Curative Activity of Insecticides on <I>Rhagoletis pomonella</I> (Diptera: Tephritidae) in Apples

Abstract

Field-based experiments were used to determine the lethal activity of insecticides on apple maggot, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae), eggs and larvae in apple (Malis spp.) fruit. The organophosphates azinphosmethyl and phosmet and the neonicotinoids thiacloprid, acetamiprid, clothianidin, and thiamethoxam showed significant curative activity on the apple maggot postinfestation, when applied topically to apple fruit 24 h postharvest. Of the compounds tested, only phosmet showed significant curative activity on apple maggot when applied 14 d postharvest. The pyrethroid esfenvalerate, oxadiazine indoxacarb, anthranilic diamide chlorantraniliprole, and spinosyns spinosad and spinetoram did not show activity on apple maggot eggs and larvae in fruit. Residue profiles showed that for most compounds, the majority (>85%) of residues were found in the skin and the outside 2 mm of the apple flesh. For the neonicotinoid compounds, however, substantial portions of residues were found to penetrate in and beyond the outer flesh regions, and the total flesh residue recoveries were generally greater than those from the skin. Residues of azinphosmethyl and phosmet were detected in all three flesh regions, with the largest proportions recovered from the skin.

Penetrative and Dislodgeable Residue Characteristics of 14C-Insecticides in Apple Fruit

“…14,32 In one field study on late season apples, thiacloprid showed higher proportions of penetrated residues in the inside-to-core section of hypanthium, resulting in greater curative activity on apple maggot, Rhagoletis pomonella (Walsh), larvae post-infestation. 14 The incidence of indoxacarb residues in apples were shown to be more concentrated in the cuticle and outside 2 mm of hypanthium adjacent to the cuticle. Several field studies have shown thiamethoxam fruit penetration to be more limited, especially when high-performance liquid chromatography (HPLC) detection excluded data associated with clothianidan as a metabolic byproduct.…”

“…Each fraction of water and methanol was separately transferred to a scintillation vial for radioactivity quantification. After the washed cores were dried at room temperature, razor blades were used to separate apple core samples into segments: the apple cuticle, outside 2 mm of hypanthium, next 2 mm of hypanthium, center 4 mm of hypanthium, and the remaining 8 ± 2 mm to the seed cavity (modified from ref 14). Blades were cleaned with acetone after each cut.…”

“…However, compounds that show curative activity on a pest on early season apples do not necessarily maintain the same effects on late season apple pests or the same pest in another fruit crop, such as cherries. 14,15 The plant cuticle, subtending the epicuticular wax, is a nonliving and non-uniform plant structure, made of a polymeric cutin matrix and soluble waxes, that protects the plant from water loss, is a barrier against pathogens, and allows for gas exchange. 16,17 The cuticle outer surface or extracellular membrane is composed of cutin and waxes, whereas the layer underneath contains polar polysaccharides and small amounts of cellulose and pectins.…”

Mechanism and effectiveness of safflower oil against female Queensland fruit fly Bactrocera tryoni

“…In addition to direct (topical) exposure, cover spray may kill flies through tarsal contact and/or ingestion of residue (Yee & Alston, ). Another advantage of some chemical cover sprays is that they can kill eggs and larvae in the infested fruits, though this effect depends not only on toxic but also on penetrative properties of the insecticides (Wise et al., ). Nevertheless, alternative methods to control fruit flies are required due to recent and future restrictions on these chemicals.…”

Comparative Efficacy of Insecticides on Bactrocera tryoni and Zeugodacus cucumis (Diptera: Tephritidae) in Laboratory and Semifield Trials in Fruiting Vegetables

“…A number of studies have examined the toxicity of pesticides to tephritid fruit flies in the laboratory using a range of methods such as direct application to adult flies (Wang et al 2013), exposure to residues on artificial substrates (Mosleh et al 2011), exposure to residues on fruit applied and aged in the laboratory (Maklakov et al 2001, Yee 2008, Yee and Alston 2012 or the field (Yee et al 2007, Rahman andBroughton 2016), or application of insecticide sprays to infested fruit (Wise et al 2009). Small plot field trials have been employed to assess efficacy of insecticides for management of cucurbit-specific fruit flies such as Z. cucurbitae in cucurbits (Oke 2008, Khursheed and Raj 2012, Oke and Sinon 2013, and field trials conducted in tree crops for management of Rhagoletis spp.…”