taxonID	type	description	language	source
03B287CC2000FF96FF4CF9E1FB71F9C2.taxon	description	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. 1 d). 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 M 165 C). 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.	en	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: 227-236, DOI: 10.37828/em.2024.71.23, URL: http://dx.doi.org/10.37828/em.2024.71.23
03B287CC2005FF9DFF4CF95CFA85F8D9.taxon	description	Newly hatched larvae of A. larminati only eat the leaf surface, later they consume the entire leaf. They are usually found on surfaces of leaves and in the upper canopy. The larvae hide within their protective cases by weaving silk and incorporating bits of the host plant's materials (Fig. 3 c). A. larminati larvae extend their bodies out of the protective cases to feed on host foliage. The larvae move the bags to new feeding sites at night. Larvae pull the host materials into the case and consume it while remaining largely hidden from view. Prior to pupation, mature larvae attach their bodies with silk to petioles or leaf margins. This results in a camouflaged structure that blends in with the surroundings over time (Figs. 1 a, b). When the larval density is high, larvae consume all the tree's foliage (Fig. 1), and then move to adjacent trees. Heavily predated trees show reduced vitality over time. Damage incidence and damage index The damage incidence (P %) of A. larminati in C. mollissima plantations in Dien Bien, Lao Cai, Cao Bang, Bac Kan, Lang Son, Hoa Binh, Thanh Hoa and Kon Tum provinces was 20.2 – 81.6 %. The average damage index (DI) was 0.36 – 2.74 (Table 1). The damage incidence and damage index of this pest in C. boisii and L. bacgiangensis plantations in Lang Son, Bac Giang and Hoa Binh provinces were lower, with P % = 11.8 – 17.5 % and DI = 0.13 – 0.27 (Table 1). The C. mollissima trees in plantations were more severely damaged than C. boisii and L. bacgiangensis trees in all surveyed locations. Furthermore, the C. mollissima trees planted in Dien Bien, Hoa Binh and Thanh Hoa provinces were more severely damaged by this pest (P % = 65.5 – 81.6 %, DI = 2.04 – 2.74) than those in Cao Bang province (P % = 20.2 – 22.4 %, DI = 0.36 – 0.49), where this chestnut naturally occurs.	en	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: 227-236, DOI: 10.37828/em.2024.71.23, URL: http://dx.doi.org/10.37828/em.2024.71.23
03B287CC2005FF9DFF4CF95CFA85F8D9.taxon	discussion	Discussion This is the first report of Acanthoecia larminati Heylaerts, 1904 feeding on and causing damage to Castanea mollissima, Castanopsis boisii and Lithocarpus bacgiangensis in Vietnam. The species was described from specimens collected in Tonkin, Vietnam (Société Entomologique de Belgique 1904). It has the following synonyms: Chalia larminati, Chaliella larminati, Heylaertsia larminati, and Kotochalia larminati (Société Entomologique de France 1929; Sobczyk 2011; Jia and Wu 2023). Acanthoecia larminati has been recorded in China, India, Indonesia, Myanmar and Thailand (Jia and Wu 2023). The host plants for this pest are Theobroma cacao (Paerels 1924); Aleurites spp., Morus spp. and Psidium guajava (Chien 1961); Eucalyptus spp. (Zhenghong 2003) and some mangroves (Li et al. 2012). Note: Means with SEs Previous studies have reported low damage incidence of A. larminati (Chalia larminati) in chestnut trees in China (Wu et al. 2000; Peverieri et al. 2017). However, this pest caused widespread damage in C. mollissima, C. boisii and L. bacgiangensis in Vietnam in 2023. In this study, we observed much diversity in the size of larvae, pupae and adults of A. larminati collected from different host plants in Vietnam, and we found that samples collected from C. mollissima were often larger than from the other two chestnuts. The total estimated plantation area of C. mollissima, C. boisii and L. bacgiangensis have reached thousands of hectares (MARD 2023). In recent year, encouraging reforestation with native tree species, especially those with multiple benefits, is a strategy employed by the Vietnamese government (MARD 2014; Vietnam 2021). Over the years, bagworms have been observed as leaf-feeders that can damage chestnut trees, but historically, the level of damage caused by bagworm infestations has been judged to be insignificant (Hue 2015). However, it is possible that expansion of the chestnut plantation area together and climate change have contributed to the rapid development of A. larminati populations. Outbreaks of insect pests and diseases are a threat to planted forests and are always of concern to forest owners, managers and scientists (Ayres and Lombardero 2000; Bosu et al. 2020; Thu et al. 2021). In this study, we observed that some larvae of A. larminati were naturally parasitized by entomopathogenic bacteria (Fig. 4 a) or fungi (Fig. 4 b). As the use of biological agents in pest management is being encouraged (Lee 2009; Jallouli et al. 2020; Tra et al. 2022; Chi et al. 2023), it is recommended that studies to isolate and identify entomopathogenic bacteria and fungi on A. larminati should be undertaken with the view to obtain potential biocontrol agents for the management of this pest in chestnut plantations. Lastly, we do not know if the pest is causing damage in wild chestnut stands in north Vietnam and propose that monitoring be established in these regions. In recent decades, there has been an increase in the number of pests damaging forests in Vietnam (Thu et a l. 2021; Chi et al. 2022 a; Chi et al. 2022 b; Hinh et al. 2023; Pham et al. 2023). Also, there are many pests known to attack chestnuts outside Vietnam such as the chestnut gall wasp (Payne et al. 1978), and fruit borer Dichocrocis punctiferalis (Lee 2009). Hence, there is an ongoing need for active pest surveillance programs in forest plantations in Vietnam. Conclusion Castanea mollissima, Castanopsis boisii and Lithocarpus bacgiangensis trees in plantations in Vietnam are being damaged by the bagworm, Acanthoecia larminati. Damage to C. mollissima plantations is most severe in Dien Bien, Hoa Binh and Thanh Hoa provinces. Control strategies for this pest and screening for resistance are priorities for research in order to safeguard the livelihood of rural communities who depend on chestnuts as a source of food and income. Acknowledgments The authors would like to thank the households and local governments for their support in collecting samples, Dr. John Heppner for his support in identification of the insect pest, and Professor Emeritus Bernard Dell for English language editing. Conflict of interest On behalf of the authors, there are no conflicts of interest.	en	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: 227-236, DOI: 10.37828/em.2024.71.23, URL: http://dx.doi.org/10.37828/em.2024.71.23
