus californicus
Girault (Hymenoptera, Encyrtidae), emerged from sentinel eggs, but only
G. aetherium
was documented attacking eggs in the soil.
Gryon aetherium
is currently being assessed as a classical biological control agent for
B. hilaris
in California, and mating experiments showed that crosses between
G. aetherium
from Pakistan and California yielded viable female offspring. This report marks the first known record of
G. aetherium
in the USA, and further work should be conducted to assess the potential of this parasitoid for biological control of
B. hilaris
.
Manipulating the factors that influence progeny production and sex ratio in parasitoids can help maximize the production of quarantine bioassays and/or mass releases. In a series of experiments, we ...studied the effects of several factors on offspring production and sex ratio in the parasitoid Gryon aetherium (Hymenoptera: Scelionidae), a candidate biological control agent for Bagrada hilaris (Hemiptera: Pentatomidae). Progeny production was influenced by maternal age and dropped when females were 24 or 28 days old and decreased on the second day of exposure. Overall, the offspring sex ratio was highly variable in G. aetherium and was affected by the duration of exposure, with higher proportions of females emerging after one day of exposure than after two days, but was not affected by female density, female age/host deprivation, or temperature during oviposition. Progeny production was affected by the temperature during oviposition and was highest at 26.6 °C. The results indicate that production of G. aetherium can be maximized at one day of exposure, using females that are less than 24 d old, and at temperatures of around 26 °C.
Phthorimaea absoluta (Meyrick) (= Tuta absoluta) (Lepidoptera: Gelechiidae), is the most damaging insect pest threatening the production of tomato and other solanaceous vegetables in many countries. ...In this study, we predicted the risk of establishment and number of generations for P. absoluta in the current and future climatic conditions under two Shared Socioeconomic Pathways (SSP2-4.5 and SSP5-8.5) of the years 2050 and 2070 using insect life cycle modelling (ILCYM) software. We used a temperature-dependent phenology model to project three risk indices viz., establishment risk index (ERI), generation index (GI), and activity index (AI) based on temperature data. The model projected large suitable areas for P. absoluta establishment in the Southern hemisphere under current and future climatic scenarios, compared to the Northern part. However, the risk of P. absoluta is expected to increase in Europe, USA, Southern Africa, and some parts of Asia in the future. Under current conditions, P. absoluta can complete between 6 and 16 generations per year in suitable areas. However, an increase in GI between 1 and 3 per year is projected for most parts of the world in the future, with an increase in AI between 1 and 4. Our results provide information on the risk of establishment of P. absoluta which could guide decision-makers to develop control strategies adapted for specific agro-ecological zones.
Nectar and pollen are critical for the survival and reproductive success of many natural enemy species, but are often lacking in agricultural monocultures. To enhance the effectiveness of natural ...enemies in agroecosystems, candidate insectary plants must be screened for traits that are appropriate for the targeted natural enemies. In this study, we screened three commonly-used insectary plants and six potentially harvestable flowering plants for their attractiveness to predatory hoverflies and other beneficial insects and pests. The common insectary plant sweet alyssum flowered the longest and consistently attracted the most predatory hoverflies and the least honey bees.
Display omitted
► The common insectary plant sweet alyssum attracted the most hoverflies. ► Potentially harvestable plants attracted mainly honey bees. ► Sweet alyssum stayed in bloom the longest of all tested plants. ► Sweet alyssum also contained the highest numbers of predatory hemipterans.
Resources for natural enemies are often lacking in agricultural fields. The provisioning of floral resources in crop fields can ameliorate this problem by providing nectar and pollen to natural enemies. To select an appropriate floral resource, plants must be screened for their flowering times and attractiveness to natural enemies and pests. We tested the attractiveness of nine species of annual flowering plants to hoverflies, which are important predators of aphids in California lettuce fields. We also sampled arthropods in the foliage of tested plants, to assess the abundances of other natural enemy and pest species that were present. Tested plants included three commonly-used insectary plants and six flowering plant species that showed potential as either harvestable herbs or cut flowers. Harvestable insectary plants may provide additional economic incentive for growers to set aside land for floral resources. The commonly-used insectary plant sweet alyssum consistently attracted the most hoverflies and the least bees, while potentially harvestable plants attracted few hoverflies. Competition with bees may have reduced hoverfly visits to several of the tested plant species. Sweet alyssum also stayed in bloom the longest, and contained the highest numbers of predatory hemipterans. Results suggest that plants should be screened for their attractiveness to not only the target biological control agent, but also to other potential competitors for floral resources. While this initial study focused on a limited selection of harvestable annual plants, a wide variety of other marketable plant species, particularly perennials, remain to be tested for their attractiveness to hoverflies or other beneficial arthropods.
The vine mealybug (VMB), Planococcus ficus (Hemiptera: Pseudococcidae), is a key insect pest of vineyards, and improvements in sustainable control of this pest are needed to meet increasing consumer ...demand for organically farmed products. One promising option is mating disruption. In a series of experiments conducted from 2004 to 2007, we tested the effects of mating disruption on trap captures of Pl. ficus males in pheromone-baited traps, on Pl. ficus numbers and age structure on vines, and on damage to grape clusters. From 2004 to 2005, the effects of dispenser load (mg active ingredient per dispenser) were also assessed, and dispensers were compared to a flowable formulation. Across all trials, mating disruption consistently reduced pheromone trap captures and often reduced mealybug numbers on vines and/or crop damage, regardless of the pheromone dose that was applied. Reductions in Pl. ficus densities in mating disruption plots were not accompanied by clear effects on mealybug population age structure; however, production of non-viable ovisacs by unmated females may have obscured differences in proportional representation of ovisacs. Pheromone trap captures were never lowered to zero (often called trap shut down), possibly because trials were conducted in vineyards with unusually high Pl. ficus densities. Trap-capture patterns in both treated and control plots commonly began low in April–May, increased in mid-July or August, and often decreased in September–October when post-harvest insecticides were applied. During the four-year trial, the release rate from plastic sachet dispensers was improved by industry cooperators as pheromone was released too quickly (2004) or not completely released during the season (2005–2006). The flowable formulation performed slightly better than dispensers at the same application dose. Results over all years suggest season-long coverage or late-season coverage may be as or more important than dose per hectare. Development of a dispenser with optimized season-long pheromone emission or targeted seasonal periods should be a future goal.
The reduction in floral diversity that often accompanies agricultural intensification may compromise the effectiveness of many natural enemies. Field studies examining the effects of floral resources ...on natural enemy fitness have been rare, however, particularly for predators such as hoverflies. Making the link between the presence of floral resources and the suppression of herbivores in crop fields has proved difficult. We investigated the effects of the floral resource plant sweet alyssum, Lobularia maritima (L.) Desv. (Brassicaceae), on aphid suppression by the hoverfly Eupeodes fumipennis (Thomson) (Diptera: Syrphidae) in California lettuce fields. The presence of alyssum in field cages significantly enhanced hoverfly egg production, resulting in more hoverfly larvae and fewer aphids (Hemiptera: Aphididae). Hoverfly survival was unaffected by alyssum, indicating that the indirect effect of alyssum on aphids was mediated primarily through the reproductive component of hoverfly fitness. Alyssum and other plant species are used to enhance resources for natural enemies in agricultural landscapes, and the results of this study provide some of the clearest evidence to date that increasing floral resource availability can enhance pest suppression and crop quality through elevated natural enemy fitness.
Two egg parasitoids from Pakistan, Gryon sp. nr. gonikopalense Sharma (Hymenoptera: Scelionidae) and Trissolcus hyalinipennis Rajmohana & Narendran (Hymenoptera: Scelionidae), are currently being ...investigated as potential classical biocontrol agents for Bagrada hilaris Burmeister. The former is the most promising because of its ability to attack B. hilaris eggs in soil, but the latter was recently discovered in California. This study detailed the patch use and oviposition behavior of both species and assessed their relative foraging efficiency. We also investigated possible competitive interactions by assessing 1) the occurrence of intra- and interspecific host discrimination, 2) mutual interference between females (extrinsic competition), 3) the outcome of multiparasitism (intrinsic competition), and 4) the effect of competition on host suppression. Our results showed that T. hyalinipennis females tended to probe repeatedly in the same hosts leading to longer host patch time and lower foraging efficiency. Both species avoided conspecific superparasitism, but not multiparasitism. When the two species foraged simultaneously, G. sp. nr. gonikopalense seemed to be slightly superior in extrinsic competition, while neither species seemed to have an advantage in intrinsic competition. Also, neither species could develop as a facultative hyperparasitoid, but they inflicted non-reproductive mortality on eggs containing 4-d-old larvae of their competitor. Lastly, host mortality inflicted by G. sp. nr. gonikopalense and T. hyalinipennis when acting together appeared to be additive. These results suggest that the presence of T. hyalinipennis in California is unlikely to reduce G. sp. nr. gonikopalense efficiency, but will instead improve the biological control of B. hilaris.
The presence of intact natural ecosystems in agricultural landscapes can mitigate losses in the diversity of natural enemies and enhance ecosystem services. However, native natural enemies may fail ...to persist in agroecosystems if invaders dominate species interactions. In this study, native and nonnative spiders were sampled along transects that extended from oak woodland and riparian zones into surrounding California vineyards, to assess the role of natural habitat as a source for spider biodiversity in the vineyard landscape, and to compare the dominance of exotic Cheiracanthium spiders between habitats. Many spider species were more abundant in natural habitat than in vineyards, and numbers of spiders and spider species within vineyards were higher at the vineyard edge adjacent to oak woodland. These results suggest that natural habitat is a key source for spiders in vineyards. The positive effect of oak woodland on the vineyard spider community extended only to the vineyard edge, however. Proportions of Cheiracanthium spiders increased dramatically in the vineyard, while numbers of native wandering spiders (the native ecological homologues of Cheiracanthium spiders) decreased. Dispersal limitation and strong habitat preferences may have prevented native wandering spiders from establishing far from the vineyard edge. Exotic Cheiracanthium spiders, in contrast, may possess specific adaptations to vineyards or to a wide range of habitats. Results suggest that the ecosystem services provided by intact natural habitat may be limited in agricultural landscapes that are dominated by invasive species.
SUMMARY
Background
It is well established that as a blood unit ages, fewer of the unit's red blood cells (RBCs) remain in circulation post‐transfusion. The mechanism for clearance is not well ...defined. Phosphatidylethanolamine (PE) is a phospholipid that is primarily found on the inner leaflet of healthy cells, and is an important ligand for phagocytosis of dead cells when exposed.
Objectives
The objective of the present study was to measure the change in PE exposure in donor RBCs over increasing storage ages using the novel PE‐specific probe, duramycin.
Methods
Five adsol (AS‐1) preserved RBC units were sampled weekly for 6 weeks and were labelled with duramycin. The percentage of PE exposed on red cells in each sample was determined using flow cytometry. Surface phosphatidylserine (PS) was evaluated for comparison.
Results
We found that RBCs in AS‐preserved donor units increasingly exposed PE, from less than 1% in freshly processed RBCs, to nearly 20% at 42 days of storage and correlated with increased relative vesiculation or microparticle concentration and release of cell‐free haemoglobin. By comparison, only 5% of cells exposed PS at 42 days.
Conclusion
We conclude that exposure of PE in the RBC outer membrane was higher than that of PS during 42 days of storage and correlated significantly with increased vesiculation and release of haemoglobin.
PDF
