Zingerone improves mating performance of Zeugodacus tau (Diptera: Tephritidae) through enhancement of male courtship activity and sexual signaling

A review on natural phenylbutanoid attractants: Occurrence, distribution, and role in nature, especially in relation to Dacini fruit fly behavior and pollination

The natural occurrence, distribution (within a plant) and roles of four phenylbutanoid compounds (anisyl acetone, cue-lure, raspberry ketone and zingerone) are elucidated for the Asia-Pacific and Oceania regions. These phenylbutanoids may act individually or in combination to attract true fruit fly males belonging to a tribe Dacini of subfamily Dacinae (Diptera: Tepritidae). Of special interest are the mutualistic interactions between the Dacini fruit fly males and the tropical daciniphilous (attracting exclusively Dacini fruit flies) orchids - leading to cross pollination for the orchids and enchanced mating success for the flies. When offered to male flies, anisyl acetone and cue-lure are generally converted to raspberry ketone. Upon consumption, raspberry ketone and zingerone are individually sequestered in the male rectal (pheromonal) gland unchanged. Attracted male flies readily imbibe the phenylbutanoid(s) in the floral synomone to compliment the endogenously synthesized male sex pheromonal components - to enhance attraction of conspecific females during courtship as well as attract conspecific males to form 'leks'. The phenylbutanoid(s) may also act as an allomone to deter vertebrate predators, especially geckos, besides possessing antimicrobial and antioxidant activities. Cue-lure, raspberry ketone and zingerone are important attractants/lures used in pest surveillance and mass trapping under the integrated pest management (IPM) program against quarantine Dacini fruit fly pest species, particularly Bactrocera tryoni and Zeugodacus cucurbitae.

Reproductive behavior of fruit flies: courtship, mating, and oviposition

Many species of the Tephritidae family are invasive and cause huge damage to agriculture and horticulture, owing to their reproductive characteristics. In this review, we have summarized the existing studies on the reproductive behavior of Tephritidae, particularly those regarding the genes and external factors that are associated with courtship, mating, and oviposition. Furthermore, we outline the issues that still need to be addressed in fruit fly reproduction research. The review highlights the implications for understanding the reproductive behavior of fruit flies and discusses methods for their integrated management and biological control. © 2023 Society of Chemical Industry.

The Effect of Cuelure on Attracting and Feeding Behavior in Zeugodacus tau (Walker) (Diptera: Tephritidae)

As a vital pest control strategy, trapping plays an important role in the system of monitoring, catching and killing fruit flies. Cuelure (4-(4-acetoxyphenyl)-2-butanone, CL) is a male lure that attracts Zeugodacus tau and also stimulates feeding in this species. In this study, the attraction of Z. tau to CL and its subsequent feeding behavior were investigated. Under the significant influence of age and time of day, the attraction of CL to Z. tau was found to be optimal when flies were 14 days old, and the number of flies trapped increased with trapping duration. It was determined that consumption can improve the mating success and female adult fertility of Z. tau. After the observation period, the mating success rate of flies that ingested CL was significantly higher than that of the control group and was maintained at a higher level. It was found that parental consumption of CL could accelerate the development of eggs and larvae, resulting in increased pupation and emergence rates. The results of this study will further clarify the dynamic relationship between pest and lure, and provide a research basis for navigating the integrated management of Z. tau in the field.

Evaluation of the Attractant Effect of Solanum muricatum (Solanales: Solanaceae) on Gravid Female Adults of Zeugodacus tau (Diptera: Tephritidae) and Screening of Attractant Volatiles

Zeugodacus tau (Walker) (Diptera: Tephritidae) is a pest seriously harmful to Solanaceae crops and was found to oviposit on the pepino melon Solanum muricatum (Aiton). To date, the differences in the ability of the fruits of S. muricatum and other Solanaceae crops to attract gravid Z. tau females have seldom been reported. Oviposition and trapping bioassays were performed to clarify whether such differences existed. A combination of GC-MS and the Y-tube olfactometer system was used to identify and determine the compounds inducing behavioral responses in gravid Z. tau females to the volatile odors of S. muricatum. The results show that S. muricatum odors play a role in attracting gravid Z. tau females. The odors of Solanaceae crops influence their ability to attract these organisms. The nine compounds from the volatiles of S. muricatum induce tendency or repellency responses in gravid Z. tau females. Hexyl acetate, butyl acetate, amyl actate, and isoamyl acetate caused tendency behavior in gravid Z. tau females, while hexyl hexanoate, butyl isovalerate, butyl valerate, and isoamyl hexanoate caused repellency behavior. Heptyl acetate caused repellency behavior in gravid Z. tau females at higher concentrations (5 mg/mL) but caused tendency behavior at a low concentration (0.5 mg/mL). These results suggest that vigilance against the harm caused by Z. tau is required during the cultivation of S. muricatum. The nine compounds of the volatile odors of S. muricatum could help to develop attractants and repellents for gravid Z. tau females. These results are beneficial for preventing Z. tau females from harming S. muricatum, developing attractants and repellents for Z. tau females, and establishing a system of ecological control for Z. tau females.

Effect of short-term exposure to high temperatures on the reproductive behavior and physiological enzyme activities in the fruit fly Zeugodacus tau (Walker)

Zeugodacus tau is an economically important invasive pest of various vegetables and fruits. In this study, we evaluated the effects of short-term (12 h) exposure to high temperatures on the reproductive behaviors and physiological enzyme activities of adult Z. tau flies. When compared to the control group, the mating rate in the treated group increased significantly after exposure to 34°C and 38°C. After 34°C exposure, the mating rate of the control♀-treated♂ mating was the highest (60.0%). The use of high temperatures for a short period reduced the pre-mating period and lengthened the duration of copulation. After 38°C exposure, the mating between treated♀ and treated♂ had the shortest pre-mating period of 39.0 min and the longest copulation duration of 67.8 min. Mating after a brief exposure to high temperatures had a negative impact on female reproduction, whereas mating with males who previously had a brief exposure to 34°C and 38°C significantly increased female fecundity. After 40 °C exposure, the mating between treated♀ and control♂ showed the lowest fecundity and hatching rate of 293.25 eggs and 25.71%, respectively. The mating between control♀ and treated♂ showed the highest fecundity of 1,016.75 eggs after exposure to 38°C. The SOD, POD, and CAT activities exhibited significant changes (increase or decrease) after the short-term exposure of Z. tau adults to high temperatures. After being exposed to 38°C, SOD activity increased by 2.64 and 2.10 times in females and males in the treated group, respectively, compared to the SOD activity in the control group. The AchE, CarE, and GST activities first increased and then decreased with the increase in temperature. CarE activity changed the most after exposure to 38°C, with females and males in the treated group increasing by 7.81 and 1.69 times, respectively, compared to the activity in the control group. In conclusion, mating strategy and physiological stress are important adaptive mechanisms of Z. tau for adapting to short-term heat stress in a sex-specific manner.

Toxics or Lures? Biological and Behavioral Effects of Plant Essential Oils on Tephritidae Fruit Flies

The family Tephritidae (Diptera) includes species that are highly invasive and harmful to crops. Due to globalization, international trade, and human displacement, their spread is continuously increasing. Unfortunately, the control of tephritid flies is still closely linked to the use of synthetic insecticides, which are responsible for detrimental effects on the environment and human health. Recently, research is looking for alternative and more eco-friendly tools to be adopted in Integrated Pest Management (IPM) programs. In this regard, essential oils (EOs) and their main compounds represent a promising alternative to chemical insecticides. EOs are made up of phytoconstituents formed from the secondary metabolism of many plants and can act as attractants or toxics, depending on the dose. Because of this unique characteristic, EOs and their main constituents are promising tools that can be used both in Sterile Insect Technique (SIT) programs and in the "lure and kill" technique, exploiting the attractiveness of the product in the former case and its toxicity in the latter. In this article, current knowledge on the biological and behavioral effects of EOs and their main constituents on tephritid fruit flies is reviewed, mainly focusing on species belonging to the Anastrepha, Bactrocera, Ceratitis, and Zeugodacus genera. The mechanisms of action of EOs, their real-world applications, and challenges related to their use in IPM are critically discussed.

Male-lure type, lure dosage, and fly age at feeding all influence male mating success in Jarvis' fruit fly

Males of certain Dacini fruit flies are strongly attracted to, and feed upon, plant secondary compounds such as methyl eugenol, raspberry ketone and zingerone. The consumed lure is generally found to induce physiological and behavioural changes that enhance the mating performance of lure-fed males. Male Bactrocera jarvisi respond strongly to zingerone from a young age, but only weakly respond to raspberry ketone. We hypothesized that this selective lure-response would be reflected in the physiological importance of the lure to the fly. We found that zingerone feeding by young males resulted in significantly greater mating success in competitive mating trials with lure-deprived flies, but the mating advantage was lost in older males. Lure dosage had a significant effect on the duration of the mating advantage, for example when fed 20 µg of zingerone, the advantage lasted only 1 day post-feeding, but when fed of 50 µg zingerone the advantage lasted 7 days. Raspberry ketone feeding did not confer any mating advantage to males except at one dosage (50 µg) for 1 day after feeding. When given a choice, B. jarvisi females preferred to mate with zingerone-fed versus to raspberry ketone-fed males. This study revealed lure, dosage and age of fly at time of lure administration are all important factors for maximising lure-enhanced fruit fly mating performance. These findings contribute to a better theoretical understanding of the evolution of fruit fly-lure interactions and may help improve fruit fly pest management via the Sterile Insect Technique through semiochemical-mediated enhancement of sterile male mating performance.