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Cuelure, an effective lure specifically targeting Tephritid fruit flies, has been widely adopted and applied in the monitoring and control of these pests, providing significant support for agricultural pest management. However, its uncontrollable release speed and duration usually lead to a lot of waste, diminishing its effectiveness and increasing the cost of pest control. In order to solve these problems, we focused on Zeugodacus cucurbitae Coquillett and developed a temperature-sensitive nano-controlled release agent for cuelure. The release rate of this agent can be adjusted by adjusting the ambient temperature. The results show that the temperature-sensitive cuelure nano-controlled release agent demonstrates remarkable temperature-responsive controlled release characteristics. It still exhibits exceptional stability even after being subjected to high-temperature treatment at 60 °C for a week, and the trapping efficiency of this attractant remains between 73% and 75%. This study not only holds immense practical value in monitoring, warning, and managing of fruit fly pests, but it also lays a novel theoretical foundation for the development of insect attractants.

Zeugodacus cucurbitae (Coquillett) is a significant pest affecting fruit and vegetables in tropical and subtropical regions, and its development and reproduction are enhanced after exposure to short-term high-temperature stress at 45 °C. Vitellogenin (Vg) is an essential precursor of yolk protein formation in eggs and plays a vital role in the ovarian development of insects. Interfering with the Z. cucurbitae vitellogenin receptor (ZcVgR) gene in short-term high-temperature conditions decreases the fecundity of female adults, while the transcription level of the ZcVg3 gene increases. To elucidate the reproductive function of the ZcVg3 gene and the synergistic relationship among the ZcVgs genes under short-term high temperatures, this study injected siRNA to interfere with the ZcVg3 gene after subjecting Z. cucurbitae to a 1 h treatment at 45 °C and 25 °C. The expression of the ZcVg3 gene was suppressed, leading to the upregulation of the ZcVg1 and ZcVg2 genes, and the expression of the ZcVgR gene was initially decreased and then increased. Silencing the ZcVg3 gene after a 1 h treatment at 45 °C resulted in a reduction of approximately 84.7% and 75.9% in the fecundity and spawning days of female adults compared to the control. The development rate of their ovaries and the ovarian diameter significantly decreased, and their lifespan was reduced by 71%. The ZcVg3 gene plays a crucial role in the reproduction of Z. cucurbitae in short-term high-temperature conditions. The results of this study provide potential targets for the development of RNAi-based techniques for the control of Z. cucurbitae.

Tephritid fruit flies, such as the melon fly, Zeugodacus cucurbitae , are major horticultural pests worldwide and pose invasion risks due primarily to international trade. Determining movement parameters for fruit flies is critical to effective surveillance and control strategies, from setting quarantine boundaries after incursions to development of agent-based models for management. While mark-release-recapture, flight mills, and visual observations have been used to study tephritid movement, none of these techniques give a full picture of fruit fly movement in nature. Tracking tagged flies offers an alternative method which has the potential to observe individual fly movements in the field, mirroring studies conducted by ecologists on larger animals. In this study, harmonic radar (HR) tags were fabricated using superelastic nitinol wire which is light (tags weighed less than 1 mg), flexible, and does not tangle. Flight tests with wild melon flies showed no obvious adverse effects of HR tag attachment. Subsequent experiments successfully tracked HR tagged flies in large field cages, a papaya field, and open parkland. Unexpectedly, a majority of tagged flies showed strong flight directional biases with these biases varying between flies, similar to what has been observed in the migratory butterfly Pieris brassicae . In field cage experiments, 30 of the 36 flies observed (83%) showed directionally biased flights while similar biases were observed in roughly half the flies tracked in a papaya field. Turning angles from both cage and field experiments were non-random and indicate a strong bias toward continued “forward” movement. At least some of the observed direction bias can be explained by wind direction with a correlation observed between collective melon fly flight directions in field cage, papaya field, and open field experiments. However, individual mean flight directions coincided with the observed wind direction for only 9 out of the 25 flies in the cage experiment and half of the flies in the papaya field, suggesting wind is unlikely to be the only factor affecting flight direction. Individual flight distances (meters per flight) differed between the field cage, papaya field, and open field experiments with longer mean step-distances observed in the open field. Data on flight directionality and step-distances determined in this study might assist in the development of more effective control and better parametrize models of pest tephritid fruit fly movement.

This paper reviews all available information regarding the occurrence and biology of the melon fly, Zeugodacus cucurbitae (Coquillett), in the Afrotropical Region, including data on invasion history, distribution patterns, population genetics, host range, and interspecific competition. Although limited intraspecific variability has been observed within the region regarding the above mentioned aspects, there seems to be no indication that Zeugodacus cucurbitae represents a species complex. A checklist of all of the species included in Zeugodacus as recently proposed by Virgilio et al. (2015) is provided.

The fruit flies Bactrocera tau (Walker) and B. cucurbitae (Coquillett) are economically important invasive pests on numerous vegetable and fruit species in China. Due to the instability of the early spring climate, temperatures often deviate far below the normal temperature for short periods of time. Such a sudden short-term low temperature may impact the reproduction and development of the two fruit fly species. In this study, the effects of low temperatures (8, 6, 4, 2, 0, –2, and –4°C) on the development and reproduction of these two closely related fruit fly species were studied under laboratory condition. The results showed that their survival rates decreased gradually with corresponding decreases in the tested temperatures. On the other hand, their pre-oviposition periods and their adult female to male sex ratios increased, while the average number of eggs per female of each species and longevity of male adult of B. cucurbitae initially increased and later decreased after exposure to the low-temperature treatments. Overall, low temperatures promoted reproduction in B. cucurbitae and B. tau at temperatures ranging from 24°C to as low as 8°C. Development and reproduction of the two species were negatively affected when temperatures were between 8 to –4°C. The cold resistance of each developmental stage was higher in B. tau than in corresponding stages of B. cucurbitae.

Zeugodacus cucurbitae and Z. tau are two major fruit fly pests of cucurbitaceous plants in the tropical and subtropical regions. The former species has a broader host range and wider world distribution than the latter. With global climate change, Z. tau shows great potential for geographical expansion with several invasion records in recent years. Males of both species are attracted to cue lure (CL) (and raspberry ketone (RK), a deacetyl derivative of CL), a common male lure used in fruit fly population detection, monitoring and control programs. Males of both species are also known to respond to zingerone (ZN), which are produced by some rainforest orchids. Previous studies have shown that fruit fly-male lure interactions are unique to species and lure types, and significantly impact the success of a lure-based fruit fly control program. We seek to compare the attraction of Z. cucurbitae and Z. tau males to CL, RK and ZN via Probit behavioral assays. Our results showed that CL is more attractive to Z. cucurbitae and Z. tau males than RK, while ZN is a poor lure for both species. Attraction Z. tau to CL is slightly lower than Z. cucurbitae, but the former is at least 1.71 times less attractive to RK than the latter. Together with published information on species’ sexual development, our current study indicates a lure-based control program via male annihilation technique for Z. tau will be more challenging than Z. cucurbitae and should incorporate other integrated pest management strategies for a desirable outcome.

Tephritid fruit flies are major economic pests for fruit production and are an impediment to international trade. Different host fruits are known to vary in their suitability for fruit flies to complete their life cycle. Currently, international regulatory standards that define the likely legal host status for tephritid fruit flies categorize fruits as a natural host, a conditional host, or a nonhost. For those fruits that are natural or conditional hosts, infestation rate can vary as a spectrum ranging from highly attractive fruits supporting large numbers of fruit flies to very poor hosts supporting low numbers. Here, we propose a Host Suitability Index (HSI), which divides the host status of natural and conditional hosts into five categories based on the log infestation rate (number of flies per kilogram of fruit) ranging from very poor (<0.1), poor (0.1–1.0), moderately good (1.0–10.0), good (10–100), and very good (>100). Infestation rates may be determined by field sampling or cage infestation studies. We illustrate the concept of this index using 21 papers that examine the host status of fruits in five species of polyphagous fruit flies in the Pacific region: Bactrocera tryoni Froggatt, Bactrocera dorsalis (Hendel), Bactrocera latifrons (Hendel), Zeugodacus cucurbitae (Coquillett), and Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). This general-purpose index may be useful in developing systems approaches that rely on poor host status, for determining surveillance and detection protocols for potential incursions, and to guide the appropriate regulatory response during fruit fly outbreaks.

The melon fruit fly, Bactrocera cucurbitae (Coquillett) and the pumpkin fruit fly, Bactrocera tau (Walker) (Diptera: Tephritidae), are important invasive pests on Cucurbitaceous hosts. The acute toxicity of five insecticides to females of these two fruit fly species was bio-assayed by membrane method, and effects of their sublethal concentration on the survival, reproduction, and ovary development of females were evaluated in the laboratory. Results showed that based on the LC50 values, both B. cucurbitae and B. tau were the most susceptible to trichlorfon. After treatment with sublethal concentration (LC30) of trichlorfon, abamectin+β-cypermethrin, spinetoram, and lambda-cyhalothrin, the female survival days of the two Bactrocera species were significantly shortened compared with the control. Moreover, the fecundity of two Bactrocera species was remarkably decreased, after exposure to abamectin+β-cypermethrin and trichlorfon LC30. However, the sublethal concentration (LC30) of insecticides had no significant influence on the egg hatchability of the fruit flies. Furthermore, after treatment with abamectin+β-cypermethrin LC30, the ovary length, width, and egg load of B. cucurbitae were significantly lower than that of the control; however, only the ovarian length and egg load of B. tau were significantly decreased on the 16th and 20th day. In conclusion, abamectin+β-cypermethrin has an excellent insecticidal activity against B. cucurbitae and B. tau.

Fruit flies attack numerous crops, including cherry tomatoes (Solanum lycopersicum var. cerasiforme). The potential presence of the immature stages of fruit fly species inside tomatoes during export hinders their international market access. Therefore, phytosanitary treatment must be performed before export to prevent fruit fly species from entering countries where they are not naturally found. We developed a phytosanitary cold disinfestation treatment protocol to eliminate oriental fruit fly (Bactrocera dorsalis Hendel), melon fly (Zeugodacus cucurbitae Coquillett), and pumpkin fruit fly (Zeugodacus tau Walker) concealed inside cherry tomatoes without causing critical damage to the fruit. We determined that the third instar of Z. cucurbitae exhibited the highest cold tolerance among the various development stages of the three fruit fly species.Thus, we performed a small-scale disinfestation test on Z. cucurbitae in two cultivars of tomato. We achieved complete disinfestation after 15 days of cold treatment at 1°C–1.5°C.The confirmatory test revealed the elimination of more than 80,000 treated third instar of Z. cucurbitae in each tomato variety.The developed phytosanitary cold treatment allows the tomatoes to retain their commercial value.This study provides a standard phytosanitary cold treatment protocol for cherry tomatoes, ensuring the disinfestation of fruit flies before their export to international markets. Graphical Abstract

γ-Terpinene, a monoterpene widely present in essential oils of many medicinal and aromatic plants with numerous biological properties, was evaluated for its insecticidal activity against melon fruit fly, Zeugodacus cucurbitae (Coquillett). Different concentrations (5, 25, 125, 625, and 3125 ppm) of γ-terpinene along with control were fed to larvae of melon fly. The number of pupae formed and adults emerged declined significantly after treatment. Morphologically deformed adults and pupae were also observed. The developmental duration too prolonged in treated larvae. Food assimilated, mean relative growth rate, larval weight gain, and pupal weight also declined. In the larvae treated with LC 30 and LC 50 concentrations, there was a decline in the titers of phenoloxidase and total hemocyte count, and variations were observed in the differential hemocyte count, suggesting an immunosuppressive effect of γ-terpinene on melon fly. Both concentrations also led to an increase in the apoptotic and necrotic cells as well as decrease in the viable hemocytes in the circulating hemolymph of treated larvae. Comet parameters (tail length, % tail DNA, tail moment, and olive tail moment) of γ-terpinene fed larvae increased significantly. Given the observed effects of γ-terpinene on normal developmental and nutritional physiology, its immunosuppressive properties, and its potential for genome damage, it can be considered for incorporation into integrated pest management strategies for controlling Z. cucurbitae .