Marking Bactrocera dorsalis (Diptera: Tephritidae) with fluorescent pigments : effects of pigment colour and concentration

Daylight fluorescent pigment powders are frequently used to self-mark tephritid flies that are released in sterile insect technique programmes and for studies on their population ecology, movement and behaviour. This study was conducted to determine the effects of pigment colour and dose in marking the Oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae). Six pigment colours (Astral Pink 1, Blaze 5, Stellar Green 8, Lunar Yellow 27, Comet Blue 60 and Invisible Blue 70) were applied to pupae at doses of 0, 2, 4, or 6 g/l. Under laboratory conditions, pigment colour had a small but significant effect on the number of partially emerged and deformed adults; the fewest of these were observed when flies were marked with Astral Pink 1. Pigment concentration, on the other hand, had no effect on adult emergence, partial emergence, deformed adults and mortality on the last day of eclosion. There was no significant effect of pigment colour on adult survival under laboratory and semi-field conditions. Under laboratory conditions, however, there was an effect of pigment concentration on adult survival depending on pigment colour. Visibility under an ultraviolet light and persistence of marks was significantly affected by pigment colour and concentration when observed under laboratory conditions, but not under semi-field conditions. Regardless of colour or dose, pigments used in the study were visible for at least 14 days, but began to fade by 21 days after adult eclosion. To mark B. dorsalis under temperate, warmsummer African conditions, all pigment colours tested in this study may be applied at 2–4 g/l pupae. Recaptures ofmarkedandreleased fliesmaybe underestimated as the flies age.Citrus Research International (project 1075), Hortgro Science, and the South African Table Grape Industry as well as the The South African Government through its Technology and Human Resources for Industry Programme(THRIP; project TP1207132909).http://www.journals.co.za/content/journal/entohttp://www.entsocsa.co.za/Publications.htmam2017Zoology and Entomolog

Larval and adult diet affect phenotypic plasticity in thermal tolerance of the marula fly, Ceratitis cosyra (Walker) (Diptera : tephritidae)

DATA AVAILABILITY STATEMENT : The original contributions presented in the study are publicly available. This data can be found here: https://doi.org/10.25403/ UPresearchdata.22262965.INTRODUCTION : Temperature fluctuations are important for the distribution and survival of insects. Rapid hardening, a type of phenotypic plasticity, is an adaptation that can help individuals better tolerate lethal temperatures because of earlier exposure to a sublethal but stressful temperature. Nutrition and sex are also known to influence a species ability to tolerate thermal stress. This study determined the effects of larval diet, adult diet, sex and hardening on the thermal tolerance of Ceratitis cosyra (Walker) (Diptera: Tephritidae) at lower and upper lethal temperatures. METHODS : Larvae were raised on either an 8% torula yeast (high) or a 1% torula yeast (low) larval diet and then introduced to one of three dietary regimes as adults for thermal tolerance and hardening assays: no adult diet, sugar only, or sugar and hydrolysed yeast diet. Flies of known weight were then either heat- or cold-hardened for 2 hours before being exposed to a potentially lethal high or low temperature, respectively. RESULTS : Both nutrition and hardening as well as their interaction affected C. cosyra tolerance of stressful temperatures. However, this interaction was dependent on the type of stress, with nutrient restriction and possible adult dietary compensation resulting in improved cold temperature resistance only. DISCUSSION : The ability of the insect to both compensate for a low protein larval diet and undergo rapid cold hardening after a brief exposure to sublethal cold temperatures even when both the larva and the subsequent adult fed on low protein diets indicates that C. cosyra have a better chance of survival in environments with extreme temperature variability, particularly at low temperatures. However, there appears to be limitations to the ability of C. cosyra to cold harden and the species may be more at risk from long term chronic effects than from any exposure to acute thermal stress.Citrus Research International.https://www.frontiersin.org/journals/insect-scienceam2024Zoology and EntomologySDG-02:Zero HungerSDG-15:Life on lan

Effect of sex, age and morphological traits on tethered flight of Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) at different temperatures

The oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), is a pest of fruit and vegetable production that has become established in 42 countries in Africa after its first detection in 2003 in Kenya. It is likely that this rapid expansion is partly due to the reported strong capacity for flight by the pest. This study investigated the tethered flight performance of B. dorsalis over a range of constant temperatures in relation to sex and age. Tethered flight of unmated B. dorsalis aged 3, 10 and 21 days was recorded for 1 h using a computerized flight mill at temperatures of 12, 16, 20, 24, 28, 32 and 36 °C. Variations in fly morphology were observed as they aged. Body mass and wing loading increased with age, whereas wing length and wing area reduced as flies aged. Females had slightly larger wings than males but were not significantly heavier. The longest total distance flown by B. dorsalis in 1 h was 1559.58 m. Frequent short, fast flights were recorded at 12 and 36 °C, but long‐distance flight was optimal between 20 and 24 °C. Young flies tended to have shorter flight bouts than older flies, which was associated with them flying shorter distances. Heavier flies with greater wing loading flew further than lighter flies. Flight distances recorded on flight mills approximated those recorded in the field, and tethered flight patterns suggest a need to factor temperature into the interpretation of trap captures.Citrus Research International; Hortgro Science; South African Table Grape Industry and National Research Foundation.https://onlinelibrary.wiley.com/journal/136530322021-05-20hj2021Zoology and Entomolog

Distribution and host ranges of Ceratitis rosa and Ceratitis quilicii (Diptera: Tephritidae) in South Africa

The original publication is available at: https://www.cambridge.org/Two fruit fly (Diptera: Tephritidae) species of economic importance: Ceratitis rosa Karsch and Ceratitis quilicii De Meyer, Mwatawala & Virgilio are present in South Africa. The two species were considered as one species prior to 2016, but were subsequently separated. In this study, the distribution and abundance of the two species were quantified in seven provinces in South Africa through trapping with Enriched Ginger Oil as an attractant. Trapping was conducted over three seasons across two years (2020 and 2021): late summer, autumn-winter, and spring-early summer. Host ranges of the two species were investigated by fruit sampling in and outside of trapping sites. Ceratitis quilicii was more widely distributed than C. rosa with the latter being recorded in only three north-eastern provinces. There were geographical limits for both species with no records of them in Northern Cape Province. Catches of C. quilicii were higher in summer with average temperatures varying from 15 to 27°C while for C. rosa, catches remained low and consistent between seasons. Ceratitis quilicii catches decreased at lower rates than those of C. rosa at temperatures below 15°C. The two species were reared from 13 plant species from nine families. Four of these hosts were infested by both C. quilicii and C. rosa in the same province where they occurred. Preferred hosts of the two species belonged to the Myrtaceae family. The characterisation of the distribution, abundance and host ranges of these pests will provide a baseline for pest status determination and implementation of management actions.https://www.cambridge.org/core/journals/bulletin-of-entomological-research/articlePublisher’s versio

Non-host status of commercial export grade lemon fruit (Citrus limon (L.) Burman f. cv. Eureka) for ceratitis capitata, ceratitis rosa, ceratitis quilicii and bactrocera dorsalis (Diptera: Tephritidae) in South Africa

Markets importing citrus fruit including lemons, Citrus limon (L.) Burman f., from South Africa require that the fruit be free of fruit fly pests (Diptera: Tephritidae). Historically there has been no fruit fly infestation recorded on lemons destined for export from SouthAfrica. In this study, we assessed the host status of commercial export grade Eureka lemons, Citrus limon (L.) Burmanf. cv. Eureka, for four fruit fly pest species of economic importance in South Africa: Ceratitis capitata (Wiedemann), Ceratitis rosa Karsch, Ceratitis quilicii De Meyer, Mwatawala & Virgilio, and Bactrocera dorsalis (Hendel). Trapping was conducted in 10 Eureka lemon orchards in two major citrus production regions over two citrus seasons between 2016 and 2017 to determine the level of fruit fly abundance in the sampled orchards. Lemons were collected at harvest over the two seasons in the same orchards where trapping was conducted. Fruit fly infestation of the sampled lemons was determined by dissection. Additionally, infestation of lemons was determined under forced exposure to mature mated females of C. capitata and B. dorsalis. Trapping data showed the presence of adults of all four fruit fly species in the sampled lemon orchards.Nofruit fly infestation was detected in 43 222 Eureka lemons sampled at harvest. There was also no infestation of lemons under forced exposure conditions. The results of this study provide evidence with 99.99 % efficacy and a 99%confidence level that SouthAfrican commercial export grade Eureka lemon fruit is not a host for C. capitata, C. rosa, C. quilicii or B. dorsalis.http://www.journals.co.za/content/journal/entohttp://www.bioone.org/loi/afen2020-03-01am2018Zoology and Entomolog

DNA barcoding further indicates cryptic genetic variation in the mangao fruit fly, Ceratitis cosyra (Diptera, Tephritidae)

The mango fruit fly, Ceratitis cosyra, is a major agricultural pest affecting mango production in sub-Saharan Africa. Morphological differences between C. cosyra and four closely related Ceratitis (Ceratalaspis) species (C. discussa, C. quinaria, C. silvestrii, C. striatella) are subtle, so that reliable separation often requires specialized expertise. Additionally, a previous study showed cryptic genetic variation in C. cosyra with microsatellite genotypic clusters also occurring in sympatry. DNA barcoding further supported cryptic genetic variation in C. cosyra due to outlier DNA sequences. This study aimed to verify whether DNA barcoding can profitably be used to (a) resolve the two main microsatellite genotypic clusters of C. cosyra, and (b) separate C. cosyra from C. discussa, C. quinaria, C. silvestrii, and C. striatella. A subset of 48 C. cosyra specimens previously assigned to the two microsatellite genotypic clusters was subjected to DNA barcoding. This dataset was integrated with 83 public DNA barcodes of C. cosyra, C. discussa, C. quinaria, C. silvestrii, and C. striatella from the Barcode of Life Data Systems (BOLD). Neighbour joining tree (K2P distance) separated the two C. cosyra genotypic clusters and also resolved properly supported groups corresponding to (a) C. quinaria and C. silvestrii, (b) C. discussa (only 2 specimens considered) and possibly (c) C. striatella (all specimens but one included in the same clade). These results further support the hypothesis of cryptic speciation in the mango fruit fly and suggest that DNA barcoding represents a suitable tool for the identification of C. cosyra and of the closely related Ceratitis (Ceratalaspis) species. (Texte intégral

A new genome sequence resource for five invasive fruit flies of agricultural concern: Ceratitis capitata, C. quilicii, C. rosa, Zeugodacus cucurbitae and Bactrocera zonata (Diptera, Tephritidae)

Here, we present novel high quality genome assemblies for five invasive tephritid species of agricultural concern: Ceratitis capitata, C. quilicii, C. rosa, Zeugodacus cucurbitae and Bactrocera zonata (read depths between 65 and 78x). Three assemblies (C. capitata, C. quilicii and Z. cucurbitae) were scaffolded with chromosome conformation data and annotated using RNAseq reads. For some species this is the first reference genome available (B. zonata, C. quilicii and C. rosa), for others we have published improved annotated genomes (C. capitata and Z. cucurbitae). Together, the new references provide an important resource to advance research on genetic techniques for population control, develop rapid species identification methods, and explore eco-evolutionary studies

Global strategies to manage huanglongbing (HLB) and its vectors: insights and implications for the Mediterranean region

Huanglongbing (HLB), also known as citrus greening disease, poses a severe threat to the global citrus industry. This disease is caused by three species of bacteria, ‘Candidatus Liberibacter asiaticus’, ‘C. L. africanus’, and ‘C. L. americanus’. The primary pathogen vectors are the Asian citrus psyllid (Diaphorina citri Kuwayama, Hemiptera: Psyllidae) and the African citrus psyllid (Trioza erytreae Del Guercio, Hemiptera: Triozidae). The disease is incurable, and its management relies on reducing vector densities and the adverse effects of bacterial infections on host trees. Managing psyllid vectors, especially D. citri, has proven exceptionally challenging due to its rapid spread and subsequent difficulty in containing and suppressing newly detected populations. This article reviews strategies developed to manage HLB and its vectors in different regions of the world with a focus on the challenges likely to be faced by the Mediterranean region. Diaphorina citri has recently invaded the Mediterranean region and T. erytreae has been encroaching via the northern Iberian Peninsula for several years. Currently, HLB has not been detected in this important citrus production area. Therefore, this area must implement preventive measures and proactively prepare for potential invasions by D. citri, T. erytreae, and HLB-causing pathogens by developing and adopting comprehensive management strategies in advance of anticipated invasion events