Insect and Rodent Prospects for 1960

Weather conditions during the growing season pretty much determine the size of the insect problem in any given year. Keeping this in mind, here are the prospects for 1960- depending on the weather

Systemic Insecticides Control Cattle Grubs

Systemic grub killers now available are effective in controlling cattle grubs when used as recommended. In tests, better gain on less feed and higher market returns more than offset the cost of treatment

Fight Borers by Land or by Air

Many Iowa farmers used some form of DDT to control the the borer last season. There were some differences in the control measures used and in the results obtained

Population Suppression of Western Corn Rootworm by Adult Control with ULV Malathion

ULV malathion (9.7 oz AI/acre) was applied by air to a 16 square-mile area during August of 1968, 1969, and 1970. Adult Diabrotica virgifera LeConte populations were reduced the following season by 39, 54, and 72%. No economic infestations occurred in the treated area the year following any application. Postspray migration of beetles was very limited, but adult migration during the peak emergence period the following season contributed to repopulation of the treated area. Migration and fecundity appear to be density-dependent factors which favor increases under low populations. Area suppression does not appear economically feasible, but adult control in individual fields may be an acceptable alternative to soil insecticides applied for larval control. A model was developed for timing treatments against adults; treatments between Aug. 1–15 should result in adequate population suppression to prevent damage the following season. Mid-August population levels of 1.0 beetle/ plant were an acceptable economic threshold for determining the need for control measures

Microorganisms Found in Field Specimens Of Diseased Corn Borer Larvae

Two hundred and eighty-six abnormal, field collected larvae of the European corn borer were examined for the presence of microorganisms which could have caused the abnormality or death. The most common microorganism found was a microsporidian, Perezia pyraustae Paillot. Next most numerous was a group of enterobacteria. Spore forming rods apparently of the genus Bacillus, and fungi belonging to the genera Beauvaria and Metarrhizium were also isolated. An examination of 100 apparently normal pupae revealed that 82 were hosts to Perezia pyraustae and two contained bacteria

Some Characteristics of Bacteria Isolated From Diseased Larvae of the European Corn Borer

A large proportion of the bacteria isolated from diseased corn borer larvae are pleomorphic, with rods, diplococci, filaments and various transition forms occurring in many cultures. Gram reaction is negative, although the coccoid forms show a tendency to retain gram positivity. In morphology and biochemical characteristics, these isolates resemble certain entomogenous bacteria described by earlier workers, but are similar also to a group of bacteria from human sources which have been designated as members of the tribe Mimeae DeBord. Further studies have been initiated to determine the pathogenicity and the proper taxonomic position of these cultures

Population Suppression of Western Corn Rootworm by Adult Control with ULV Malathion

ULV malathion (9.7 oz AI/acre) was applied by air to a 16 square-mile area during August of 1968, 1969, and 1970. Adult Diabrotica virgifera LeConte populations were reduced the following season by 39, 54, and 72%. No economic infestations occurred in the treated area the year following any application. Postspray migration of beetles was very limited, but adult migration during the peak emergence period the following season contributed to repopulation of the treated area. Migration and fecundity appear to be density-dependent factors which favor increases under low populations. Area suppression does not appear economically feasible, but adult control in individual fields may be an acceptable alternative to soil insecticides applied for larval control. A model was developed for timing treatments against adults; treatments between Aug. 1–15 should result in adequate population suppression to prevent damage the following season. Mid-August population levels of 1.0 beetle/ plant were an acceptable economic threshold for determining the need for control measures