Tree growth losses from Gonipterus sp. 2 feeding damage on Eucalyptus plantations and quantified economic impact

Economic impact and re-establishment of biological control for Gonipterus sp. 2 in Eucalyptus plantations in South Africa data including figures, r codes, and datasets. Gonipterus sp. n. 2 (Coleoptera: Curculionidae), native to Australia, was reported in South Africa in 1916 and has become a serious pest in Eucalyptus plantations. The adults and larvae feed on young and tender leaves of Eucalyptus which can result in a reduction in tree growth and/or extension of rotation length and thus negatively affect economic benefits derived from plantations. Despite the economic importance of Eucalyptus and the threat posed by Gonipterus sp. n. 2, there is a lack of knowledge on the economic impact of this insect in South Africa. The main control strategy for Gonipterus sp. n. 2 is biological control, using a solitary egg parasitoid wasp, Anaphes nitens Girault (Hymenoptera: Mymarid). However, there are still outbreaks of Gonipterus sp. n. 2 despite the presence of this biological control agent, thus necessitating the use of alternative control measures for effective integrated pest management. In this study, the tree growth losses and corresponding economic impact of Gonipterus sp. n. 2 were quantified from insect exclusion trials, and the effect of cypermethrin (pyrethroid insecticide) on the re-establishment of A. nitens was also investigated. The insect exclusion trials consisted of chemically treated plots for the exclusion of Gonipterus sp. n. 2 and untreated plots for this beetle to freely feed. Results from insect exclusion trials showed that Gonipterus sp. n. 2 can result in a significant 17.5% (p = 0.022) reduction in wood volume from cumulative 18% defoliation of two assessment events which translates to a projected economic impact of between R6 399.22/ha (344.11 USD) and R29 224.53/ha (1571.51 USD) at harvest (8 years). The effect of cypermethrin on the re-establishment of A. nitens was investigated by comparing parasitism rates from chemically treated and untreated treatments, before and after spraying of  ~2-year-old (at time of last egg collection) Eucalytpus dunnii. Gonipterus sp. n. 2 egg capsules were collected from the field for assessment of parasitism rates. It was found that the insecticide did not influence the parasitism rate (re-establishment) of the parasitoid, indicating potential compatibility between biological and chemical control of Gonipterus sp. n. 2, although larger trials are needed to confirm the results. This is the first study in South Africa to quantify the economic impact of Gonipterus sp. n. 2 and the compatibility of cypermethrin (one of the most used broad-spectrum insecticides) with A. nitens in the field.

该数据集包含南非桉树种植园中Gonipterus sp. 2的经济影响及生物控制重建的相关数据，包括图表、R代码和数据集。Gonipterus sp. n. 2（鞘翅目：象甲科），原产于澳大利亚，于1916年首次报道出现在南非，已成为桉树种植园的一种严重害虫。成虫和幼虫以桉树嫩叶为食，可能导致树木生长减缓及/或轮作周期延长，从而对种植园的经济效益产生负面影响。尽管桉树的经济价值巨大，Gonipterus sp. n. 2带来的威胁亦不容忽视，但目前关于该昆虫在南非的经济影响仍缺乏认识。Gonipterus sp. n. 2的主要控制策略为生物控制，采用单寄生蜂Anaphes nitens Girault（膜翅目：细腰茧蜂科）。然而，尽管存在此生物控制因子，Gonipterus sp. n. 2仍时有爆发，因此需要采用替代控制措施以实现有效的综合害虫管理。在本研究中，通过对昆虫隔离试验进行量化，评估了Gonipterus sp. n. 2造成的树木生长损失及其相应的经济影响，并研究了拟除虫菊酯（一类广泛使用的拟除虫菊酯类杀虫剂）对A. nitens重建的影响。昆虫隔离试验包括对Gonipterus sp. n. 2进行化学处理的隔离地块以及未处理的自由取食地块。昆虫隔离试验的结果显示，Gonipterus sp. n. 2可能导致累积18%落叶后木材体积显著降低17.5%（p = 0.022），在收获时（8年后）预计的经济影响介于每公顷R6 399.22（344.11美元）至R29 224.53（1571.51美元）。通过比较化学处理和未处理处理方式的寄生率，在喷洒约2年生的桉树（最后一次收集卵的时间）之前和之后，研究了拟除虫菊酯对A. nitens重建的影响。从田间收集Gonipterus sp. n. 2的卵囊以评估寄生率。研究发现，杀虫剂并未影响寄生蜂的寄生率（重建），表明生物控制和化学控制Gonipterus sp. n. 2之间可能存在兼容性，尽管需要更大规模的试验来验证结果。这是南非首次量化Gonipterus sp. n. 2的经济影响，以及拟除虫菊酯（最广泛使用的广谱杀虫剂之一）与A. nitens在田间兼容性的研究。