House fly attraction to field-collected plant materials contaminated with honeydew.

<p>Fifty female flies were used per replicate, with a maximum of 8 replicates per 24 hr assay period. Data were analyzed by paired t-test for comparisons within each row. “% Response to treatment” is the total number of house flies captured on the treatment over the total flies captured on both treatment and control.</p><p>*One or more replicates were discarded due to a cage failure allowing flies to access the test material within a beaker.</p><p>House fly attraction to field-collected plant materials contaminated with honeydew.</p

House fly attraction to plant materials infested with honeydew-producing insects.

<p>Fifty female flies were used per replicate, with 8 replicates per 24 hr bioassay period. Data were analyzed with ANOVA for the first comparison and by paired t-test for the remaining comparisons within each row. “% Response to treatment” is the total number of house flies captured on the treatment over the total flies captured on both treatment and control.</p><p>*Indicates that 1 or more replicates were discarded due to a cage failure allowing flies to access the test material within a beaker.</p><p>House fly attraction to plant materials infested with honeydew-producing insects.</p

House Fly (<i>Musca domestica</i> L.) Attraction to Insect Honeydew

<div><p>House flies are of major concern as vectors of food-borne pathogens to food crops. House flies are common pests on cattle feedlots and dairies, where they develop in and feed on animal waste. By contacting animal waste, house flies can acquire human pathogenic bacteria such as <i>Escherichia coli</i> and <i>Salmonella</i> spp., in addition to other bacteria, viruses, or parasites that may infect humans and animals. The subsequent dispersal of house flies from animal facilities to nearby agricultural fields containing food crops may lead to pre-harvest food contamination with these pathogens. We hypothesized that odors from honeydew, the sugary excreta produced by sucking insects feeding on crops, or molds and fungi growing on honeydew, may attract house flies, thereby increasing the risk of food crop contamination. House fly attraction to honeydew-contaminated plant material was evaluated using a laboratory bioassay. House flies were attracted to the following plant-pest-honeydew combinations: citrus mealybug on squash fruit, pea aphid on faba bean plants, whitefly on navel orange and grapefruit leaves, and combined citrus mealybug and cottony cushion scale on mandarin orange leaves. House flies were not attracted to field-collected samples of lerp psyllids on eucalyptus plants or aphids on crepe myrtle leaves. Fungi associated with field-collected honeydews were isolated and identified for further study as possible emitters of volatiles attractive to house flies. Two fungal species, <i>Aureobasidium pullulans</i> and <i>Cladosporium cladosporioides</i>, were repeatedly isolated from field-collected honeydew samples. Both fungal species were grown in potato dextrose enrichment broth and house fly attraction to volatiles from these fungal cultures was evaluated. House flies were attracted to odors from <i>A</i>. <i>pullulans</i> cultures but not to those of <i>C</i>. <i>cladosporioides</i>. Identification of specific honeydew odors that are attractive to house flies could be valuable for the development of improved house fly baits for management of this pest species.</p></div

Fungi collected from honeydew-contaminated plant material.

<p>Numbers are presented as colony forming units/100 μl or CFU/100ul. Rows above the double line are the honeydew-contaminated plant materials that were attractive to house flies. Rows below the double line were materials that were not attractive to flies. “Tmt” is treatment leaves or fruit containing insects and honeydew. “Ct” is control leaves or fruit with no visible insects or honeydew.</p><p>* Indicates there was overgrowth of the <i>Aureobasidium</i> and <i>Cladosporium</i> so that other specimens could not be identified.</p><p>Fungi collected from honeydew-contaminated plant material.</p

House fly attraction to odors from fungi isolated from honeydew and cultured on potato dextrose broth (PDB).

<p>Fifty female flies were used per replicate, with 8 replicates tested per 24 hr-assay period. Data were analyzed by paired t-test for comparisons in each row. “% Response to treatment” is the total number of house flies captured on the treatment over the total flies captured on both treatment and control.</p><p>House fly attraction to odors from fungi isolated from honeydew and cultured on potato dextrose broth (PDB).</p

A diagram of a cage bioassay set up.

<p>Beakers containing either honeydew and plant material or a control were placed about 10 cm apart in a 45 × 45 × 45 cm cage. Sticky traps (sticky surface down) placed above each beaker captured flies near the beaker’s opening.</p

Fungal densities of <i>Aspergillus</i> spp. in almond and pistachio orchards at the Kearney Agricultural Research and Extension Center in Parlier, CA.

<p>In both crops, <i>Aspergillus</i> spp. fungi increase after the second week of August. Developing almond fruits were not examined in September 8^th.</p

Shannon-Weiner diversity indices of fungal species detected in four almond cultivars during the course of the study in an experimental orchard at the Kearney Agricultural Research and Extension Center in Parlier, CA.

<p>Shannon-Weiner diversity indices of fungal species detected in four almond cultivars during the course of the study in an experimental orchard at the Kearney Agricultural Research and Extension Center in Parlier, CA.</p