Specificity of adaptation to a novel host plant by a seed beetle

Abstract

Adaptation to one novel host plant may simultaneously improve an insect's performance on other unfamiliar hosts, as a kind of cross-adaptation. In selection experiments using an Asian population of the seed beetle Callosobruchus maculatus (Fabricius) (Coleoptera: Chrysomelidae: Bruchinae), larval survival in lentil seeds increased from about 1 to >90% in fewer than 30 generations, and acceptance of lentil by egg-laying females increased two-to three-fold. We examined whether rapid adaptation to lentil altered beetle performance on other grain legumes, including hosts more closely related to lentil than to the ancestral host, mung bean. Three replicate, lentil-adapted lines were compared to the mung-bean (control) line with respect to both host acceptance (oviposition under no-choice conditions) and larval performance (survival to adult emergence, development time, and adult mass at emergence). In most experiments, females from the lentil lines laid more eggs on unfamiliar hosts than did females from the mung-bean line. Greater oviposition on novel hosts could not be explained by variation in potential fecundity, and did not appear to depend on a host's relatedness to lentil. Although survival in lentil remained extremely divergent between the mung-bean and lentil lines (0 vs. >90%), the lines did not differ in larval performance on two other novel hosts (pea and fava bean) that are much more closely related to lentil than to mung bean. Because larval performance is most likely the limiting factor in the potential colonization of a novel host by C. maculatus, our experiments did not provide strong evidence for cross-adaptation. The results suggest that adaptation to even a highly marginal host need not lead to a general expansion of an insect's host range.

Genomic evidence that resource-based trade-offs limit host-range expansion in a seed beetle

“…We established the three reversion lines (L1R–L3R) simultaneously after the lentil lines had spent 62 (L1), 48 (L2), and 45 (L3) generations on lentil (Fig. ), and had reached a plateau with respect to larval performance in lentil seeds (e.g., survival to adult emergence was consistently 90–95% in each line; Messina and Jones , ; Messina and Johnson ).…”

Influence of host use adaptation on the dispersal propensity of Callosobruchus maculatus

“…Cross-adaptation for ovipositional acceptance of novel hosts has also been observed in C. maculatus (Messina & Johnson, 2014; but see Messina & Jones, 2009). In particular, Messina and Johnson (2014) indicated that adaptation in C. maculatus to a lowquality host also led to increased acceptance of other novel hosts.…”

“…Cross-adaptation for ovipositional acceptance of novel hosts has also been observed in C. maculatus (Messina & Johnson, 2014; but see Messina & Jones, 2009). In particular, Messina and Johnson (2014) indicated that adaptation in C. maculatus to a lowquality host also led to increased acceptance of other novel hosts. This type of cross-adaptation suggests the potential for selection to have led to acceptance of a novel host by reducing the overall ovipositional acceptance threshold (Forister et al, 2013;Mercader & Scriber, 2007;Messina & Johnson, 2014).…”

Shaking Youngsters and Shaken Adults: Female Beetles Eavesdrop on Larval Seed Vibrations to Make Egg-Laying Decisions

“…The insect cultures of both strains were maintained in mung bean seeds ( Vigna radiata (L.) R. Wilczek); the same procedures and densities were used in an environmentally controlled room at 12:12 h LD photoperiod at 25°C and 70 ± 10% relative humidity. These two strains were chosen based on their characteristics, which have been previously described [ 28 – 30 , 35 , 37 , 38 , 43 , 44 ]. No specific permits were required for the described studies, which were performed in the laboratory with a cosmopolitan insect pest species.…”