Distribution and damage potential of pulse beetles, Callosobruchus spp. (Coleoptera: Bruchidae) in Sindh, Pakistan

Callosobruchus spp. are global serious pests of pulses. Therefore, two studies were carried out to determine their distribution in three ecological zones of the Sindh, Pakistan along with their damage potential to major pulses. Survey was conducted from Zone-one (Ghotki, Sukkur and Larkana districts), Zone-two (Hyderabad, Mirpur Khas and Shaheed Benazirabad districts) and Zone-three (Karachi district) during March – April 2020. Grain samples of main pulses i.e., chickpea (channa), field pea (matar), cowpea (lobia), green lentil (moong) and daal channa were collected from three locations of each district and brought to Stored Grain Research Laboratory, Department of Entomology, Faculty of Crop Protection, Sindh Agriculture University, Tandojam for further examination. Three pulse beetle species i.e., C. maculatus, C. chinensis and C. analis were identified from the collected pulse samples as the highest populations of adults, eggs, grubs and pupae was recorded from moong, followed by lobia and gram. No population of pulse beetle was recorded from daal channa and matar. Callosobruchus maculatus was the most dominant species at all sampling as higher beetle populations were recorded from Mirpur Khas and Sukkur districts. Therefore, both these strains were further evaluated for their feeding preference and weight loss assessment on various pulses i.e., gram (chickpea), lobia (cowpea), moong (green gram) and daal channa (yellow lentil) in no-choice under laboratory conditions. C. maculatus showed a significant feeding preference among pulses with lobia and gram being the most preferred, whereas daal channa was the least preferred, hence suffered highest and lowest weight loss, respectively. Therefore, proper storage and quarantine measures are suggested to be taken in the transportation and storage of pulses to restrict the spread and damage of pulse beetles.