- The leaf beetles, Altica quercetorum and Agelastica alni are serious pests of urban trees including Quercus sp and Alnus sp, respectively.
- The elm leaf beetle Xanthogaleruka luteola is a serious pest that causes defoliation of eml trees (Ulmus spp.) in North America.
- Adults of these beetles generally feed on leaves by chewing holes through the leaf tissue.
- Larvae skelotonize leaves by feeding on leaf tissues leaving veins and upper epidermis intact.
- Entomopathogenice nematodes including Heterorhabditis megidis, Steinernema carpocapsae and S. feltiae can be used as potential biocontrol agents against different species leaf beetles (read Grewal et al., 2005 for more information).
- It has been shown that both the pre-pupal and pupal stages of A. quercetorum and A. alni are very susceptible to H. megidis when applied in the soil.
- The last instar larvae of X. luteola are highle susceptible to S. carpocapsae when applied to the mulch.
How Entomopathogenic Nematodes kill leaf beetles
- When the infective juveniles are applied to the soil surface or mulch, they start searching for their hosts, in this case leaf beetles grubs.
- Once a beetle grub has been located, the nematode infective juveniles penetrate into the grub body cavity via natural openings such as mouth, anus and spiracles.
- Infective juveniles of Heterorhabditis also enter through the intersegmental members of the grub cuticle.
- Once in the body cavity, infective juveniles release symbiotic bacteria (Xenorhabdus spp. for Steinernematidae and Photorhabdus spp. for Heterorhabditidae) from their gut in grub blood.
- In the blood, multiplying nematode-bacterium complex causes septicemia and kills grubs usually within 48 h after infection.
- Nematodes feed on multiplying bacteria, mature into adults, reproduce and then emerge as infective juveniles from the cadaver to seek new larvae in the soil.
References: Refer following book to read more about efficacy of entomopathogenic nematodes against leaf beetles
1. Grewal, P.S. Ehlers, R.-U., Shapiro-Ilan, D. (eds.). Nematodes As Biocontrol Agents. CAB publishing, CAB International, Oxon