Model output predicted that flight of pea leaf weevil adults was significantly earlier in Lethbridge than Saskatoon in 2017. In the figure below, note the red line predicting adults emerging from overwintering then the yellow line predicting overwintered adults taking flight this spring for Lethbridge AB (Fig. 1, Upper) and Saskatoon SK (Fig. 1, Lower).
|Figure 1. Model output predicting development of pea leaf weevil in Lethbridge AB (Upper) and Saskaton SK (Lower) in the spring of 2017.|
|Figure 2. Distribution of pea leaf weevil (Sitona lineatus) based on surveying conducted in 2016 (Olfert et al. 2017).|
Pea leaf weevils emerge in the spring primarily by flying (at temperatures above 17ºC) or they may walk short distances. Pea leaf weevil movement into peas and faba beans is achieved primarily through flight. Adults are slender, greyish-brown measuring approximately 5 mm in length (Fig. 3, Left).
The pea leaf weevil resembles the sweet clover weevil (Sitona cylindricollis) but the former is distinguished by three light-coloured stripes extending length-wise down thorax and sometimes the abdomen. All species of Sitona, including the pea leaf weevil, have a short snout.
|Figure 3. Comparison images and descriptions of four Sitona species adults including pea leaf weevil (Left).|
Adults will feed upon the leaf margins and growing points of legume seedlings (alfalfa, clover, dry beans, faba beans, peas) and produce a characteristic, scalloped (notched) edge. Females lay 1000 to 1500 eggs in the soil either near or on developing pea or faba bean plants from May to June.