Changes in modern agricultural practice have allowed an increased production of fertilizers, herbicides and other pesticides causing important negative effects on the environment worldwide. Organic fertilizers are also extensively applied to agricultural lands, but they can contain bacteria and a large variety of microbial communities and parasites that can be rather pathogenic for wildlife. Also, because trace elements are often added to poultry diets to increase resistance to diseases of farm animals, poultry litter can also contain trace elements which are potentially toxic to living systems when present in high concentrations. We have examined experimentally the effect of commonly used mixtures of organic and mineral fertilizers and herbicides on the mortality of insects. Mealworms of Tenebrio molitor (n = 300) were exposed for four weeks to four different treatments: organic liquid fertilizer (pig manure), organic solid fertilizer (turkey litter), mineral fertilizer (nitrates), and herbicides (a mixture of glyphosate and 2, 4-D). After four weeks in direct contact with all treatments, mealworm mortality ranged from 74 percent to 88 percent. Surprisingly, control mealworms placed in the same room with the other treatments also experienced high mortality (72 percent) while mortality of control-isolated mealworms was low (eight percent), suggesting that volatile compounds from tested products can be noxious to insects. Our results also indicate that more individuals escaped from the herbicides and nitrate treatments than from the others, suggesting some kind of behavioural avoidance of toxic environments. The traditional organic fertilizers appear to be less toxic than inorganic fertilizers for the species studied. Organic fertilizers from farms should be adequately treated before being dispersed into the environment. Also, mineral fertilizers and herbicides should be used with moderation and well in the prescribed proportions to reduce their damage to the environment.


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  • Received: 05 March 2012
  • Accepted: 05 March 2012
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