Guava Fruit Fly
Bactrocera correcta
📖 Description
Bactrocera correcta, the Guava Fruit Fly, is one of the most economically damaging tephritid fruit flies in the Indian subcontinent and a quarantine concern in many importing countries. The species is closely related to the Oriental fruit fly (B. dorsalis) and shares many biological features, but B. correcta is more specifically associated with guava in India — the two species coexist in many orchards but B. correcta dominates on guava while B. dorsalis dominates on mango. Female flies use their horny ovipositor to puncture the ripening fruit skin and lay a clutch of 10–30 eggs in the flesh beneath; the emerging maggots feed on the pulp for 7–12 days, causing it to soften and rot, and then drop to the soil to pupate. The entire lifecycle can be completed in as little as 25–30 days during summer, allowing rapid population build-up. India is the world’s largest guava producer (over 4 million tonnes per year), with major orchards in Uttar Pradesh (Allahabad/Prayagraj, Kanpur), Bihar, Andhra Pradesh, Maharashtra, and West Bengal. The rainy-season crop (June–September harvest) is disproportionately affected because the soft rainy-season fruit skin is easy to puncture and the humid conditions favour fly activity — in some orchards 80–100 % of rainy-season fruit is infested. The economic response has been a widespread shift to the winter-season crop (October–February harvest) which commands a price premium and is far less attacked. Methyl-eugenol-based male annihilation technology (MAT) combined with protein-bait sprays and fruit-bagging forms the core of IPM packages developed by IIHR Bangalore and CISH Lucknow.
⚠️ Symptoms to watch for
- Pinhead-sized dark oviposition punctures on the fruit surface — the first diagnostic sign; soft brown sunken patches developing around the punctures; premature fruit yellowing and drop; fruit splitting open to reveal maggots when squeezed. Heavy infestation can cause 60–90 % fruit loss in untreated guava orchards during the rainy-season crop (June–September) in Uttar Pradesh, Bihar, Andhra Pradesh, and Maharashtra. The rainy-season crop is most affected because adult flies are highly active in humid conditions and the soft rainy-season fruit skin is easier to puncture.
🩹 Treatment
- Cultural: collect and destroy all fallen and infested fruits daily by deep burial (60 cm) or burning — this is the single most effective cultural practice. Mechanical: install methyl-eugenol-baited para-pheromone traps at 4–8/ha to mass-trap adult males (B. correcta responds strongly to methyl eugenol) and reduce mating success. Biological: apply Spinosad-based protein-bait sprays at 0.02 % — the bait attracts both sexes and kills on contact. Chemical: bait spray with malathion 50 EC + jaggery (1:1 in 5 L water) sprayed on the lower canopy at 30–50 mL per tree, repeated at 15-day intervals during fruit maturation.
🌿 Organic treatments
- Install methyl-eugenol traps at 8/ha from pre-fruiting onwards (note: methyl eugenol is the most effective lure for B. correcta, and some certification bodies permit its use as a trapping lure); Spinosad-based GF-120 fruit fly bait at 1 L/ha; collection and deep burial of all fallen fruits daily; bagging individual fruits with paper or polyethylene bags soon after set; use of neem oil at 3 % emulsion as a fruit-surface repellent.
🧪 Chemical treatments
- Malathion 50 EC @ 2 ml/L + jaggery 10 g/L as bait spray (lower canopy only), Lambda-cyhalothrin 5 EC @ 0.5 ml/L (full canopy, but high natural enemy impact), Spinosad 45 SC @ 0.5 ml/L + protein hydrolysate at 1 g/L as bait. Pre-harvest interval 7 days for malathion, 3 days for Spinosad.
🛡️ Prevention
- Adopt the winter-season crop (October–February harvest) rather than the rainy-season crop — winter fruit is far less attacked because cool dry conditions suppress fly activity; collect and destroy all fallen fruits daily during the fruiting period; install methyl-eugenol traps at 4–8/ha from pre-flowering; bag individual fruits with paper bags soon after set — most practical for high-value table varieties; remove alternate wild hosts (Tropical almond, wild guava) from orchard margins; harvest fruits at the mature-green stage to minimise field exposure to oviposition.
🪴 Affected plants
- Guava (Psidium guajava) — primary host in India; also infests mango, peach, apricot, citrus, jujube (ber), sapodilla, papaya, and many wild hosts including tropical almond (Terminalia catappa) and Syzygium spp.
🦋 Natural predators
- Opius spp. and Fopius spp. (braconid larval-pupal parasitoids — introduced for classical biological control but with modest field parasitism of 5–15 %), Dirhinus spp. (pupal parasitoid), predatory ants (Solenopsis, Pheidole) that attack pupating larvae in soil, and birds that consume infested fruits and the maggots within.
🌱 Host plants
- Psidium guajava (guava — primary host), Mangifera indica (mango), Prunus persica (peach), Prunus armeniaca (apricot), Citrus spp., Ziziphus mauritiana (ber), Manilkara zapota (sapodilla), Carica papaya (papaya), Terminalia catappa (tropical almond), Syzygium spp.
🔄 Lifecycle
- Adult female lays 100–300 eggs in batches of 10–30 inside the fruit flesh through a puncture made by the ovipositor.
- Egg stage 1–3 days in summer, up to 7 days in winter.
- Larva feeds inside fruit for 7–12 days through three instars.
- Mature larva drops to soil and pupates 5–10 cm below the surface; pupal stage 7–14 days.
- Adult longevity 30–90 days (females live longer than males).
- Total lifecycle 24–35 days in summer, 50–70 days in winter.
- Eight to ten overlapping generations per year in tropical India.
📅 Season
- Active year-round in tropical India; peak infestation during the monsoon and post-monsoon (June–October) when guava is in fruit and humidity is high.
- Winter populations are low but persist on alternate hosts.
🔎 Appearance
- Adult is a medium-sized tephritid fruit fly with a reddish-brown body, predominantly yellow thorax with two lateral and two medial dark stripes, and a conspicuous black T-shaped mark on the abdomen.
- Wings are transparent with a brown costal cell and a small dark spot at the apex.
- The female has a sharp, black, horny ovipositor at the tip of the abdomen.
- Larva is a typical legless white maggot, tapering anteriorly with dark mouth-hooks, and a blunt posterior bearing two posterior spiracles each with three slits — the diagnostic feature for species identification.
💥 Damage level
- Severe
🔁 Reproduction rate
- Fast
🗺️ Geographic regions
- Indian Subcontinent (endemic and widespread)
- South Asia
- Southeast Asia (Thailand
- Vietnam
- Myanmar)
- and increasingly intercepted in quarantine in importing countries.
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