Synthesis and activity of 3-oxo-α-ionone analogs as male attractants for the solanaceous fruit fly, Bactrocera latifrons (Diptera: Tephritidae)

A series of 3-oxygenated α-ionone analogs have been developed as highly specific male lures for the solanaceous fruit fly Bactrocera latifrons, a pest of solanaceous fruits. We compared the attractant and phagostimulant activities of analogs with or without (i) unsaturations at the 4,5- and/or 7,8-positions and (ii) oxygen moieties at the 3- and/or 9-positions of the ionone molecule. Since naturally occurring vomifoliol (V2) was found to induce a highly potent phagostimulant activity in B. latifrons males, related analogs including, dehydrovomifoliol (V1), 6-hydroxy-α-ionone (U1) and 6-hydroxy-α-ionol (U2) were synthesized to evaluate their attractant and phagostimulant activities. Synthetic V1, V2, U1 and U2 exhibited low attractant activity, but their phagostimulant activity was relatively high. Optical isomers of 3-oxo-7,8-dihydro-α-ionone (P3) and V1 were prepared to examine the stereochemical specificity of attractants. (+)-(6R)-P3 and (+)-(6S)-V1 exhibited the corresponding activities, while their respective antipodal enantiomers were found entirely inactive.

Population genetics of the solanum fruit fly, Bactrocera latifrons (Hendel) (Diptera: Tephritidae)

The solanum fruit fly, Bactrocera latifrons (Hendel), is an important pest species of commercial plants in the family Solanaceae. In this study, the population genetic structure of B. latifrons was investigated using mitochondrial cytochrome c oxidase I sequences. A mitochondrial DNA haplotype network revealed no major genetic break, but haplotypes from recently invaded areas in Japan, Tanzania, and Kenya were genetically divergent. The overall haplotype network is approximately star-shaped, characteristic of recent demographic expansion of populations. This is also supported by large negative values of neutrality tests. Despite the overall pattern of recent population history, genetic structure analysis revealed considerable genetic structuring with 33% of pairwise comparisons being significantly different. Populations that were genetically different from the others usually possess low genetic diversity, suggesting that genetic drift is potentially a factor driving genetic differentiation. Local extinction and recolonization processes related to the availability of host plants are most likely responsible for a founder effect and subsequent genetic drift in a population.

Comparative Proteomic Profiling between Each of Two Consecutive Developmental Stages of the Solanum Fruit Fly, Bactrocera latifrons (Hendel)

The Solanum fruit fly, Bactrocera latifrons (Hendel), has a complex life cycle including multiple stages (egg, larva, pupa, and adult). Understanding the details of “what”, “when”, “where”, “why”, and “how” many hundred thousand proteins operate in this insect, interact, and express between each two consecutive developmental stages at molecular level not only can expand our knowledge, but also lead to the development of novel fruit fly control techniques. We tried to find what, when, and where in this study. Why and how will be presented in upcoming papers. We conducted a proteome profiling using 2-D gel electrophoresis and mass spectrometry. Samples of 3-day-old eggs, 1- and 10-day-old larvae, 1- and 10-day-old pupae, 1- and 9-day-old females and males of B. latifrons were used. A custom peptide database, derived from the de novo B. latifrons whole genome assembly was used for peptide identification. Differentially expressed proteins (DEPs) with significant fold expression and protein functions between two consecutive developmental stages were identified, annotated, described, and listed in gel images and/or charts. With this foundational information, we are not only providing valuable information, but also any impacts due to the biotic or abiotic environmental factors can be identified and manipulated, and lead to further research on gene editing and biomarker discovery.

Field Trapping Bactrocera latifrons (Diptera: Tephritidae) with Select Eugenol Analogs That Have Been Found to Attract Other 'Non-Responsive' Fruit Fly Species

Bactrocera latifrons (Hendel) (Diptera: Tephritidae) is a pest fruit fly species native to Oriental Asia which has invaded and established in Hawaii and Tanzania and has been recovered in detection trapping in California. It is largely non-responsive to the male lures cuelure and methyl eugenol. Alpha-ionol + cade oil is a moderately effective male B. latifrons attractant, but is not as attractive as cuelure or methyl eugenol are to other fruit fly species. An improved attractant is therefore desired. With the recent success in finding other non-responsive fruit fly species attracted to isoeugenol, methyl-isoeugenol, or dihydroeugenol in Australia and other countries, we wanted to assess whether B. latifrons might also respond to these “eugenol analogs.” Working with wild B. latifrons populations in Hawaii, we assessed the relative catch of B. latifrons in traps baited with the eugenol analogs with catch in traps baited with alpha-ionol, alpha-ionol + cade oil, or alpha-ionol + eugenol. Catch was significantly higher in traps baited with alpha-ionol + cade oil relative to traps with any of the other baits. There was, though, some male B. latifrons catch in traps baited with dihydroeugenol or isoeugenol but none in traps baited with methyl-isoeugenol.

Assessment of Navel Oranges, Clementine Tangerines, and Rutaceous Fruits as Hosts of Bactrocera cucurbitae and Bactrocera latifrons (Diptera: Tephritidae)

Export of Citrus spp. fruits may require risk mitigation measures if grown in areas with established tephritid fruit fly (Diptera: Tephritidae) populations capable of infesting the fruits. The host status of Citrus spp. fruits is unclear for two tephritid fruit fly species whose geographic ranges have expanded in recent years: melon fly, Bactrocera cucurbitae (Cocquillett), and Bactrocera latifrons (Hendel). In no choice cage infestation studies, B. latifrons oviposited into intact and punctured Washington navel oranges (Citrus sinensis [L.] Osbeck) and Clementine tangerines (C. reticulata L. var. Clementine), but eggs rarely developed to the adult stage. B. cucurbitae readily infested intact and punctured tangerines, and to a lesser extent punctured oranges, but did not infest intact oranges. Limited cage infestation and only a single literature report of field Citrus spp. infestation suggest that risk mitigation of Citrus spp. for B. latifrons is not needed. Risk mitigation options of Citrus spp. for B. cucurbitae, including heat and cold treatments and systems approaches, are discussed.