Helicoverpa zea attacks soybean crop INTACTA 2 XTEND

Since the approval of Bt (transgenic) technology in Brazil in 2007, caterpillar management has reached a new technological level. In transgenic soybean cultivars, approved in 2010, the technology provided more protection for the plants in relation to damage caused by the caterpillar complex.

The latest soybean launch on the market, called INTACTA 2 XTEND, features three proteins (Bt): Cry1A.105, Cry2Ab2 and Cry1Ac. In these varieties, the proteins work simultaneously to offer more comprehensive protection. Its target now includes two species of great importance: Helicoverpa armigera e cosmioides spodoptera. And they maintain their action against soybean caterpillars (Anticarsia gemmatalis), false-measurement (Chrysodeixis includens), armpit borer (Crocidosema aporema) and apple caterpillar (Chloridea virescens). To date, no escapes from caterpillars listed in their protection guarantee have been reported in soybean crops.

However, in the current harvest (2022/23), in the city of Acreúna (GO), one fact caught attention: the crop with INTACTA 2 XTEND soybeans presented outbreaks of small and large caterpillars feeding on the crop, with characteristics of Helicoverpa ssp.

Specimens of this population were collected on 10/11/2022, in the larval stage, and kept in the MRE Agropesquisa laboratory. The following day, 30 caterpillars were placed in falcon tubes, containing 96% alcohol, and sent to a qualified laboratory to carry out identification through molecular analysis. The result was surprising: all the caterpillars were identified as Helicoverpa zea (corn earworm). The typical corn caterpillar now breaks barriers and starts causing damage to soybeans.

It is possible that caterpillar escapes are occurring in other producing regions throughout Brazil. Soybean cultivars available on the market with technology (Bt) guarantee protection against Helicoverpa armigera. None provide protection for Helicoverpa zea. Therefore, there may be a predominance of Helicoverpa zea in soybean crops.

As control tactics to be recommended, the same tools used in controlling the Helicoverpa armigera in soybeans.

This first identification of the occurrence of Helicoverpa zea in soy which has three proteins (Bt) raises the alarm for intensified sampling in soybean crops. And also to recover the engagement of rural producers in relation to tactics that aim to delay the evolution of insect resistance.

By Estevão Rodrigues, Raphael Neumeister, MRE Agropesquisa; Evania Alves, Agricultural Engineer; Márcio F. Peixoto, Biotech and Peixoto Agropesquisa -- Article published in Issue 284 of Cultivar Grandes Culturas magazine