A Laboratory Study of the Cigarette Beetle,Lasioderma serricorne(F.) (Col., Anobiidae) with a critical Review of the Literature on its Biology

Abstract

The paper includes a review of the published literature on the biology of the Cigarette Beetle,Lasioderma serricorne(F.). A list is given of foods on which this species has been found breeding. Information on the duration of the various developmental stages is tabulated and the data on oviposition are summarised. Observations are collected together on the rate of increase of the species in warehouses, on the number of generations per year, on sex ratio, on the use of traps to catch adults and on the spread of the pest and the damage that it causes. The lengths of exposure to various high and low temperatures that are required to give a complete kill of the species are tabulated, and the known natural enemies are listed.Original work includes a morphological comparison ofL. serricorneand the closely related common storage speciesStegobium paniceum(L.). The experimental work consists of a study of the life-cycle ofL. serricorneon wheatfeed over a wide range of combinations of constant temperature and humidity. Development was possible from just under 20°C. to 37·5°C. at favourable humidities. Larvae died at 90 per cent. R.H. at 37·5°C. The lower humidity level for development was under 25 per cent. R.H. at 30°C. but change of temperature, both up and down, raised the lower humidity limit so that, at 20°C. and 37·5°C., all larvae died at 40 per cent. R.H. When fed on foodstuffs such as groundnuts, which contain less water than wheatfeed at all humidities, the effects of low humidity are more rigorous. The effect of a number of foodstuffs on the length of the developmental cycle was investigated. The duration of larval instars on wheatfeed at 30°C. and 70 per cent. R.H. was found. The adults obtained in the experiments were weighed. The heaviest insects were obtained at 25°C. and 100 per cent. R.H. Higher temperatures and low humidities reduced weight. Females were heavier than males. The sex ratio was unity.The oviposition rate was investigated at 70 per cent. R.H. over a wide temperature range. Under all conditions the eggs were laid quickly. At this relative humidity, no fertile eggs were laid at 37·5°C. and few pairs laid at 20°C. The total number of eggs laid per female at 20°C. was low, otherwise temperature had little effect on the number of eggs laid, but the rate of oviposition was increased by high temperature. The theoretical rate of increase at 70 per cent. R.H. was calculated for several temperatures and shown to increase with temperature up to 35°C.The conclusions on the distribution and multiplication of the species which can be drawn from the laboratory results are discussed.