Lethal and Sublethal Effects of Insecticides Used on Citrus, on the Ectoparasitoid Tamarixia radiata

Huanglongbing (HLB) is a disease associated with the bacteria "Candidatus Liberibacter spp." and has been devastating citrus orchards around the world. Its management involves control of the insect vector, the Asian citrus psyllid Diaphorina citri Kuwayama. However, the indiscriminate use of chemicals has caused pest outbreaks and eliminated the natural enemies of the vector, such as the parasitoid Tamarixia radiata (Waterston), the main agent for biological control of D. citri. This study assessed the lethal and sublethal effects of insecticides recommended for integrated production of citrus on the parasitoid T. radiata. When adult parasitoids were exposed to residues of 25 insecticides, 20% of them, i.e., gamma-cyhalothrin, etofenprox, azadirachtin, tebufenozide and pyriproxyfen, were considered as harmless (Class 1), 12% as slightly harmful (Class 2), 12% as moderately harmful (Class 3) and 56% as harmful (Class 4), according to the classification proposed by the IOBC/WPRS. Afterward, 14 insecticides (5 harmless and 9 harmful) were sprayed on the parasitoid pupae. Of the 14 insecticides tested, only the organophosphates dimethoate and chlorpyrifos affected the parasitoid emergence. The effects of insecticides on the parasitism capacity of adults exposed to residues of azadirachtin, etofenprox, gamma-cyhalothrin, pyriproxyfen and tebufenozide (harmless) were also evaluated. Tebufenozide and gamma-cyhalothrin affected the parasitism of the F0 generation, but did not affect the emergence of the F1 and F2 generations. Therefore, for an effective IPM program, selective insecticides or harmful pesticides to adult parasitoids could be used in the field, provided that the adults do not occur naturally and the chemical applications do not coincide with parasitoid releases

Advanced nano-biocomposites based on starch

Starch as a biopolymer directly extracted from nature has received much attention in recent years due to its strong advantages such as low cost, wide availability, renewability, and total compostability without toxic residues. Starch-based materials always display properties that are less satisfactory than those of traditional polymer materials, which can be ascribed to the inherent characteristics of starch. To make such materials to be truly competitive and to widen its applications, the development of starch-based nano-biocomposites could be a promising solution. This chapter provides the fundamental knowledge related to starch-based nano-biocomposites as well as the most recent developments in this area. Various types of nanofillers that have been used with plasticized starch are discussed such as montmorillonite, cellulose nanowhiskers, and starch nanoparticles. The preparation strategies for starch-based nano-biocomposites with these types of nanofillers and the corresponding dispersion state and related properties are also largely discussed