Insecticide control of a white grub,Maladera matrida,on sweet potato

In an effort to control the damage caused by the beetleMaladera matrida Argaman (Coleoptera: Scarabaeidae) to sweet potatoes,Ipomoea batatas (L.) Lam., experiments comparing heptachlor with other insecticides were conducted in the Besor region in the southern part of Israel in 1987. Taking the percentage of clean tubers at the final harvest as the criterion of insecticidal efficacy, the best results were achieved with heptachlor (97.3% clean tubers) and with the synthetic pyrethroid Talstar (biphenthrin) (91.1% clean tubers), while the percentage of clean tubers obtained in two untreated control plots was 52.5% and 65.9%. The effect of heptachlor and Talstar was not significantly different from that of Oftanol (isofenphos) plus Becis (decamethrin), but was significantly better than that of Dizictol (diazinon), Becis, Dizictol plus Becis, Oftanol, and the untreated controls. The average tuber weights from the treatments with heptachlor, Talstar and Becis were significantly higher than those of the untreated control plots and from the treatments with Dizictol, Oftanol, and Oftanol plus Becis.