ABSTRACT

Predatory ants are crucial biological control agents in agroecosystems, but such activity may vary during dry and wet seasons. In this study, we investigated whether the mortality caused by predatory ants to the larvae of Ascia monuste orseis (Godart) varies due to the effects of dry and wet seasons. We performed a field experiment repeated eight times for two years. In each period, we established a cabbage plot containing 40 plants and inserted another ten plants containing 45 ± 13 (mean ± standard deviation) larvae to estimate the mortality rates. We monitored ant predation by direct observations performed twice a day (08:00–10:00 and 15:00–17:00). During the experiment, the average daily temperature varied significantly (from 13°C to 27°C) with higher values during wet seasons, while for precipitation and relative humidity, we found significant variation only in the second year. Despite this, the mortality caused by ants did not vary between seasons in the same year. Mortalities (mean) were estimated at 13.81% (dry season, year 1), 10.45% (wet season, year 1), 23.47% (dry season, year 2), and 23.29% (wet season, year 2). Ants were found to belong to the genus Ectatomma, Camponotus, Pheidole, Pseudomyrmex, Solenopsis, and Tetramorium. Thus, our study indicates that predatory ants may be present year-round on Brassica crops, contributing to the biological control of A. monuste orseis.

摘要

捕食性蚂蚁是农业生态系统中至关重要的生物控制剂，但这种活动在旱季和雨季可能会有所不同。在这项研究中，我们调查了捕食性蚂蚁对Ascia monuste orseis幼虫的死亡率是否(Godart) 因旱季和雨季的影响而变化。我们进行了一项为期两年、重复八次的田间试验。在每个时期，我们建立了一个包含 40 株植物的白菜地块，并插入了另外 10 株含有 45 ± 13（平均值 ± 标准差）幼虫的植物来估计死亡率。我们通过每天两次（08:00–10:00 和 15:00–17:00）的直接观察来监测蚂蚁的捕食情况。试验期间，日平均气温变化显着（从 13°C 到 27°C），雨季值较高，而对于降水和相对湿度，我们只在第二年发现了显着变化。尽管如此，蚂蚁造成的死亡率在同一年的季节之间并没有变化。死亡率（平均）估计为 13.81%（旱季，第 1 年）、10.45%（雨季，第 1 年）、23.47%（旱季，2 年）和 23.29%（雨季，第 2 年）。发现蚂蚁属于该属Ectatomma、Camponotus、Pheidole、Pseudomyrmex、Solenopsis和Tetramorium。因此，我们的研究表明，掠食性蚂蚁可能全年存在于芸苔属作物上，有助于对A. monuste orseis 进行生物防治。