Toxicity of insecticides to the citrus leafminer, Phyllocnistis citrella, and its parasitoids, Chrysocharis pentheus and Sympiesis striatipes (Hymenoptera: Eulophidae)

Abstract

Toxicity of insecticides to the citrus leafminer, AbstractThe experiments were conducted to learn about the relative toxicity of insecticides against the two parasite wasps of citrus leafminer (CLM), Phyllocnistis citrella. The relative toxicity of 12 common insecticides against the eggs and first instar larvae of the pest, and its parasitoids of Chrysocharis pentheus and Sympiesis striatipes, which are dominant species in Ehime Prefecture, was compared in 2003. Corrected mortalities were evaluated by dipping or spraying methods for the CLM eggs and larvae, and by clip-cage bioassay for the parasitoid wasps. All the insecticides tested showed almost over 90% mortality to the first instar larvae of citrus leafminer, but a lesser effect to the eggs. Against the adult parasitoids, imidacloprid (a.i. 0.005%), thiamethoxam (a.i. 0.003%) and acetamiprid (a.i. 0.005%) of the nicotinoide insecticides were less toxic, but dinotefuran (a.i. 0.02%) showed rather high mortalities. Of the IGRs, teflubenzuron (a.i. 0.05%) and diflubenzuron (a.i. 0.012%) were safe or less toxic to adult wasps. These three nicotinoide and two IGRs insecticides will be suitable candidates for use in the IPM program. Isoxathion (a.i. 0.025%) and primiphose-methyl (a.i. 0.056%) of the organophosphate and alanycarb (a.i. 0.04%) of carbamate were highly toxic. Bifenthrin (a.i. 0.0015%) of the pyrethroid and petroleum oil (a.i. 1.05%) were moderate in toxicity. Clothianidin (a.i. 0.005%) of the nicotinoide showed low toxicity to Chrysocharis pentheus but moderate toxicity to Sympiesis striatipes.

Response of citrus peelminer Marmara gulosa Guillén and Davis (Lepidoptera: Gracillariidae) stages to various insecticides

“…In addition, these insecticides are very toxic to Coccinellid predators,16–21 limiting their usefulness in situations where vedalia beetle Rodolia cardinalis (Mulsant) (Coleoptera: Coccinellidae) is needed for control of cottony cushion scale Icerya purchasi Maskell (Hemiptera: Margarodidae). Pyrethroids and neonicotinoids caused more rapid mortality of M. gulosa , but these insecticide classes are toxic to most natural enemies needed for other pests of citrus 15, 20, 22–26. Finally, spinosad and abamectin were quite effective against M. gulosa in this study and are known to be fairly selective, favoring natural enemies 12, 20, 22, 25.…”

Efficacy of Bacillus thuringiensis, mineral oil, insecticidal emulsion and insecticidal gel against Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae)

“…However, the best foliar insecticides keep leaves free of leaf miner infestations for only two weeks (Michaud & Grant 2003). Recently, Mafi and Ohbayashi (2006) found that the percentage corrected mortality of eggs of the citrus leafminer exposed to insecticides (dipping method bioassay) ranged from 3% to 44%, while all tested insecticides gave almost over 90% mortality to the first instar larvae of the citrus leafminer. It is important to select chemicals that are less toxic to the natural enemies to take advantage of both the activity of natural enemies and the control effect of insecticides for suppressing the infestation by CLM.…”

“…Although biological control is the best option for control, an effective control of CLM is very complicated because of its high migration ability from outside of orchards, high fertility, the epidermis of the citrus leaf presents substantial protection, and the difficulty of direct contact of the chemical with the larval body. Furthermore, CLM has a long history of resistance to many insecticides, and development of resistance against a chemical sometimes makes it difficult to obtain sufficiently high control (Mafi & Ohbayashi 2006).…”

Parasitoids Attacking Larvae of a Recently Introduced Weed Biological Control Agent,Neomusotima conspurcatalis(Lepidoptera: Crambidae): Key to Species, Natural History, and Integrative Taxonomy

“…Malaise trap surveys in central Florida detected 9 species of Goniozus (Evans & Fullerton 1997). Species of Sympiesis frequently exploit gracillariid leafminers (Grabenweger & Lethmayer 1999;Mafi & Ohbayashi 2006), including the citrus leafminer P. citrella (Schauff et al 1998), or tortricid leafrollers (Cossentine et al 2004).…”