Fruit flies pose a significant threat to a wide range of agricultural crops due to their highly invasive nature. Key species of economic importance include Ceratitis capitata, Bactrocera zonata, Bactrocera cucurbitae and Drosophila suzukii.
The majority of the fruit fly species are highly polyphagous attacking multiple important fruits and vegetables. Female fruit flies deposit their eggs under the skin of fruits which result in direct losses. The resulting larvae will feed on the decaying flesh of the fruit in which they hatched. Infested fruits and vegetables quickly rot and become inedible or fall to the ground.
In addition to the direct damage caused to the plant, indirect losses to the horticultural industry can occur due to quarantine restrictions preventing the free trade and export of fresh horticultural produce to large lucrative markets abroad due to the risk of the fruit fly being transported with the produce.
In sub-Saharan Africa and South East Asia, the economic loss of tropical fruit and vegetable production due to fruit fly damage is estimated at hundreds of millions of dollars. Moreover, the possibility of introduction of invasive fruit flies species to fruit fly-free countries is one of the reasons why potential export opportunity has often failed to establish for fruit and vegetable growers from tropical and subtropical countries.
The cost of disinfestations is significantly high, ranging from 250-375 USD/ton subject to variety of fruits and vegetable. Traditional fruit fly control involves the spraying of chemical pesticide which is known to have a negative impact on the environment, the farmers and potentially the consumer. In addition, many species of fruit fly are developing resistance to conventional chemical insecticides.
Attract and Kill Technique
One of the most effective fruit fly control strategies is based on application of Male Annihilation Technique (MAT) to kill males and use of attract and kill systems for females. Russell IPM product Zonatrac and Ceranock attract and kill systems that target a range of Fruit Fly species.
The use of male and female attractant based attract and kill could provide more environmentally safe ways of controlling fruit fly species by manipulating the behaviour of male and female flies.
Russell IPM conducted field trials to determine the efficacy of its male and female attract and kill systems for the control of Bactrocera zonata (Figure 1a). This fruit fly is a serious pest in the mango orchards of Egypt and Libya. Mature fruits are most vulnerable to infestation and damage which leads to yield losses of up to 30-45% (Figure 1b).
MATERIALS AND METHODS
The Ceranock female and Zonatrac male attract and kill systems were applied together on 3 mango orchards for the control Bactrocera zonata. Treatment Plots are considered as Plot A, Plot B and untreated plot was considered as Control Plot. Ceranock, a ttract and kill system (Figure 2a) is an innovative bait station containing a protein based female attractant, plant extract and low dose toxicant Alpha-cypermethrin (0.2%) for the control of adult female flies. A total of 400 Ceranock bait stations were applied in every hectare inside the mango orchard, as one bait station on each tree at distance of four meters apart from each other.
Zonatrac male attract and kill system (Figure 2b) is an emulsified wax formulation containing Methyl Eugenol and a low dose insecticide. The formulation targets males of B. zonata to significantly reduce number of male flies. Zonatrac was applied on the field margin as well as on tree trunks or branches.
The study utilised just one application of both male and female attract and kill system as this is sufficient to cover the entire cropping season. Application of Ceranock and Zonatrac was made 6-8 weeks before fruit colour change. Male and female lure baited traps were used to monitor the B. zonata population. Trap catches data were collected every week. 20 random trees were selected for fruit damage data. Infested and healthy fruit data were collected before harvest in treatment area. The farmers’ usual fruit fly treatment practice was considered as control to compare the treatment data.
To evaluate Zonatrac systems longevity, field trial was conducted at Sidi EL Masri, Libya. Trial indicated the consistent effectiveness of Zonatrac up to 12 weeks. The highest average trap catches recorded during the first two weeks was 123-130 peach fruit flies per trap per day (FTD). The average trap catches per trap per day gradually reduced over time and the lowest was recorded during week 12 as FTD 12.44 (See Figure 3).
Figure 3 Average fly catches of male B. zonata per trap per day
TRAP CATCH DATA
Male and female trap catches were collected from two treatment mango plots and control plot. As shown in Figure 4, the Control Plot had the highest number of male B. zonata catches throughout the trial. Treatment Plots A and B had significantly lower trap capture rates up to end of trial. At In 13 weeks, control plot had a significant increase of 968 male flies (73.67% of total B. zonata catches), while the total trap catches for Plots A and B were remain 177 and 169 flies (13.47% and 12.86% of total catches), respectively.
Figure 4. Weekly trap catches recorded in male lure baited McPhail monitoring traps, evenly distributed throughout the mango treatment and control plots.
FRUIT DAMAGE DATA
Fruit samples were collected four times in four different weeks from trial and control plots. Out of 60 mangoes collected from Plot A, only three fruits were found to be infested. The same number of samples collected from Plot B had two fruit infestations. While Plots A and B had zero fallen fruits, the orchard ground in the Control Plot had a significant number of fallen fruits. The Control Plot showed the highest level of fruit damage in comparison to the treatment plots see Figure 5.
Figure 5. Percentage of heathy and infested mango production in treatment and control plots.
This study proved the effectiveness of Ceranock and Zonatrac’s attract and kill strategy to combat fruit flies in both large and small scale orchards of one hectare. This biorational strategy can be used as an alternative to conventional pesticide applications which are becoming increasingly ineffective due to pesticide resistance in B. zonata flies.
The synchronized application of Zonatrac male and Ceranock female attract and kill in mango treatment plots proved to be successful in substantially reducing the populations of B. zonata, which eventually led to minimal fruit infestation. Besides their eco-friendly characteristics, the advantages of the two techniques, include a relatively long lifetime in the field – up to 4 months resulting in significant reduction in labour and maintenance costs.
Ceranock for the control of various fruit flies of economic. Russell IPM has developed innovative attractant and kill systems, Ceranock for the control of various fruit flies of economic importance.
Attract and kill technique uses attractant and insecticides to control fruit fly, by luring and subsequently killing them. The target insect come in contact with the source of attraction and get killed or incapacitated upon contact.
Ceranock system consists on a powerful female food attractant mixed with the toxicant alphacypermethrin. It is remain active over a period of four months. The entire fruit season can be covered by one application of Ceranock system. It is recommended to be used 8 weeks before fruit colour change.
Ceranock system has a range of advantages over other available control systems. In fact, Ceranock is an IPM compatible management tool that ensures zero pesticide application directly onto fruit crops without contaminating the environment. It reduces the amount of pesticide application substantially. It allows fruits free from pesticides residues. Therefore, Ceranock bait station can be a real alternative to organophosphate conventional pesticide application.
In further trials, the Ceranock Attract and kill system was placed in peach orchards in 2 plots named A and B. To evaluate the efficacy of the system in the control of Mediterranean fruit fly, male and female monitoring traps were placed outside the orchard, along the perimeter of the border and in the centre area of each experimental plot. Traps catch data was collected weekly.
Photos courtesy of (L-R) Daniel Feliciano and Imrich,
A significant difference has been observed among the number of captures between the outside, the border and the centre areas for both plots A and B. It is found that the pressure of Med-fly outside the orchard was higher and this is due to the normal presence of the insect in uncontrolled areas outside of the orchard. However, traps near the border trapped 80% and 90% of the total of trapped insect, respectively for plot A and B. In the centre, the number of trap catches was negligible. The Ceranock system was effective in the control of Med-fly by reducing the insect pressure from the border to the center area.
Monitoring traps catches data
Trap catch data of traps baited with Trimedlure was collected weekly in Ceranock plot A and B which were then compared to the control. The results have shown a significant difference in the number of trap catches between treatment and control fields. In fact, for the plot A, a maximum of 226 flies/ trap/ week has been recorded, however in control field captures were doubled, 440 flies/trap/week. Alike for plot B where we noted a maximum of 110 flies/trap/week, beside 268 flies/trap/week in control plot.
Fruit damages assessment
Fruit damages were assessed in treatment area of plot A, B and for control. The number of dropped fruit was counted, then softened fruits were selected and in the laboratory the number of larvae/infested fruit was recorded. To evaluate the total losses, the number of softened fruits that remained on the tree has been also counted.
The results demonstrated a significant difference between Ceranock treated plots and the untreated control. Ceranock treatment proved to be highly effective in the reduction of Med-fly damages in both peach varieties by restricting damage levels up to 5- 6%. Whereas the damage observed in the untreated control plot was up to 56% of fruits.
Recharge- controlling fruit fly from the ground up
Due to the rapid reproductive rate observed in Fruit Fly populations, greater control is often observed when Integrated Pest Management programmes are implemented. Ceranock and Zonatrac will target the adult population to reduce the opportunity for mating and reduce population numbers. Employing larvae control will add an additional layer of control to ensure full protection.
For the larval control of fruit fly, Russell IPM has developed Recharge – a microbe-based soil treatment. Recharge contains natural beneficial microfauna to improve soil health and the immune system of the plant against fruit flies. When applied to soil, the microbial formulation will encounter the overwintering pupae of the fruit fly. After contact, the microbes will prevent the development of the pupae into adult fruit flies as the beneficial microorganisms found in the treatment work to suppress fruit fly pupation which takes place in soil.
Protecting fruit with the attract and kill technique in conjunction with the soil application could potentially result in an income increase for struggling farmers, opening the door for export of the locally grown fruits of Asia and East Africa, into the lucrative European market. A 10% penetration of this market could result in estimated profits of more than US$8m.
Monitoring of the fruit fly population is extremely important for all control systems.
Early detection of a rise in the pest population can be the first indication of a problem and allow for a rapid and effective response to prevent an infestation becoming problematic.
The Flycatcher/McPhail trap is a specially designed monitoring system for multiple fruit fly species. The trap is made of a durable translucent top and bright yellow base with a green cage attached to the upper part. It is reusable and can be used for several seasons. The trap is most suited for use in the trapping of fruit flies in dusty areas. Solid and liquid lures can be used in association with Flycatcher.
The peach fruit fly Bactrocera zonata is an important fruit fly species which mainly attacks mango, guava, peach, apricot, fig and citrus. It is a serious insect pest of mangoes in the Middle East, Near East, North Africa, and to a lesser extent Southern Europe.
Peach fruit flies attack ripe fruits and inflict damage by oviposition and feeding. The oviposition hole provides an entry point for fungal and bacterial infections which eventually cause rot. The peach fruit fly is a serious quarantine pest which can cause up to 100% crop loss when left untreated.
The Mediterranean fruit fly Ceratitis capitata attacks citrus fruits, stone fruits and more than 260 different vegetables, fruit, citrus, pome fruits, stone fruits, berries and nuts. This fruit fly species originated in the Mediterranean and in countries such as Jordan and Lebanon. The pest is currently distributed across Central and South America, Europe and Northern Asia, the Mediterranean Basin and Africa.
Larval feeding in fruit is the most damaging to crops. The larval tunnels provide entry points for bacteria and fungi that cause secondary infections and result in fruit rot.
Ceratitis capitata is highly polyphagous and causes damage to a very wide range of unrelated fruit crops. In Mediterranean countries it is particularly damaging to citrus and peaches. Ceratitis capitata often transmits fruit-rotting fungi. Adults puncture the protective skin of fruits to lay eggs, allowing fungi to infest the crop.
The melon fly, Bactrocera cucurbitae is a fruit fly of cucurbit crops such as cucumber, bitter gourd and courgette. The melon fly is native to tropical Asia and has spread to Pakistan, Papua New Guinea, Guam, Kenya, Tanzania and the Mauritius. Hosts of Bactrocera cucurbitae are mostly from the Cucurbitaceae family such as cucumber, melon and squash. It is also a pest on other plant types such as beans, papaya and ornamental plants.
Females prefer to lay the eggs in soft tender fruit tissues by piercing them with the ovipositor. Larvae feed inside the fruits, flowers, and stems. Punctures by fruit flies have been observed on the fruit skin. Young larvae create a necrotic region where they introduce various pathogens which hasten fruit decomposition.