Toxicity of Clove Oil as Influenced by the Size of German Cockroach <i>Blattella germanica</i> L.

Abstract

German cockroaches Blattella germanica L are one of the most common urban pests. Varieties of methods are being used to control this, including spraying, baiting and repellents. Many of these synthetic toxicants cause public health concerns and environmental hazards. There is a need to search for ecofriendly alternatives and clove oil is one such option. There is a need to understand the toxicity of clove oil as influenced by the size of cockroaches, and hence this study was conducted. Cockroaches respond differently to topically applied chemicals on their thorax, wings, and abdomen. Clove oil (16 µl) took significantly longer time to kill smaller-sized cockroaches (004 g). With an increasing topical application of clove oil, the LT50 values decreased. Moreover, cockroaches showed special behaviour such as shrinking abdomen, exhausted gut, or feces, decreased wing thickness, and wing shaking. Thus, this study reveals that clove oil toxicity depends on the body size, and altered the structure of the tissues in cockroaches.