The fruit fly PUB: a phagostimulation unit bioassay system to quantitatively measure ingestion of baits by individual flies

Abstract

A bioassay to investigate quantitative phagostimulation and ingestion physiology of baits on individual fruit flies is presented. The study was undertaken using two fruit fly species: the Mediterranean fruit fly (Ceratitis capitata), a cosmopolitan insect pest, and the Ethiopian fruit fly (Dacus ciliatus), a quarantine insect in Israel. Our model bait suspension included spinosad as the toxic agent, and 1% yeast hydrolysate with 10% sucrose as phagostimulant. A preliminary toxicology study showed that the two fruit flies are highly sensitive to low concentrations of spinosad baited with this phagostimulant. The maximum concentration needed to kill 90% of the female flies was 4.2 and 8.5 p.p.m. for C. capitata and D. ciliatus, respectively. The bioassay was able to detect the ingestion of low volumes (e.g. 1 ll) of tested solutions. The bioassay was also able to detect differences in intake of different concentrations of spinosad solutions and relate ingestion to fruit fly mortality. Additionally, the bioassay was sensitive enough to highlight differences in intake related to the physiological status of the fruit fly and fly species. The bioassay can also be used to follow ingestion kinetics of baits. We expect that this bioassay will contribute in the exploration of more efficient bait systems for fruit flies.

Purification and characterisation of proteins secreted by the entomopathogenic fungus Metarhizium anisopliae with insecticidal activity against adults of the Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae)

“…The test suspension was offered to the flies at a concentration of 8 mg protein mL −1 , while controls were fed with the desalted Adamek's liquid protein fraction. In either assay, the ingested volumes in controls and treatments were calculated by measuring the suspension remaining in each microtube cap 26. Every day for a 5 day period before refilling the caps, the suspension remaining in each cap was removed with a 100 ± 5 µL disposal micropipette (Brand, Wertheim, Germany).…”

“…In either assay, the ingested volumes in controls and treatments were calculated by measuring the suspension remaining in each microtube cap. 26 Every day for a 5 day period before refilling the caps, the suspension remaining in each cap was removed with a 100 ± 5 µL disposal micropipette (Brand, Wertheim, Germany). Three units without flies were run in parallel to monitor evaporation.…”

Residual Control and Lethal Concentrations of GF-120 (spinosad) for Anastrepha spp. (Diptera: Tephritidae)

“…According to Edwards et al (2003) the increased consumption of the diluted product may result from the diluted product being easier to swallow. Nestel et al (2004) found that intake was signiÞcantly higher for low spinosad concentrations for both Dacus ciliatus Loew and C. capitata. This result was also observed when comparing a drop of fresh product with a drop of product after 24 h of application .…”

Bioassay Method for Toxicity Studies of Toxic Bait Formulations to Ceratitis capitata (Diptera: Tephritidae)

“…In all bioassays performed, adults of C. capitata were fed the toxic bait drops (40 μL) of the Success™ 0.02CB formulation, containing 96 mg L −1 of spinosad. This aspect is very important for the evaluation of the toxicity of formulations of toxic baits, as one of the main factors influencing the efficiency of the formulations is the phage-stimulating effect of the supplied material, which provides a greater or lesser attractiveness (Nestel et al 2004). Adults of C. capitata from larvae developed on artificial diet showed greater susceptibility to the Success™ 0.02CB toxic bait compared to insects from larvae developed in mango fruits, even though they had the same bait consumption.…”

“…For an ingestion experiment aimed at the evaluation of formulations of toxic baits, the longer the insect remains feeding and the greater the amount of food intake consumed, the greater the possibility of intoxication by the lethal agent and, consequently, the faster the effect of the product on the insect (Raga & Galdino 2018). Thus, the supply of another food source along with the toxic bait can reduce the consumption of the toxic bait and, consequently, the amount of lethal agent ingested by the insect (Nestel et al 2004, Raga & Galdino 2018. This fact may underestimate the lethal dose and the lethal time of the food attraction evaluated, especially if the insecticide does not present a knock-down effect, such as spinosad.…”