The effects of pesticide residues on natural enemies (Mallada basalis and Eocanthecona furcellata) in strawberry pest management
Date Issued
2016
Date
2016
Author(s)
Wang, Hao-Ping
Abstract
The generalist predators Mallada basalis and Eocanthecona furcellata are important natural enemies in agricultural ecosystems in Taiwan. The green lacewing M. basalis is considered as an important natural enemy of several pests of economic importance because of their polyphagous feeding habits. The stink bug, E. furcellata, is a predatory insect that can be commonly found on horticultural plants preying on various lepidopterous insect pests in Taiwan. Releases of these predator are carried out, and it is included in the Integrated Pest Management (IPM) programs of several crops. The accurate assessment of the compatibility of various pesticides with predator activity is the key to the success of this strategy. In order to identify products with low toxicity or short duration effects on biological control agents, we assessed contact toxicity, irritancy and residual toxicity of 15 pesticides on M. basalis larvae and contact toxicity, feeding toxicity and residual toxicity of 15 pesticides on E. furcellata nymphs both under laboratory conditions and semi-field experiments. Pesticides commonly used in either conventional or organic farming in strawberry pest management were selected for the study, including three synthetic fungicides, three synthetic insecticides, one acaricide and eight organic certified pesticides. In semi-field experiments, residues were aged under greenhouse conditions for 0, 1, 2, 3, 5, 7, or 14 d and introducing insects to test residual toxicity. The percentage of mortality was classified according to the IOBC (International Organization for Biological Control) toxicity categories and modified. The results showed that the pesticides greatly differed in their toxicity, in terms of lethal effects, as well as in their persistence. For M. basalis, chlorfluazuron and lamda-cyhalothrin caused high mortality and persistence, and chlorfluazuron was classified as harmful (rating class 2) up to 14 d after the treatment and lamda-cyhalothrin was classified as harmful (rating class 2) up to 2 d after the treatment . In particular, mineral oil was classified as rating class 4, but in semi-field it was low toxic to lacewing larvae. The irritant and repellent effects of low toxic pesticides were also examined on larvae of the lacewings, and there was no statistically significant avoidance between pesticide treatments and water control. It is concluded that these pesticides are not intrinsically irritating or repellent to M. basalis larvae. For E. furcellata, chlorfluazuron caused both high feeding toxicity (rating class 4) and high contact toxicity. In semi-field experiment, chlorfluazuron was low toxic (rating class 2) until 1 d after the treatment, and lamda-cyhalothrin also caused high mortality and persistence, and it was low harmful up to 14 d after the treatment. Imidacloprid consistently caused low toxicity (rating class 2), even after aging for 3 d. Almost all organic certified pesticides and fungicides had low toxicity, and along with the organic certified products and fungicides could be compatible with biological control in strawberry pest management program. This study provides information to guide strawberry growers in their selection of pesticides, and appropriately releasing time of M. basalis larvae and E. furcellata nymphs after pesticides application.
Subjects
Biological control
Strawberry
Mallada basalis
Eocanthecona furcellata
Type
thesis
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