Honeydew and insecticide bait as competing food resources for a fruit fly and common natural enemies in the olive agroecosystem

Abstract

Honeydew from phloem-feeding insects and fruit fly insecticidal baits may serve as adult food resources for some insect species. In California (USA) olive orchards, the black scale [Saissetia oleae (Olivier) (Hemiptera: Coccidae)] is a common honeydew producer, and spinosad-based fruit fly bait (GF-120) is used to control the olive fruit fly [Bactrocera oleae (Rossi) (Diptera: Tephritidae)]. We investigated the effects of black scale honeydew and GF-120, as food resources, on adult foraging behaviour and survival of the olive fruit fly and two parasitoids in the olive agroecosystem: Scutellista caerulea (Fonscolombe) (Hymenoptera: Pteromalidae), a natural enemy of black scale, and Psyttalia humilis (Silvestri) (Hymenoptera: Braconidae), a parasitoid of the fruit fly. In food choice tests, female flies did not show a preference between GF-120 bait and honeydew, whereas male flies and the parasitoids we tested preferred honeydew. Adults of the three insect species readily fed on honeydew, but the natural enemies never (P. humilis) or rarely (S. caerulea) fed on GF-120 bait. Olfactometer tests further confirmed that the tested natural enemies were not attracted to GF-120 bait. The presence of honeydew significantly reduced fruit fly mortality when both honeydew and GF-120 were provided, compared with GF-120 given alone. A single meal of honeydew increased longevity in all insect species tested. The mean longevities of honeydew-fed insects were not significantly different from those feeding on clover honey. Our results suggest that the presence of honeydew would benefit the three insect species and may reduce the efficacy of GF-120 for fruit fly control because of preference of honeydew rather than fruit fly bait as a food resource.

Overwintering Survival of Olive Fruit Fly (Diptera: Tephritidae) and Two Introduced Parasitoids in California

“…Food, water, and temperature are key factors inßuencing adult B. oleae survival (Wang et al 2009a,b;Yokoyama 2012). In olive orchards, natural food sources such as honeydew produced by Saissetia oleae (Olivier) may sustain the ßyÕs longevity (Wang et al 2011a). Even with a food supply, adult ßies are vulnerable to CaliforniaÕs low winter temperatures, as showed in this study, and high summer temperatures, as shown by Johnson et al (2011).…”

Are wild flowers and insect honeydews potential food resources for adults of the olive moth, Prays oleae?

“…The honeydew composition from S. oleae growing on Citrus sinensis L. contained fructose, sucrose and glucose, but no other carbohydrates (Byrne et al 2003). Wang et al (2011) found a positive effect of a single meal of S. oleae honeydew on the longevities of Bactrocera oleae (Rossi) (Diptera: Tephritidae) and the parasitoids Psyttalia humilis (Silvestri) (Hymenoptera: Braconidae) and Scutellista caerulea (Fonsc.) (Hymenoptera: Pteromalidae).…”

A Compound Produced by Fruigivorous Tephritidae (Diptera) Larvae Promotes Oviposition Behavior by the Biological Control AgentDiachasmimorpha longicaudata(Hymenoptera: Braconidae)

“…There are at least 5 potential sources of opiine-attractive compounds: fruit, other adult foods such as honey dew or flower-nectar (e.g., acetophenone from Lobularia maritima L. in Rohrig et al 2008;Sivinski et al 2006;Sivinski et al 2011;Wang et al 2011), fruit fly larvae (e.g., para-ethylacetophenone in Stuhl et al 2011b), the by-products of fruit fly infestation and decay (e.g., fungal-derived ethanol, acetaldehyde and acetic acid in Greany et al 1977; 2-phenylethyl acetate unique to infested mango [Mangifera indica L.] in Carrasco et al 2005), and adult-host semiochemicals (e.g., Prokopy & Webster 1978;Roitberg & Lalonde 1991). It seems possible that all of these, in one combination or another, might contribute to a useful monitoring system.…”