Acanthoecia, de Joannis, 1929

Chi, Nguyen Minh, Loi, Vu Van, Thuy, Pham Thi Thu, Anh, Chung Nhu, Phuong, Tran Thi, Bao, Hoang Quoc, Van, Cao Van, Truong, Pham Xuan, Ha, Dinh Thi, Long, Bui Duc, Vuong, Tran Quy & Pham, Duy Long, 2024, A bagworm damaging chestnut trees in Vietnam, Ecologica Montenegrina 71, pp. 227-236 : 228-229

Collection of Acanthoecia from chestnut trees

Specimens of bagworms were collected systematically in October and December 2023 from heavily infested Castanea mollissima plantations in Dien Bien, Lao Cai, Cao Bang, Bac Kan, Lang Son, Hoa Binh, Thanh Hoa, and Kon Tum provinces; and from Castanopsis boisii and Lithocarpus bacgiangensis plantations in Lang Son, Bac Giang and Hoa Binh provinces ( Figs. 1 a-c). To investigate the developmental stages, five individual trees of the three chestnut species heavily defoliated by Acanthoecia bagworm in each province were selected in October 2023, and then a net cage (40 × 60 × 40 cm) was used to enclose the host branches with caterpillars inside their protective bags ( Fig. 1d ). The rearing period of Acanthoecia , including egg, larval, pupal and adult stages, lasted from October 2023 to January 2024.

The study sites have a tropical monsoon climate with four distinct seasons, an altitudinal range of 400–1,000 m, terrain with a slope of 15–20%, and annual rainfall and temperature of 1,500 –2,800 mm and 18–23 °C, respectively. The C. mollissima , C. boisii and L. bacgiangensis plantations were 3– 20 ha in size with a density of 500–830 trees/ha, with no fixed spacing between trees (scattered plantings).

Characterization and identification

Larval, pupal and adult morphology were described from specimens reared in the field inside the netted bags. Eggs were removed from the bags of field-collected females which were still alive. Under laboratory conditions, females were separated one day after mating and examined for the presence of eggs. All measurements were made using a compound microscope (Leica M165C). Gross measurements were made with a standard millimetre ruler. The wing expanse was measured from the extreme apex of one wing to that of the other. The length and breadth of larvae were measured across the widest point of the pronotum.

Species identification was based on the external morphology of 40 adult specimens (20 males, 20 females) using the keys in Société Entomologique de Belgique (1904) and Sobczyk (2011), and these specimens were deposited in the insect collection of the FPRC in Hanoi, Vietnam .

Figures

Figure 1. Symptoms of Acanthoecia larminati attack in chestnut trees: a. Castanopsis boisii tree; b, c, d. Castanea mollissima trees; a. damaged tree in Luc Nam, Bac Giang with larval chambers on the branch; b. damaged tree in Kon Plong, Kon Tum with larval chambers on the branch; c. damaged trees in Trung Khanh, Cao Bang; d. damaged trees in Tan Lac, Hoa Binh with a net cage used for rearing this pest.