Pheromone Deployment Strategies for Mating Disruption of a Vineyard Mealybug.

The mealybug, Planococcus ficus (Signoret), is a primary vineyard pest in California and other grape-growing regions throughout the World. Mating disruption programs are commercially available to manage Pl. ficus, but widespread adoption has been limited, in part, by high costs compared with insecticide programs. To improve mating disruption economic effectiveness, different deployment technologies (passive, aerosol, and microencapsulated formulations) were individually examined. Adult male Pl. ficus captures in pheromone traps and categorical ratings of vine infestation or crop damage suggest that all deployment strategies lowered mealybug densities or damage. Using passive dispensers, deployment rates of 310 and 465 per ha lowered Pl. ficus crop damage similar to 615 per ha, a rate commonly used in commercial operations; reduced rates would lower product and deployment costs. Meso dispensers, containing more a.i., deployed at 35 per ha did not have a treatment impact, but a microencapsulated formulation and aerosol canisters lowered male flight captures and/or crop damage. Male mealybug flight activity was greatest from 0500-1100 hr, which coincided with temperatures >16° and <32°C. These restricted times and temperatures suggest programable dispensers might allow pheromone deployment to coincide only with flight patterns. A large field trial using passive dispensers found greater treatment separation after 3 yr of pheromone deployment. Discrepancies in results among vineyards may be related to Pl. ficus density, but combined results from all trials suggest that different deployment technologies can be used to impact Pl. ficus densities and damage, even at reduced rates, especially with continued use over multiple seasons.

You are what you eat: fatty acid profiles as a method to track the habitat movement of an insect.

Tracking the movement of small organisms is of tremendous importance to understanding the ecology of populations, communities, and ecosystems. However, it remains one of the most difficult challenges facing the field of movement ecology. We developed an intrinsic marking technique for tracking small organisms using dietary fatty acid profiles as a biomarker as well as for clarifying source-sink dynamics between populations on a landscape level. Navel orangeworm moths (NOW), Amyelois transitella (Walker) (Lepidoptera: Pyralidae), raised on two different host plants with significantly different fatty acid profiles, were used to develop a model that distinguishes NOW based on their larval host plant. Wild NOW from both known and unknown host plants were used to validate the model. NOW fatty acid profiles showed striking similarities to the fatty acid profile of their host plant demonstrating that fatty acids can act as an intrinsic marking technique for quantifying the movement of small organisms. We anticipate that given sufficient spatial variation in dietary fatty acids, this technique will be useful in studying the movement of arthropods and other invertebrates particularly when addressing questions of source-sink dynamics.

Genetic divergence is decoupled from ecological diversification in the Hawaiian Nesosydne planthoppers.

Adaptive radiation involves ecological shifts coupled with isolation of gene pools. However, we know little about what drives the initial stages of divergence. We study a system in which ecological diversification is found within a chronologically well-defined geological matrix to provide insight into this enigmatic phase of radiation. We tested the hypothesis that a period of geographic isolation precedes ecological specialization in an adaptive radiation of host-specialized Hawaiian planthoppers. We examined population structure and history using mitochondrial and multiple independent microsatellite loci in a species whose geographic distribution on the island of Hawaii enabled us to observe the chronology of divergence in its very earliest stages. We found that genetic divergence is associated with geographic features but not different plant hosts and that divergence times are very recent and on the same timescales as the dynamic geology of the island. Our results suggest an important role for geography in the dynamics of the early stages of divergence.

Emergence asynchrony between herbivores leads to apparent competition in the field.

It has been established that herbivore populations can be structured by apparent competition, even if they do not compete directly for resources. But we lack evidence on the mechanisms behind such indirect competition. This study shows that temporal asynchronies in emergence time lead to apparent competition via shared natural enemies in a leafminer-parasitoid community. We present three kinds of evidence on mechanisms driving apparent competition. First, we conducted a two-year population census of Liriomyza helianthi and Calycomyza platyptera, along with all associated parasitoids, at seven sites in the Californian Central Valley, USA. We then assessed C. platyptera parasitism on 16 vegetation islands, half with experimental removal of early-season L. helianthi populations. Finally, we examined parasitoid host preference between leafminer species. We found that Liriomyza helianthi populations emerged approximately one month before C. platyptera. Experimental removal of L. helianthi populations in the early summer led to a 60% reduction in parasitism of C. platyptera. We found no evidence of differential parasitoid preference for host species. The findings suggest that temporal asynchrony can lead to negative effects on later-emerging species and that such indirect competition may be a major structuring force in herbivore communities.

History of IPM in California pears--50 years of pesticide use and the transition to biologically intensive IPM.

During the 1960s, the California pear industry, on a per acre basis, was among the heaviest users of pesticides. Each season, multiple sprays of up to 14 active ingredients (chlorinated hydrocarbons, organophosphates and carbamates) were typically applied for control of insects and mites. The cost of control escalated while damage from arthropod pests increased owing to greater pest resistance and more pest resurgence. The pear industry suffered classic symptoms of the 'pesticide treadmill'. By the late 1960s, key pear industry leaders demanded action. Simultaneously, newly emerging concepts of IPM were being developed and funded. With public awareness and environmental activism on the rise in the wake of Rachel Carson's Silent Spring, the stage was set for change. This paper elucidates how pear growers, university researchers and extension agents, environmentalists, government regulators, private consultants, farm chemical suppliers and others contributed to the reduction in insecticide use in California pear orchards. Today, arthropod IPM in pears is characterized as relatively low input, biologically intensive and very successful. For example, in 2008 many pear growers only applied between three and five active ingredients (mainly organically certified) per season for control of arthropods.

Isolation and characterization of microsatellite markers in an endemic Hawaiian planthopper (Nesosydne chambersi: Delphacidae).

We have isolated and characterized 17 microsatellite loci for the endemic Hawaiian planthopper Nesosydne chambersi (Delphacidae), a member of a large Hawaiian Nesosydne radiation. Thirty individuals from one population and 10 individuals from two populations across the species' range were tested to investigate polymorphism. The observed loci contained two to nine alleles per locus. Expected heterozygosity within this species ranged from 0.2 to 0.85. These markers will be used to assess intraspecific differentiation and population structure within N. chambersi.

Contrasting the Tolerance of Wild and Domesticated Tomatoes to Herbivory: Agroecological Implications.

Application of plant life-history theory to strategies for breeding crop plants for sustainable agriculture remains relatively unexplored. We determined the relative tolerance of wild and domesticated tomatoes to simulated herbivory and evaluated plant characteristics that may contribute to tolerance. Wild and domesticated tomatoes were subjected to different levels of defoliation ranging from 0 to 70%. Single defoliation events at lower levels (15-30%) did not significantly affect total fruit mass produced in either wild or domesticated tomatoes. Increased defoliation resulted in significant reductions in total fruit mass per plant and mean mass per fruit. Reduction in fruit output by the cultivar was °3 times greater than the wild tomato for the first 8 wk of fruit production, whereas the loss in seasonal fruit production by the cultivar was 1.7 times greater than the wild tomato. We concluded that domestication of tomatoes may have decreased their relative tolerance to herbivory. Possible mechanisms for decreased tolerance include differences in leaf area index, light capture curves, and the relative allocation pattern to vegetative growth vs. reproductive structures. Optimization of potential life-history trade-offs between tolerance to herbivory and maximum fruiting abilities are proposed for cultivars of sustainable agriculture.