Pesticide-Resistant Insects Create Problems for Dry Bulk Terminals

Dry bulk terminal operators warn that the fumigation of grain cargoes using common insecticides may not be effective in controlling insect larvae, resulting in cargo damage and costly grain silo infestations. 

“We are finding that the pupae and larvae inside maize kernels in various consignments, and which were subjected to in-transit fumigation, are not affected by phosphine or phosphine generating fumigants and growing into weevils while cargoes are in storage,” said Javier Quintero Saavedra, head of HSE at Spanish terminal operator Terminales Marítimos de Galicia (TMGA) and chairman of the Dry Bulk Cargoes Working Group at ICHCA.

Resistance to phosphine has been documented in rice weevils in Vietnam and China and grain borers in North America, Brazil and Australia, and the pests' ability to withstand this industry-standard fumigant is a growing problem for agribusiness. Weevils remaining in the port warehouse are a real issue for terminal operators, particularly if the operator has only been accustomed to handling grain, meal or feedstocks that are not prone to infestations.

Saavedra, who will present a case study relating to the pest control challenges facing terminal operators at the Association of Bulk Terminal Operator’s (ABTO) annual conference this October, explained that while consignees had arranged for cargo fumigation both in transit and during storage upon discharge, insects plagued his company's silos, requiring extensive cleaning, space treatment with contact insecticide, and restoration of silo walls.

“Bulk terminals need to implement a fully integrated pest management plan. Operators must monitor silo temperatures and moisture and be able to spot insect and larvae infestations in large storage premises. They should also carry out regular cleaning of empty stores and better understand the use of different pesticides and their effects," advises Saavedra. 

“While grain cargoes are usually fumigated at origin or in-transit, if larvae survive and evolve it can be a real issue for terminal operators. It can write-off the whole consignment," said ABTO CE Simon Gutteridge. "There is obviously a strong case for fumigating cargoes stored in silos at discharge ports, especially where maize kernels are stored, but this is not without its own problems.”

The standard fumigant is phosphine or a phosphine generating product, which is a well-documented health and safety risk in the seaborne transportation of grain. Exposure to this gas has resulted in acute intoxication, hypoxia, asphyxiation and seafarer fatalities. The risk in shore storage premises is that the fumigant can leak to adjacent areas.

Methyl bromide, another pesticide widely used in the containerised transportation of grain, has also been attributed to intoxication-induced fatalities. It is also banned in a number of countries as it is a known ozone-depleting substance.

“There are IMO guidelines for the use of pesticides in transit, but the rules governing their use in storage facilities ashore is at national level. Although the European Commission oversees the approval of active substances, it is the individual state that decides whether to allow their use or not,” said Saavedra. “What the bulk terminals industry needs is more globally-focussed best practice guidelines, an initiative supported both by ICHCA and ABTO.”