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The development rates and fecundity of three important pests of strawberry in the UK were determined over a range of temperatures. Development time of the strawberry tarsonemid mite, Phytonemus pallidus, from egg lay to adult, ranged from a mean of 28.4 days at 12.5ºC to 8.8 days at 25ºC. No nymphs developed to adult at 10ºC. Females lived for up to 45 days and laid a mean of 24.3 and 28.5 eggs at 20ºC and 25ºC respectively. Total development time from egg lay to adult for the strawberry blossom weevil, Anthonomus rubi, ranged from a mean of 95.7 days at 10ºC to 18.2 days at 25ºC. Mean fecundity at 20ºC was 157.6 eggs, and the oviposition period averaged 71.6 days. When nymphs were reared on strawberry, development of the European tarnished plant bug, Lygus rugulipennis, from egg lay to adult, ranged from 83.8 days at 15ºC to 28.8 days at 25ºC. Development times on groundsel were shorter and ranged from 65.6 to 22.2 days at 15ºC and 25ºC. Only two nymphs developed to adults at 10ºC; no eggs hatched at that temperature. Mean fecundity at 20ºC was 75.4 eggs, but ranged from 23 to 179. Under a fluctuating temperature regime of 10ºC for 12 h:20ºC for 12 h, nymphs of L. rugulipennis took 40.3 days to become adult on strawberry, and 33.4 days on groundsel. Simple linear models fitted the developmental rate -constant temperature relationship well for all species, accounting for 95-98% of the total variation in observed developmental rates. Development under fluctuating temperatures illustrated the potential problem of extrapolating linear models beyond the conditions of the experiment.

1 The rosy apple aphid, Dysaphis plantaginea , is the most serious pest of apple in Europe and, although conventionally controlled by insecticides, alternative management measures are being sought. Colonies of D. plantaginea are commonly attended by ants, yet the effects of this relationship have received little attention. 2 An ant exclusion study was conducted in two distant orchards within the U.K. At both sites, ants were excluded from a subset of D. plantaginea infested trees at the beginning of the season and populations were monitored. The number of natural enemies observed on trees was also recorded and, before harvest, the percentage of apples damaged by D. plantaginea calculated. 3 Overall, the exclusion of ants reduced the growth and eventual size of D. plantaginea populations. On trees accessed by ants, greater numbers of natural enemies were recorded, presumably because aphid populations were often greater on such trees. However, this increased natural enemy presence was diluted by the larger aphid populations such that individual aphids on ant-attended trees were subjected to a lower natural enemy pressure compared with those on ant-excluded trees. 4 At harvest, apple trees that had been accessed by ants bore a greater proportion of apples damaged by D. plantaginea . There were also differences in cultivar susceptibility to D. plantaginea damage. 5 The present study highlights the importance of the ant -D. plantaginea relationship and it ia suggested that ant manipulation, whether physically or by semiochemicals that disrupt the relationship, should be considered as a more prominent component in the development of future integrated pest management strategies.

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