Allocation of more reproductive resource to egg size rather than clutch size of gregarious desert locust (Schistocerca gregaria) through increasing oogenesis period and oosorption rate

•Crowded desert locusts produce fewer but larger eggs than isolated ones.•Oocyte and ovarian growth rates were almost similar between isolated and crowded conditions.•Crowded females prolonged the oogenesis period and produced larger eggs than isolated females.•Crowded females showed increased oosorption rates and reduced clutch sizes.