Compatibility of insecticides and fungicides with the zoophytophagous mirid predator Nesidiocoris tenuis

Abstract

Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) is an effective predator of multiple pests of vegetable crops, such as thrips, mites, aphids, whiteflies, leafminers. It is mass-reared and released for augmentative biocontrol programs mainly aimed at controlling whiteflies and Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) in greenhouses and open field. We evaluated the lethal and sublethal toxicity upon N. tenuis adults of label doses of three insecticides (pyriproxyfen, spirotetramat, cypermethrin) and seven fungicides (benomyl, chlorothalonil, copper oxychloride, cyazofamid, fluopicolide + propamocarb hydrochloride (FPH), penconazol, trifloxystrobin) commonly used in various crops. Two exposure routes were tested: (i) contact with dry residues of insecticides or fungicides on tomato sprouts and (ii) multiple exposure to these chemicals via topical sprays on adults which foraged on treated sprouts; and fed on treated eggs of Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) simultaneously. Mortality and reproductive capacity were investigated as indicators of lethal and sublethal effects on N. tenius. The tested insecticides and fungicides were all classified as harmless when predator was exposed only to the dry residues of each. However, the multiple exposure to either cypermethrin, benomyl, chlorothalonil, copper oxychloride or trifloxystrobin caused significant mortality of N. tenuis adults. Cypermethrin also significantly reduced its reproductive capacity. Interestingly, N. tenuis produced a higher number of progeny when exposed to fungicides penconazol and FPH in both exposure scenarios. Overall, findings suggest that the two insecticides, pyriproxyfen and spirotetramat but not cypermethrin, and all tested fungicides can be considered compatible with N. tenuis.

Compatibility of early natural enemy introductions in commercial pepper and tomato greenhouses with repeated pesticide applications

“…Multiple exposure routes enhance the pesticide risk to NE, as reported by Madbouni et al (2017) for N. tenuis. In our trials, as NE were introduced in the nursery or early in the crop, possible sources of contamination are contact with residues on leaves or with droplets during application, and feeding on contaminated preys or alternative food.…”

“…Therefore, despite the ability of NE to control several pests with simultaneous outbreaks in the crop, chemical treatments are often sometimes needed to maintain key and secondary pest populations under economic thresholds and the ascertaining of their compatibility is crucial for success. Thus, toxicity and sublethal effects of pesticides on NE of horticultural pests has been extensively studied under laboratory or semifield conditions (Amor et al, 2012;Bengochea et al, 2012;Abraham et al, 2013;Döker et al, 2014;Garzón et al, 2015;Maia et al, 2016;Wanumen et al, 2016;De Bortoli et al, 2017;Fernández et al, 2017, Madbouni et al, 2017. In general, much less information is available on the compatibility of novel pesticides and NE inside commercial greenhouses.…”

Selectivity of novel and traditional insecticides used for management of whiteflies on the parasitoid Encarsia formosa

“…The tested insect growth regulator (IGR) pyriproxyfen was harmless to both pupae and adult E. formosa . However, it was harmful for the development of early juvenile stages of E. formosa as was also the case for another aphelinid parasitoid species, Aphytis melinus De Bach, and for the reproduction of the egg parasitoid, Trissolcus japonicus . The effects on immatures were likely due to the inhibition of chitin synthesis and interference with exoskeleton formation after molting …”

“…However, it was harmful for the development of early juvenile stages of E. formosa as was also the case for another aphelinid parasitoid species, Aphytis melinus De Bach, and for the reproduction of the egg parasitoid, Trissolcus japonicus. 29,[49][50][51] The effects on immatures were likely due to the inhibition of chitin synthesis and interference with exoskeleton formation after molting. 52,53 Our results show that dry residues of field-recommended doses of neonicotinoids (imidacloprid, acetamiprid, nitenpyram and thiamethoxam), abamectin, cyantraniliprole and sulfoxaflor were highly toxic to E. formosa adults (causing over 98% mortality).…”

Predation and reproduction of the generalist predator Nabis pseudoferus preying on Tuta absoluta

“…Our study represents a first step toward the integration of N. pseudoferus into a sustainable IPM for T. absoluta in tomato. Further studies are needed to understand its impact on tomato food webs (Jaworski et al, 2015; Naselli et al, 2017), field establishment and dispersal potential after artificial releases (Zappalà et al, 2012; El Arnaouty et al, 2014), compatibility with chemicals (Biondi et al, 2015b; Ziaei Madbouni et al, 2017), and the true pest control ability in the field (Ferracini et al, 2019).…”