The population fluctuation of the red palm

Bacillus thuringiensis (Bt) crops are plants genetically engineered (modified) to contain the endospore (or crystal) toxins of the bacterium, Bt to be resistant to certain insect pests. In 1995, the Environmental Protection Agency (EPA) in USA approved the commercial production and distribution of the Bt crops: corn, cotton, potato, and tobacco. Currently, the most common Bt crops are corn and cotton. The crystal, referred to as Cry toxins, is proteins formed during sporulation of some Bt strains and aggregate to form crystals. Such Cry toxins are toxic to specific species of insects belongs to orders: Lepidoptera, Coleoptera, Hymenoptera, Diptera, and Nematoda. In 2016, the total world area cultivated with genetically modified crops (GM crops) reached about 185 million ha. This review shows that there is a worldwide controversy about the safety of Bt crops to the environment and mammals. Some researchers support the cultivation of Bt crops depending upon the results of their laboratory and field studies on the safety of such crops. Others, however, are against Bt crops as they may cause risk to human.

Ten Egyptian and imported entomopathogenic nematodes were evaluated for their pathogenicity to R. ferrugineus in both the laboratory and the field. In the laboratory, most nematodes were pathogenic to the pest larvae, pupae and adults. Larvae and adults were more susceptible to nematode infection (mostly 100 % mortality) than pupae enclosed in their cocoons. In the field however, the highest insect larval mortality was 66.67 % and most of nematodes failed in controlling the pest. Such failure could be due to hot weather, the tunnelling behaviour of the pest larvae and the too much sap in the infested sites in the trunks of palm trees.

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