Useful information about the distinctive leaf beetle infesting golden apple trees

The Department of Agriculture wishes to inform the general public about the recent identification of a beetle species that poses a threat to golden apple trees Spondias dulcis (frisiter). The beetle, preliminary identified as Podontia quatuordecimpunctata commonly known as leaf beetle, was first observed feeding on golden apple trees in the Bel Air area at the end of 2023, and immediate action was taken to mitigate its impact and prevent further spread.

Identification and Characteristics

Hosts of SLB in the Philippines

Leaf Beetle, Podontia quatuordecimpunctata (L.) is a robust and brightly colored flea beetle, its antenna has 11 segments, the head and pronotum are yellow and the elytra are either salmon pink, orange, or yellow and with yellow legs in the family of chrysomelidae, a defoliator which primarily feed voraciously on the green part of golden apple leaves. The adult is about 5mm in length as outlined in figure 1.

However, after death, the salmon pink elytra turn orange while the yellow elytra turn to cream. There are 14 collective black, irregularly rounded spots on the elytra, thus arriving with the name quatuordecimpunctata or an old abbreviated name of Podontia 14-punctata.

Counting the individual black spots, there are 9–10 on each elytron for a total of 18–20 spots for both males and females. There are five levels of spots: two spots on the anterior, two spots on the apical third, one spot on the medial, two spots on the basal third, and two to three spots on the basal part.

The elytra of a live and healthy beetle are either salmon pink or orange and they turned dark or light orange after death.

The spot in the middle at the basal part is sometimes attached to the spot adjacent to the sutural margin and sometimes individually separated from it. There are also ten distinct longitudinal punctured striae on each elytron. The male has a U-shaped genital opening at the last abdominal ventrite (Figure 1c), whereas the female has none (Figure 1D). Also, the III and IV abdominal ventrites are C-shaped on males and nearly straight on females.

The female lays white clusters of eggs which are elongate-ovate in shape, wider in the middle, round on both ends, and measure about 1.82 × 0.85 mm. The larva is plump, wrinkled and golden yellow with four larva instar stage. The larval head and pronotum are heavily sclerotized, blackish, heart-shaped, and with an inverted “Y”-shaped ecdycial line at the head’s middle portion. The larva range from 8mm to 20mm depending on instar stage. The larva typically covers its body with its feces to serve as a defense mechanism against vertebrate and invertebrate predators (Figures 2(i)B). Additionally, this fecal coat acts as a deterrent against predatory ants. The larva pupates in the soil, thus creating a pupal case out of regurgitated soil particles and mud (Figure 2 (i)C). The adults were occasionally observed mating for long hours and falling to the ground when alarmed (Figure 2(i)D).

Location:

The initial detection of Podontia quatuordecimpunctata was reported in the Belair area on 13^th November 2023. However, the Department of Agriculture is actively monitoring and surveying surrounding regions to assess the extent of its spread.

Preventive Measures Taken: In response to the identification of this beetle, the Department of Agriculture has implemented the following measures:

• Conducted immediate surveys to identify the affected areas which ultimately led to rapid fumigation exercise on all affected golden apple trees in the area.
• Established an Incident Response Team to coordinate and implement control and eradication strategies through fumigation of the affected golden apple trees.

Contact Information:

Please contact the Plant Health Section within the Department of Agriculture at Anse Boileau Research Station on phone number 4355016/ +248 2822912 or the following e-mail address; rgovinden@gov.sc , vhenri@gov.sc .

Community Cooperation:

The Department of Agriculture seeks the cooperation of the public in reporting and preventing the further spread of this beetle. Your vigilance and prompt reporting are essential in preserving our agricultural landscape.

Identification: 

The following photos illustrate the adult leaf beetle and larvae (grub) for easy identification by the public.

The Department of Agriculture remains committed to safeguarding our agricultural resources and appreciates the collaboration of the public in addressing this critical matter.

Measures that can be undertaken by members of the public to manage the pest

1. Cultural Methods:

• Consider cultural methods such as burning to create smoke around the affected trees. Smoke can act as a deterrent to the leaf beetles. Exercise caution when using fire and ensure compliance with local regulations to prevent unintended consequences.

2. Physical Removal (if possible):

• Actively inspect the golden apple trees for adult beetles, larvae, and egg clusters. Physically remove and destroy any beetles, larvae, or eggs found.
• Prune and destroy heavily infested branches by burning to reduce the overall pest population.

3. Use of Household Insecticidal Sprays:

• For manageable-sized trees or individual plants, common household insecticidal sprays can be utilized to control the leaf beetle population.
• Products like DOOM or other suitable insecticides can be sprayed on the foliage following the manufacturer’s instructions.

Human Health and Safety Assurance:

It is important to note that the leaf beetle poses no direct threat to human health. The beetle is primarily a pest that affects the foliage of specific plant species and does not exhibit harmful behavior towards humans. The Department of Agriculture assures the public that:

1. No Human Health Concerns:

• The leaf beetle’s feeding habits are focused on golden apple trees (Spondias dulcis) and do not involve interactions with humans.
• There is no evidence to suggest that the beetle poses any direct health risks or adverse effects on human well-being.

2. No Transmission of Diseases:

• The leaf beetle is not known to transmit any diseases to humans.

Members of the public are encouraged to take necessary precautions when implementing pest management measures, ensuring personal safety and adherence to product guidelines. The Department of Agriculture appreciates the collaboration of the community in addressing this pest issue and assures residents that their well-being is not directly affected by the presence of the leaf beetle.